[HN Gopher] Perseverance Rover lands on Mars [video] ___________________________________________________________________ Perseverance Rover lands on Mars [video] Author : malloreon Score : 1487 points Date : 2021-02-18 19:16 UTC (1 days ago) (HTM) web link (www.youtube.com) (TXT) w3m dump (www.youtube.com) | adolph wrote: | Clicking on the solar system icon at the top of this page | provides a JavaScript version of NASA's Eyes solar system mapping | application. You can look up the Perseverance mission as "Mars | 2020" right now. | | https://solarsystem.nasa.gov/interactives/ | MisterBiggs wrote: | NASA works. | perryizgr8 wrote: | I must say that this mission is highly disappointing. No risks, | no major progress, no pushing the limits. | | What does NASA have to show for a decade of work, since Curiosity | landed in 2012? A toy helicopter, a drill that poops pellets. | Billions of dollars and millions of man-hours later, this is the | only progress. | | The truth is NASA has become extremely conservative and slow. | Compare this to the moon landing. NASA went from one man in Earth | orbit in 1961 to people walking on the moon as a matter of | routine in 1969. That is the pace needed for serious | technological progress in space. | | We must let NASA die, and let others pursue these feats, people | who have a real passion for space exploration. If NASA had only a | bit of passion, they would have sent men on this mission, based | on all the learnings from Curiosity. | | Defund NASA. | justforfunhere wrote: | They have put onboard, microphones for the first time, two of | them. We should be able to get some recorded sounds of Martian | surface soon. | | The EDL phase was quite complex this time. The cameras took | pictures of the surface while landing and compared them to the | maps it had from orbital missions. Using these two, it decided in | realtime, which place would be the best of the its landing. This | made it possible for it land in a more difficult terrain, like | the crater where it landed. | [deleted] | davidw wrote: | I love space science and engineering! It's such a beacon of hope | and a demonstration of what we can do when we work hard and | innovate. And it's pretty interesting in its own right. | jaegerpicker wrote: | Yes, especially during the Covid pandemic and the political | unrest in the US. Space exploration has helped keep me sane and | to have some hope for mankind. | ssijak wrote: | It is just mind boggling that something so far away is | autonomously landing on a another planet in such a complicated | manner and reporting back to us. Humans can be amazing, this kind | of achievements always make me tear up from joy. | Shivetya wrote: | Also on https://www.twitch.tv/nasa | | They were showing off a model of the rover, I did not realize | just how large this one is! | [deleted] | sethbannon wrote: | These accomplishments are so damn inspiring. Reminds me of this | West Wing clip: https://www.youtube.com/watch?v=R2HzHSeV9v8 | crubier wrote: | Space exploration is unlike anything else. Perfect combination of | exploring unknowns + badass robots + science. | tectonic wrote: | You can also watch an EDL visualization in your browser: | https://eyes.nasa.gov/apps/mars2020/#/home | | And read about how it will use Terrain Relative Navigation to | find a safe landing spot: https://www.jpl.nasa.gov/news/a-neil- | armstrong-for-mars-land... | | Perseverance is phenomenally complex, its Sample Caching System | alone contains 3,000+ parts and two robotic arms. So exited for | all the sciencing this nuclear-powered, sample-drilling, laser- | zapping behemoth can do when it joins its friends on the only | planet (known) to be inhabited solely by robots. | | Edit: Percy is about to release its two 77 kg Cruise Mass Balance | Devices (is this what NASA calls 'weights'?) to setup the right | lift-to-drag ratio for entry. Mars InSight will be listening for | the 14,000 km/hr impacts of these weights, providing useful | calibration data. We wrote about this in this week's issue of our | space-related newsletter, Orbital Index - | https://orbitalindex.com/archive/2021-02-17-Issue-104/ | michaelwilson wrote: | It turns out that they took 640lbs (!) of weight to mars to be | tossed off at various points during EDL. The video is worth | watching if you'd like some more of the nitty-gritty behind the | process: https://www.youtube.com/watch?v=W0NakShgbHY | rsj_hn wrote: | Thanks for introducing me to the French Space Guy! I am | hooked. | jessriedel wrote: | Great video! I am also surprised by the fact that they bring | that much mass just to jettison. In theory they could mounted | some of the useful mass on a slider/rail system to achieve | the necessary adjustment to the mass distribution without | dropping mass overall, but apparently it wasn't worth the | complexity/volume cost. | | I'm sort of surprised we don't yet have ML powered "de- | accent-ization". His french accent isn't hard to understand | at normal speed, but when I set it to 1.5x or 2x speed it | becomes hard to decipher in a way native speakers usually are | not. If there was just a button (for him or me) to hit to | tweak the sounds a bit to reduce the accent, I bet this | problem would go away. | nippoo wrote: | No need to have a fancy all-new ML algorithm - stick a | text-to-speech output on the auto-generated video subtitles | and you can set it to whatever language you like. | | If the speech recognition / subtitling algorithm can't | understand the nuances of the language, that's going to be | a problem anyway... accented pronunciation is so | multidimensional, you're pretty much going to have to | transcribe syllables/phonemes first... | stargazer-3 wrote: | I, for one, would be uncomfortable with AI removing my | accent. I understand it's for other people to understand me | better - and I am fine with AI-generated subtitles - but | altering the way I speak would reduce the amount of "me" in | ways I'm not fully ok with. | omni wrote: | What's special about speech that makes this argument | apply to speech alteration but not to subtitles? It's a | tool to make you easier to understand, not to erase your | person. | throwaway316943 wrote: | Interesting, are you uncomfortable with the current | option to increase or decrease playback speed? | jessriedel wrote: | You wouldn't need to use it on videos you produce if you | don't want. | _-___________-_ wrote: | I'm amazed that people still say things like "de-accent" as | if there was such a thing as "no accent". You are asking | for a button that makes his French accent more like your | own. It's a separate thing from native vs. non-native | speakers - there are plenty of native English speakers with | accents that you would also find challenging. | aardshark wrote: | There is no such thing as "no accent". There is such a | thing as a more neutral accent, or an accent more widely | understood. | jessriedel wrote: | You are reading something into my comment that wasn't | there in order to pick a boring fight. There is of course | no such thing as no accent a priori, but there is such a | thing as "accents understood by (vastly) more people" and | "accents closer to the mean accent of native speakers". | When I learn Russian, my English accent is not on the | same footing as a Muscovite's; the intended notion of | "de-accenting" the English accent on my Russian is | obvious. | | Consider responding to the substance of the comment | instead. | [deleted] | enriquto wrote: | > accents closer to the mean accent of native speakers | | Notice that, for the case of English, most speakers are | not native, by a huge margin! Native English speakers are | a biased minority, and with a lot of variation within. | Not sure that an "average native" accent is a useful | concept at all. I, for one, tend to find most non-native | English speakers vastly easier to understand than many | native speakers. | jychang wrote: | This is a dumb fight to pick. Dude just wants some ML | software to figure out how to change accents. | | Maybe he wants to change the accent to a Texas accent, or | the Queen's english, who cares, it's the ML part that's | interesting. | jessriedel wrote: | > Notice that, for the case of English, most speakers are | not native, by a huge margin! | | I'm well aware, and this does not rebut any of my points. | | > I, for one, tend to find most non-native English | speakers vastly easier to understand than many native | speakers. | | That "many" native speakers in a language of hundreds of | millions of speakers are hard to understand does not | challenge the claim that a non-native accent brought | closer to any native accent, much less the mean native | accent, will for the large majority if listeners be | easier rather than harder to understand. | lopis wrote: | Note: that's 290kg in NASA units | thamer wrote: | I was hoping someone would link this video, it describes the | various phases with a ton of details that. | | Some of the other videos on this channel are just as in- | depth: the ones about the plumes/exhaust of rocket engines as | well as star occlusions are incredibly detailed. | twic wrote: | > Cruise Mass Balance Devices | | They put those in to make the probe seem higher-quality. They | got the idea from Beats headphones. | azernik wrote: | We were doing that at Meraki back in the early 2010s (it | turned out they were also useful as a heat sink and, because | the metal was exposed to air, a radiator). Pretty sure Meraki | got the idea from some Apple product or other. | darkwater wrote: | Speaking of Meraki, I had an awful experience with those | devices. Basically we were in building with TONS of other | wifi networks around and Meraki network just went crazy | from time to time until we fine tune it down to the channel | for each AP. I mean, for something you pay $$$ to buy the | devices and $$$ each month for the subscription is a pretty | poor experience. | jamiek88 wrote: | Just to set the record a bit straighter and ruin your joke, | those pics of beats with weights were knockoff beats from the | flea market not real. | lathiat wrote: | Reporting on that: https://gizmodo.com/are-beats- | headphones-really-designed-to-... | dmix wrote: | > And read about how it will use Terrain Relative Navigation to | find a safe landing spot: | | So basically TERCOM from cruise missles but used on space | crafts? All you need is a radar countour map of the area and it | can automate it's way to the endzone. | | https://en.wikipedia.org/wiki/TERCOM | FredFS456 wrote: | Perseverance's Terrain Relative Navigation uses a camera | system and generates a full 3D position fix, but the idea is | similar. | spaetzleesser wrote: | They should make km the default unit and not miles.... | mulmen wrote: | Ever been on an airplane? Altitude was almost certainly | measured in kilofeet. | | As noted in other comments, NASA (like the rest of the United | States [1]) does use the metric system. | | But it doesn't matter. Nothing about the metric system makes | it uniquely suitable to landing on Mars. Or space travel in | general. What matters is a consistent standard. | | Internally NASA could use Armstrongs. Where 1 is the weight | or height of Neil Armstrong at KSC on July 16, 1969 at | 13:32:00 UTC. It doesn't matter. As long as it is consistent. | | [1]: https://en.m.wikipedia.org/wiki/Metrication_in_the_Unite | d_St... | dieortin wrote: | It does matter. See the errors caused in the past by using | the imperial system. The metric system has a number of | advantages. | mulmen wrote: | The errors were not caused by the imperial system. The | errors were caused by using the imperial system _and_ the | metric system. Specifically in expecting one system and | getting the other. | zajio1am wrote: | >The errors were caused by using the imperial system and | the metric system | | Using one universally accepted system is core idea behind | metric system. Now, it looks like it is competition | between two equal systems, but historically it is | competition between ideas 'we should have one universal | system' and 'every country/area can stay on their local | systems'. Just all other legacy local systems (outside | u.s. customary) disappeared. | bernulli wrote: | The thing is, though, that you have these conversions | even within the imperial system (https://en.m.wikipedia.o | rg/wiki/Imperial_units#/media/File%3...) but not within | the metric system. | | My experience with U.S. students is that they are having | a much harder time making sense of the imperial system | (that they are used to) than doing problems in metric, | even though they don't use it in everyday life. | mulmen wrote: | Ok, so? | | First off, you linked to a list of english measures which | are not used in the US. Nobody uses fathoms or | barleycorns. | | Here is the list of actual US customary units: https://en | .m.wikipedia.org/wiki/United_States_customary_unit... | | Second, none of that is relevant to landing on Mars. | | The only problem space where metric has an advantage is | in converting between meters, kilometers and millimeters. | | That's great, and it's easy to learn. But it doesn't | suddenly make all problems of distance easier to solve. | | If I am traveling toward Mars at 47 meters per second it | doesn't help me to know that is also .047km per second. | And converting to kilometers per hour involves using base | 60 twice anyway because metric time is unwieldy. | | In reality none of your _measurements_ are going to be | nice round numbers. Mentally converting from meters to km | might be nice sometimes but it's essentially a party | trick. | | It won't help the lander make decisions. The hardware | doesn't inherently work in base 10. | | Does NASA mix meters and kilometers? Isn't that the same | problem that destroyed the Mars Climate Orbiter? | | The fact is the units are irrelevant beyond just being | defined and used consistently. | | Also, I can't think of a situation where I need to | convert miles to feet. My bike ride is six miles, I'm | never going to express that in feet. If I need to | describe the size of a thing in a room I will probably | use feet, maybe inches if it is small. Probably not feet | and inches. I wouldn't use miles at all. Easy conversion | between those units just isn't a problem that comes up. | It's more important to me to have reasonably sized units | and that the person I am communicating with understands | them. | bernulli wrote: | Yes I understand. Imperial is awesome because you can | divide a foot by exactly 2, 3, 4 , and 6, which of | course, is the main problem everyone has every day. | Metric on the other hand sucks because none of my | measurements will ever be nice round numbers. | | The hardware doesn't think in base 10, but having more | than that in imperial makes it better? | | Your document lists 12 mass units alone. I rest my case, | what could possibly be more logical, convenient, and need | less conversion. | | If communication was your major goal, then the system | that is used by 7.3 billion people on this planet would | be your choice. | mulmen wrote: | > Yes I understand. Imperial is awesome because you can | divide a foot by exactly 2, 3, 4 , and 6, which of | course, is the main problem everyone has every day. | | Great, we agree. | | > Metric on the other hand sucks because none of my | measurements will ever be nice round numbers. | | Depends on the situation. Metric units can be useful. | | > The hardware doesn't think in base 10, but having more | than that in imperial makes it better? | | No, it means neither system has an advantage so just pick | one. Or invent a new one that allows better hardware | utilization. | | > Your document lists 12 mass units alone. I rest my | case, what could possibly be more logical, convenient, | and need less conversion. | | I don't convert, I just pick the unit that fits the | problem. | | > If communication was your major goal, then the system | that is used by 7.3 billion people on this planet would | be your choice. | | Yeah I use the metric system all the time. Just like | NASA. | bernulli wrote: | >> The hardware doesn't think in base 10, but having more | than that in imperial makes it better? >No, it means | neither system has an advantage so just pick one. Or | invent a new one that allows better hardware utilization. | | But one of the systems does have an advantage because it | stays in base 10, whereas the other doesn't. | | >> Your document lists 12 mass units alone. I rest my | case, what could possibly be more logical, convenient, | and need less conversion. >I don't convert, I just pick | the unit that fits the problem | | But you can't if you just use the `intuitive unit', and | that's the whole problem. How would you measure the | amount of liquid fuel in, say, the small tank for an | attitude control thruster of some probe? How does that | add to the overall mass of the whole probe? Or to the | force you then need to accelerate it by a certain amount? | And now compared to the whole launcher? | | In which units do you measure everything going on in a | small wind tunnel model, and how do you compare that with | the real thing? | | Under which conditions do you go from fluid ounces to | ounces to cups to pints to quarts to gallons (also note | that, again, you not only switch units but bases)? | | >Yeah I use the metric system all the time. Just like | NASA. | | Good for you, it solves all the problems. | mulmen wrote: | > But one of the systems does have an advantage because | it stays in base 10, whereas the other doesn't. | | That's a benefit to humans, not to hardware, which was | the context in which I was speaking. | | > But you can't if you just use the `intuitive unit', and | that's the whole problem. How would you measure the | amount of liquid fuel in, say, the small tank for an | attitude control thruster of some probe? How does that | add to the overall mass of the whole probe? Or to the | force you then need to accelerate it by a certain amount? | And now compared to the whole launcher? | | Honestly? I'd probably _measure_ it in volts. That 's | what the hardware is doing after all. That's my point, it | doesn't help the computer to convert to base 10 and do | calculations that way. Fuel level is measured in volts | using binary. For a human something like grams probably | makes more sense so sure, display it in those units. But | that's a conversion. | | > In which units do you measure everything going on in a | small wind tunnel model, and how do you compare that with | the real thing? | | Again, volts on strain sensors. Maybe analog or maybe | binary, in newtons. Again, the hardware doesn't think in | units humans prefer. There has to be a conversion that | doesn't use simple in-your-head math. | | > Under which conditions do you go from fluid ounces to | ounces to cups to pints to quarts to gallons (also note | that, again, you not only switch units but bases)? | | Cups, pints, quarts and gallons are all based on the | ounce and powers of two. A gallon is 128oz, a half gallon | is 64oz, a quart is 1/2 of a half gallon (or a quarter | gallon) or 32oz (also, approximately a liter). A pint is | half a quart or 1/8th of a gallon or 16oz, a cup is half | a pint or 1/16th of a gallon or 8 oz. These fractional | scales are really handy for converting between units in | some situations. The unit fits the task at hand or you | can trivially double or halve the size of the unit if | needed. It's the same fractional scale and math used with | the inch. | jerven wrote: | I just want to add. It's quite common in carpentry to | work with 120cm base wood. Which devides just as nice. | And even then it's easier to convert when moving into | bigger or smaller units. | cambalache wrote: | Without looking could you tell me.. | | How many pounds does a cubic feet of water have? | | How many BTUs do you need to heat 10x10x3 ft water pool | 20 degrees F? | | How much work in ft-lb is done by gravity when a 10 oz | mass drops from 19 yards? | | How many HP are needed to rais 2400 lbs 74 inches in 30 | sec? | | It is obvious you have 0 experience doing back-of-the- | envelope calculations for scientific or engineering | purposes. It is a no-contest between the metric and the | imperial systems. | mulmen wrote: | I'd love to have a box of JPL envelopes so I can do | calculations like a real engineer. | lmm wrote: | > If I am traveling toward Mars at 47 meters per second | it doesn't help me to know that is also .047km per | second. | | Yes it does. It means you can immediately sanity-check | your numbers even if you don't have a good sense of what | meters and kilometers are, because you have that | base/kilo relationship. | | > My bike ride is six miles, I'm never going to express | that in feet. | | You can eyeball how fast you're going in feet per second | and have a rough idea of how long your ride is going to | take. Or rather you could if you had any idea of how long | your ride was in feet. There are lots of little everyday | things that just become much easier. | mulmen wrote: | I'm not sure how that sanity check works, can you | explain? Do you mean checking conversion between meters | and kilometers? Because sure, that's easier but you could | just do everything in meters instead and not run the risk | of crashing a spacecraft because of unnecessary | conversions or bad assumptions. | | I estimate my bike ride progress in landmarks and time. | Not feet per second. Did I get to the boat ramp in | 20minutes? Better speed up and get to the park by 30. | lmm wrote: | > Do you mean checking conversion between meters and | kilometers? Because sure, that's easier but you could | just do everything in meters instead and not run the risk | of crashing a spacecraft because of unnecessary | conversions or bad assumptions. | | But you'll have small distances and large distances and | pieces from external sources who use measurements on a | scale that makes sense to them. You can make your | external sources do conversions themselves, but that's | just moving the problem around. There will usually end up | being a point, or probably several points, where you have | to relate a small distance to a large distance, and | wherever that happens, a human sanity check is a help. | | > I estimate my bike ride progress in landmarks and time. | Not feet per second. Did I get to the boat ramp in | 20minutes? Better speed up and get to the park by 30. | | Precisely - you have no sense of the relation between | your speed and how far you can go, because you're using a | terrible measurement system, and you don't even notice | the how that's robbing you of the ability to develop | useful intuitions. | mulmen wrote: | My bicycle doesn't even have a speedometer so I'm not | sure how the metric system is supposed to expand my | world. I'm happy looking around and glancing at my watch. | | Miles per hour is literally a measure of distance over | time. If I wanted to use my GPS I could very easily | determine how far I can go in a given amount of time. I | can do this equally well in the metric or imperial | systems, without converting to feet or meters. | Cthulhu_ wrote: | Quick, how many miles is 26357 feet? | | With metric it's a matter of shifting the decimal. | | How much is a sixteenth inch anyways. | mulmen wrote: | Yes, conversion between mm, cm, m and km is easy. What's | your point? If something is miles away why do I care | about it in terms of feet? How many meters is the sun | from here? How many km is 1/3 of an AU? How many seconds | does it take light to go a meter in vacuum? | | A 16th is half an 8th. Twice as much as a 32nd. AKA 2^4, | 2^3 and 2^5, respectively. | Melkman wrote: | Consistency is not the only value of a system of units. | Convenience is also of importance. And that is where the | metric system shines. Having all measures of a unit in | multiples 10 combines perfectly with our decimal | calculations. Having as few as possible magical numbers to | convert and combine between units makes making mistakes | harder. How many calories in kinetic energy has a pound | going 10 miles per hour ? I know a kilo going 10 meters per | second has 50 joules of kinetic energy without looking up | anything and doing the calculation in my head. | killjoywashere wrote: | Can't talk to the statute mile, but the nautical mile is | sublime: one minute of latitude. The amount of math you | can do in your head with a system with so many factors of | 2, 3, and 5 is truly amazing. | mulmen wrote: | I'm not aware of any tricks to make mile calculations | easier but the fractional scale common with the inch is | very useful for real-world mental calculation and | practical exchange. Effectively everything is powers of | two. Got something between 1/4 and 1/2 inch? Great, use | 1/8ths. It's three. Not close enough? How about five | 16ths? It infinitely scales to provide another unit that | is suited to the measurement at hand. In some contexts | you might just say you pick the closest 1/8th. In others | you might use 32nds. You can use the same measuring | devices to agree on an ad-hoc standard that everyone | understands. | | But with the metric system you only really get cm (too | coarse) and mm (too fine) but you don't get something | like 9/16 so you can't "work in 16ths" and have | everything be whole units again. | | Adjusting HVAC in degrees-C is infuriating to my | Fahrenheit sensibilities. 20C is cold, 22C is hot. 21C is | probably ok but really I want something like 20.5C. The | comfortable range for a room is 3-5 whole units of F, but | requires a bunch of fractions in C that you may not even | have available on your thermostat. | | Sure, converting between units is easy in the metric | system. That doesn't make it the best thing to use all | the time. Hell, the idea of thousandths of an inch is | used commonly, so even the imperial system is base 1000 | in some cases. But I've never seen anyone utilize the | fractional scale with metric units, probably because the | units are the wrong size for that to be useful. | onion2k wrote: | _But with the metric system you only really get cm (too | coarse) and mm (too fine) but you don 't get something | like 9/16 so you can't "work in 16ths" and have | everything be whole units again._ | | People who use metric units are perfectly happy rounding | to the nearest 0.5cm or 0.25cm if that's what's needed, | exactly as people do with inches. Why on earth would you | imagine people use mm if something doesn't call for them? | mulmen wrote: | But does anyone say 1/8th centimeter? Seems easier to | just drop down to millimeters at that point. Which is | fine, but it loses out on the convenience of fractions. | onion2k wrote: | People do say things like 1.25mm, which is 1/8th of 1 cm. | | Presumably someone who uses Imperial would say 5/128th | inches if they wanted to describe something that's | equivalent to 1mm? | Evidlo wrote: | Most likely they would use mils/thou. | | 25mils ~ 1mm | | Or 1/16in as others have said. | danaliv wrote: | Also the average of one minute of arc on a great circle | route, which was the real handy thing about it at sea. | killjoywashere wrote: | Yes, meridians (on which latitude is measured) being a | special case of great circle routes that happen to pass | through the poles. That said, as a practical matter, you | are more frequently contemplating a chart of smaller | scale than "globe" so you're usually counting up distance | between fixes, or distance to next turn in a harbor, or | some such thing, where you have a compass in hand and | just need to set the compass to the length of a mile. The | nearest latitude tick marks are quite handy for that. | sojournerc wrote: | As an occasional woodworker and carpenter, I can tell you | having evenly divisable (inch) measurements makes mental | division a whole lot easier. It's just a case of using | the right tool for the job. | mulmen wrote: | It's unfortunate that fractional measurements and the | base size of units get conflated. | | Maybe metric users do use fractions and I just don't hear | about it. Is that table one and a quarter meters high? | spaetzleesser wrote: | People often say something is 1 and a half meters long. I | don't understand how people can work with inch | measurements. How do you divide 7"3/8 by 5? This seems a | major pain. | chordalkeyboard wrote: | You multiply 7* 8 then add 3 and put that number over 8* | 5, resulting in 59/40, roughly 1.5". | mulmen wrote: | One and a half seems natural. What about something like a | quarter meter? I guess that just becomes some number of | centimeters? | | > How do you divide 7"3/8 by 5? | | Same way I divide 4.7625 cm by 5. With a calculator. | flemhans wrote: | > I guess that just becomes some number of centimeters? | | 25, yes. It's not too hard to do the math. | | > Same way I divide 4.7625 cm by 5. With a calculator. | | That's roughly 0.95 right by intuition, but (7"3/8) / 5 | doesn't come easy to me. | sojournerc wrote: | There's something just right about 1/16th of an inch. | About the same as a millimeter, and easy to do math | with... it is weird though 1/8th, centimeter is hard to | conceive, for me anyway. | | When more precision is needed, so easy to go to the 32nd | ascorbic wrote: | All you're saying is that inches are what you're used to. | Being in the UK I am familiar with both inches and mm, | and mm are far easier to work with than 16ths of an inch. | grecy wrote: | We use millimetres. That table is 1250mm high. | | If you're cutting it yourself, a precision of 1mm is | finer than your saw blade or pencil line anyway, so it's | plenty enough. | | When I hear anything past about 1/8th of an inch my brain | shuts down, and I give up. | mulmen wrote: | My argument is a mm is too fine in that situation. 1/8ths | and 1/16ths are ideal when working at those scales. | | In reality I use both systems all the time. It's | situational. | | > When I hear anything past about 1/8th of an inch my | brain shuts down, and I give up. | | Realistically, same. 32nds don't get used outside of some | specialty wrenches. 16ths are a practical limit where | other scales start to make more sense. Probably | millimeters. | cambalache wrote: | So 3 mm is a weird measure but 1/8 of an inch is just | perfect? You are like those guys who say that Fahrenheit | is better because it feels "more natural and obvious" | mulmen wrote: | I don't understand why it has to be one or the other? | Working in fractions is nice sometimes. Inches are a | useful size for some situations. I find it easier to say | that's three eighths than 9mm because my ruler doesn't | have different marks for the factors of each mm mark. | | I use both systems. | | I do prefer Fahrenheit for HVAC (and weather) because | it's higher resolution and has reasonable values at human | scales. Thermostats that lack half-degrees-c are never | quite right IMO. | cambalache wrote: | > I do prefer Fahrenheit for HVAC (and weather) because | it's higher resolution and has reasonable values at human | scales. | | So you are one of those, lol. There is nothing "less | human" about 25 C than say 72 F. Nothing, it just happen | to be the scale you are used to.Both are arbitrary. | | > Fahrenheit for HVAC (and weather) because it's higher | resolution | | 99.99% of thermostats and thermometer in C had at least 1 | decimal place. At usual "human temperatures" the | difference in resolution between the scales is less than | 2X, so even assuming only integer values, I am willing to | bet against you in a double blind test that you cannot | differentiate 68F vs 69F in an statistical significant | way. | | > I find it easier to say that's three eighths than 9mm | | Just because you are used to. Fractions are more | complicated than integers, every elementary school | program knows it. | | So to summarize, the problem is not with the magnitude of | the units which is arbitrary (a degree F and inches are | not more human, logical or normal that a degree C or | cm)the problem is with the convoluted way of the imperial | system for multiples and submultiples of the base unit. | mulmen wrote: | "Human scales" meaning temperatures that won't burn my | skin or give me frostbite. 70 is nice. 60 is cool. 50 is | cold. 40 is really cold. 80 is hot. 90 is really hot. 100 | is potentially dangerously hot. | | I guess 20.5 is nice, 15.5 is cool, 10 is cold, 4.5 is | really cold, 26.5 is hot, 32 is really hot and 37.7 is | dangerously hot. It's fine if you are used to it but I | don't really see a benefit. | | I was in a hotel room in Japan that only had whole unit | adjustments for the A/C. To get 20.5C I had to switch to | Fahrenheit. I guess I was unlucky. | | I find distances in metric and imperial perfectly usable | and use both regularly. | | As outlined in detail elsewhere in the thread there are | advantages to working in fractions in some situations. | Specifically when using a ruler or tape measure with | different markings for 1/2, 1/4, 1/8 and 1/16. There's no | reason that has to be unique to inches, it just works out | well in some cases. | thiht wrote: | > I guess 20.5 is nice, 15.5 is cool, 10 is cold, 4.5 is | really cold, 26.5 is hot, 32 is really hot and 37.7 is | dangerously hot. | | Or, you know, 20, 15, 5, 30 and 40 instead of the | arbitrary decimals you chose to use to prove your point | mulmen wrote: | Sure, you can pick even numbers in either scale that are | awkward decimals in the other. I just prefer the ten | degree bands of the Fahrenheit scale for these ranges. | thiht wrote: | > I just prefer the ten degree bands of the Fahrenheit | scale for these ranges. | | To the identical 5 degrees range of the Celsius scale ? | mulmen wrote: | It's not really identical though. Like I said, Fahrenheit | is higher resolution at these scales so that is an | advantage. It doesn't mean everyone should convert to F. | Just that both systems have benefits. If I changed my | perception of the world to C I wouldn't actually gain | anything, personally, in the context of weather and HVAC. | | If I need to take measurements while boiling water or | making ice then I would probably use C. | [deleted] | mulmen wrote: | If working with simple units of ten is beneficial then | every mission should redefine units in terms of expected | velocities and vehicle size so they are optimized for the | actual calculations at hand. | | That's not realistic, obviously, so we just pick one. The | units in the system are arbitrary, really. | | In reality regardless of the system you choose every | calculation is going to end up with fractions of | something. You aren't just going to do it in your head. | heisenzombie wrote: | Physicists are quite fond of redefining units so that the | constants they care about are all just 1. | (https://en.wikipedia.org/wiki/Natural_units). | | For example, you could define mars units where the | gravitational acceleration on mars is 1. Now your | velocity in freefall is just equal to the time you've | been freefalling! You don't even have to do a | calculation! | | (note: Don't actually do this. Gravitational acceleration | isn't a constant when you're doing orbital mechanics.) | mulmen wrote: | Honestly I would expect something _like_ that to be | happening at a hardware level. The number of bits in a | memory address for the ground sensing radar _is_ very | interesting. Or the algorithm to determine vehicle | acceleration given the voltage reading of a solid-state | sensor vs the baseline. The metric system vs the imperial | system is not an interesting distinction in these | contexts. | boilerupnc wrote: | NASA has experience in unit foul-ups. Mars Climate Orbiter is | the $125M poster project reminding everyone of the importance | in having consistency in units. | | "At 09:00:46 UT Sept. 23, 1999, the orbiter began its Mars | orbit insertion burn as planned. The spacecraft was scheduled | to re-establish contact after passing behind Mars, but, | unfortunately, no signals were received from the spacecraft. | | An investigation indicated that the failure resulted from a | navigational error due to commands from Earth being sent in | English units (in this case, pound-seconds) without being | converted into the metric standard (Newton-seconds). | | The error caused the orbiter to miss its intended orbit (87 | to 93 miles or 140 to 50 kilometers) and to fall into the | Martian atmosphere at approximately 35 miles (57 kilometers) | in altitude and to disintegrate due to atmospheric | stresses."[0] | | [0] https://solarsystem.nasa.gov/missions/mars-climate- | orbiter/i... | lmilcin wrote: | Actually, NASA uses metric system internally. Imperial units | are probably used for general public convenience. | spaetzleesser wrote: | Considering that one of NASA's roles is to inspire young | people to enter STEM I think it would be important to | promote metric as much as possible. | lmilcin wrote: | I don't see how the choice here can promote STEM. | | Do you think kids find it sexy to talk about meters, | kilograms and degrees Celcius rather than feet, miles, | pounds and Fahrenheit? | | I can't fault for choosing what is more understandable to | the target audience. | fckthisguy wrote: | As another commenter said, NASA uses metric. | | During the stream, you can hear the various teams giving | measurements in metric, whilst the media gave coverage in | imperial. | | It's a pretty interesting video from that perspective, as you | can hear the two "realities" being translated for the | intended audience. | tectonic wrote: | Also, InSight's SEIS seismometer is a true marvel: "We have | been able to detect, at about 10 hertz, displacement of the | ground of the order of less than 5 picometers...which is a | fraction of the size of an atom." -- | https://eos.org/features/a-modern-manual-for-marsquake-monit... | peter303 wrote: | LIGO puts this shame with 10^11 better sensitivity. | koheripbal wrote: | Any idea when they will start experimentation? I want to find | microbial life! | Nzen wrote: | I don't know in general, but JPL published a video [0] | yesterday of three interviews. One of the systems engineers | for the MOXIE (atmospheric oxygen separation) unit will wait | several weeks after landing before their first experiment. | Actually, scientific american has published a timeline that | seems to corroborate that [1]. | | [0] https://youtu.be/TUd604rBR6I?t=643 | | [1] https://www.scientificamerican.com/article/the- | first-100-day... | frabbit wrote: | What is it about that that excites you so much? | | Is it the idea that life could originate elsewhere and that | there might really be aliens? | | Or is it the idea that Mars could support some sort of | colony? | | Or the hope of completely novel microbiology? | yellowapple wrote: | Yes. | | Any one of these things would be a massive boon to our | understanding of life throughout the solar system and | broader universe, right down even to here on Earth. All | _three_ of them would arguably mark a new era in Earth 's | history. | cdelsolar wrote: | we are very screwed if they find life on Mars. It means | life is incredibly common and thus the Great Filter | theory is true and we only have a few years left as a | species most likely. | DowsingSpoon wrote: | Disagree. If there is a filter at all then it could | easily be that we've already passed it. Maybe the filter | is the formation of multicellular life, for example. | Also, Earth and Mars have exchanged a lot of material. If | we find Mars life, it would not at all be surprising to | learn it is related to Earth life. | yellowapple wrote: | > and thus the Great Filter theory is true | | Or we're just ahead of the curve. | JohnJamesRambo wrote: | I find it extremely hard to believe you could kill every | human being on earth at this point. We've reached | critical mass, we aren't going anywhere. When we had that | few thousand individuals population bottleneck in the | past was when it was dicey. What sort of event could kill | every human and end our species? I can only think of | planet-wide extinction events like massive asteroid | impacts that sterilized the whole earth. And we haven't | ever had one of those in billions of years. Call me too | optimistic but I think humans are too resourceful. Some | of us would survive anything smaller. | sjy wrote: | There have been at least five mass extinction events in | the last 500 million years. The most recent one wiped out | all non-avian dinosaurs, after they had dominated the | earth for 100 million years. Tool-using apes with | language have been around for less than 5 million. I | think it's far too early to say we'll survive the next | extinction event, or even make it that far before | diverging into new species. | mongol wrote: | I wonder what a huge Carrington solar storm would do to | humanity. If electricity went out everywhere, | transformers burned up all over, electronics fried. If | this caused transport failures, mass starvation could | follow. I really hope a severe solar storm would not be | as bad as that and hopefully someone could enlighten me | on this. | saagarjha wrote: | Killing literally every single human being is not easy. | Sure, killing off half of humanity is pretty easy to | conceive, but to kill all of humanity it takes a lot more | work. | xaqfox wrote: | Luckily, we have great minds working on this problem: | https://www.appliedeschatology.com/ | throwaway0a5e wrote: | >I wonder what a huge Carrington solar storm would do to | humanity | | Worst case it sets us back to 1870ish, maybe. Depends on | how fast things go to crap vs how fast things can be | rebuilt. | | Likely case you'd basically get a "purge" because society | as we know it can't keep on rolling with the kind of | economic breakdown something like that would cause so | there's be a lot of dying in the interim but if you don't | starve or get shot in the first 6mo you're probably good | with the very old, very young and unproductive bearing | the brunt of it (same as every other disaster) It would | be like the black death, but global and all at once. | Balance of power globally would definitely be altered in | unforeseeable ways but the overall net result is things | would bounce back hard. | yellowapple wrote: | > When we had that few thousand individuals population | bottleneck in the past was when it was dicey. | | Yeah, but those individuals were presumably all in pretty | close proximity to one another. If we were left with a | few thousand individuals across the entire range of the | human-inhabited Earth, we'd have one heck of a time | continuing as a species. | | In any case, the risk of an extinction event on Earth is | exactly why I believe space colonization needs to be | Priority Zero for humanity, from two different angles: | | 1. Living beyond Earth means that we as a species are | that much more resilient against a literal-Earth- | shattering catastrophe (and if we can get the bulk of | Earth's current/future population _off_ of Earth, then we | might very well be able to avoid a couple different | plausible extinction events). | | 2. If we can colonize entirely inhospitable worlds like | Mars or the Moon (or my votes, Ceres, Venus, and | Enceladus), then "colonizing" Earth is easy-peasy-lemon- | squeezy even if it does become Venus 2: Greenhouse | Boogaloo. | russtrotter wrote: | Some interesting reasons: the proverbial "2nd genesis", | panspermia possibilities of our own planet, and answering | lots of questions on formation of life on ours and any | other planet we might encounter. | WJW wrote: | > is this what NASA calls 'weights'? | | Well no, the Cruise Mass Balance Devices are intended to | Balance the Mass of the spaceship during Cruise conditions. | That these Devices are single-part and constructed out of a | single chunk of metal each should not be construed as merely | being 'weights'. :) | theelous3 wrote: | What I'm getting from this, is that you can use weights to | balance the mass of the spaceship during cruise conditions. | numpad0 wrote: | Actually more like that you can eject weights to | intentionally un-balance the mass of a spaceship so it'll | glide rather than falling straight down. | | Atmospheric drag force center of drag and center of gravity | to line up on a same axis, which force the craft to fly | slightly sideways if spacecraft isn't perfectly balanced. | Done carefully, it leads to direction of flight being | slightly sideways, which is awkward but basically same as | having lift towards that direction. Add roll control | thrusters into the mix, and you get a really crude glider, | with fixed pitch force, zero yaw control and barely | controllable roll. With JPL-class engineering, such a | spacecraft will be capable of actively correcting landing | location. | jcims wrote: | It's like hypersonic curling | Aeolun wrote: | Maybe they have both, and needed a name to distinguish the | ejectable weights from the non-ejectable weights? | xarope wrote: | Ships do this all the time (ballast), and anybody who's | ever flown on a light aircraft or helicopter also knows the | importance a pilot places on weight distribution. | | I guess what's surprising is that they needed that much | weight (140+kg seems like a lot?) and couldn't redistribute | existing componentry; guess the knapsack algorithm wasn't | good enough, or that they just couldn't break up enough | pieces? | | And yes, Cruise Mass Balance Devices sounds like the type | of name a tired engineer would come up with to convince | upper management...lol | FredFS456 wrote: | They can't redistribute existing componentry because of | competing requirements: during cruise, the spacecraft | needs to be balanced around the rotational axis | (perseverance rotates at 2RPM in cruise). During re- | entry, an asymmetric weight distribution is needed to | generate lift. | xarope wrote: | Surely you mean: "What I'm getting from this, is that you | can use devices to balance the mass of the spaceship during | cruise conditions"...j/k | rkagerer wrote: | Got it. Fancy weights. | [deleted] | nerfhammer wrote: | from the author of that software | https://twitter.com/mrdoob/status/1362508150507790343 | nelsonmandela wrote: | Apparently the copter was made with off-the-shelf parts. | | I wonder if I can cop a replica somewhere, and how it would fly | considering it is built for martian air | kibwen wrote: | Here's a really excellent video that answers all your | questions: https://m.youtube.com/watch?v=GhsZUZmJvaM | | TL;DW: Martian atmosphere is so sparse that it's equivalent to | flying at 100,000 feet on Earth. (The altitude record on Earth | is 85,000 feet, set by the SR-71.) In order to fly at all the | blades have to spin at nearly the (Martian) speed of sound. The | drone wouldn't fly on Earth because the atmosphere is so dense | that the blades would never make it up to speed. | dralley wrote: | > (The altitude record on Earth is 85,000 feet, set by the | SR-71.) | | The A-12 Arkangel flew higher (95,000 feet) and faster, but | was short-lived and so highly classified that it doesn't hold | any "official" records. | | And a MiG pilot flew up to 123,000 feet, but only on a | ballistic trajectory, it wasn't a sustainable altitude. | ggreer wrote: | If it was made with off-the-shelf parts then it's a testament | to how wasteful NASA has become. Building that helicopter took | them 6 years and $80 million.[1] | | 1. See page 20 of the launch press kit: | https://www.jpl.nasa.gov/news/press_kits/mars_2020/download/... | vietjtnguyen wrote: | They can't exactly procure a bunch of parts and then call it | a day. Lots of the cost is tied to the verification and | validation. Then there's the system design, requirements | engineering, trade studies, system integration, engineering | models, simulation, software, environmental testing, launch | costs, ground command and data systems, interfacing with the | rover, etc. Paying engineers to do all that is what makes it | so expensive. | m4rtink wrote: | Yeah, with launch windows every two and hal years only, 9 | months of travel time, still expensive launch costs and | complicated landing requirements you really need to make | sure stuff works. | | Sure, for stuff you can reasonably test in Earth gravity | and atmosphere you can just weld stuff together in a field | and then fly it until it stops crashing. Thats a case when | you can iterate quickly and relatively easily with lots of | COTS stuff. | ggreer wrote: | The $80M doesn't cover the launch costs. That would be part | of the $2.4B for the overall rover project. | | For comparison: SpaceX's entire Falcon 1 program cost $90M | over 6 years. That was to develop two new rocket engines | (Merlin & Kestrel), build out the launch site on Omelek | Island, and launch five times. | vietjtnguyen wrote: | Sure. I meant it more in the sense that there are some | launch costs associated with the Mars Helicopter because | it consumes mass budget. | | As to the SpaceX point. Yes, I think SpaceX is more | efficient with their money than NASA, but this will boil | down to a discussion of counterfactuals and degrees of | "wastefulness". Was NASA wasteful? What does it mean to | be wasteful? What's the threshold? What would it cost | SpaceX to build the Mars Helicopter? Can we really | compare a launch vehicle versus a tech demo of a | rotorcraft operating on another planet? Would that $80M | be better spent just funding SpaceX? I don't know. I just | don't think it's fair to simply say "If it was made with | off-the-shelf parts then it's a testament to how wasteful | NASA has become". The engineering has to happen. Could | NASA have been more efficient with it? Probably. Was it | wasteful? I don't think so. | tectonic wrote: | A super exciting and well-executed landing with years of practice | ahead of time to make it look easy. Things I'm looking forward | to: - Sample collection and caching for pickup by a future sample | return mission | | - Flying an experimental helicopter on Mars | | - Gauging the habitability of its landing region (Jezero Crater, | a paleo-lakebed with preserved river delta and sediments) and | hunting for ancient microbial biosignatures (with lasers!) | | - A drill (that can cut intact rock cores, rather than | pulverizing them like Curiosity) | | - An ISRU experiment that makes oxygen from CO2 | | - Way more advanced autonomous navigation | pklausler wrote: | I very much enjoyed learning a new acronym: SUFR ("straighten up | & fly right", if I remember rightly). | me_me_me wrote: | Helicopters on Mars, what a time to be alive! | rpiguyshy wrote: | im really sad to say that NASAs website is an absolute dumpster | fire... does anyone know of a simple repository of all the images | and videos captured by each mission? i just want to flip through | the pictures perseverance has taken so far without sifting | through cancerous news sites. | | edit: the closest thing ive found is data.nasa.gov. how hard is | it to just generate a fucking simple html website with | chronologically ordered images? this is bullshit | | edit: ok, here is almost exactly what i wanted: | https://mars.nasa.gov/mars2020/multimedia/raw-images/ the | internet really sucks compared to what it might be... go to | nasa.gov and click percy mission from the drop down and it takes | you to a part of nasa.gov thats filled with eye-cancer tiles and | javascript with sensor imaging mixed in with PR images and | promotional material. but they tuck the (sort of) clean, | organized data into some other website basically? maybe its a | small gripe but this way of doing it is disorganized and | infuriating. | | edit: wow, this website is fucking amazing! you can see the real- | time position of all nasa mars vehicles 3D google earth style: | https://mars.nasa.gov/explore/mars-now/ anyone who has not looked | around in mars.nasa.gov should bookmark that right away | | curiosity shots: | | https://mars.nasa.gov/raw_images/895098/?site=msl | | https://mars.nasa.gov/raw_images/896437/?site=msl | | https://mars.nasa.gov/raw_images/895971/?site=msl | | https://mars.nasa.gov/raw_images/895971/?site=msl | | https://mars.nasa.gov/raw_images/895077/?site=msl | | https://mars.nasa.gov/raw_images/891625/?site=msl | | https://mars.nasa.gov/raw_images/888957/?site=msl | | https://mars.nasa.gov/raw_images/887028/?site=msl | | https://mars.nasa.gov/raw_images/886343/?site=msl | drewblaisdell wrote: | When can we expect any imagery from Perseverance? The Curiosity | photos were incredible. | ryankrage77 wrote: | Probably around 20-30 minutes after it's landed. Perseverance | needs to lock onto sattelites that are part of the Deep Space | Network for the bandwidth required to send media. It also takes | 22 minutes to send a command and get a response back. | ceejayoz wrote: | It was already communicating with DSN the whole way down, via | one of the orbiters, and "send a pic" was apparently a pre- | programmed command not requiring Earth initiation. | comfydragon wrote: | We actually got a picture like 3 minutes after landing. | (Okay, a picture from shortly after landing.) | someperson wrote: | Probably routed through the Mars Reconnaissance Orbiter, | Maven and possibly Europe's Mars Express satellites, rather | than a direct connection to the Deep Space Network | | https://en.wikipedia.org/wiki/Mars_Reconnaissance_Orbiter | | https://en.wikipedia.org/wiki/MAVEN | shadowgovt wrote: | If I understood the livestream correctly, it's because they | were able to (maintain|quickly establish) lock to the MRO | after touch-down and zip a couple of images up through the | "bent-pipe" UHF-to-high-power relay into the Deep Space | Network. | GeorgeTirebiter wrote: | It would seem they had MRO in position to snap a few | photos of the landing / descent as well as do the relay. | jasonjayr wrote: | First few low-res pictures posted here: | | https://twitter.com/NASAPersevere | | I'd bet they post the first high-res pictures once they arrive. | The link from Mars to earth is sending a lot of information | about what just happened, so understandably bandwidth is pretty | saturated | f154hfds wrote: | Pictures already coming in to JPL apparently. | | https://www.youtube.com/watch?v=kPrbJ63qUc4 | ilrwbwrkhv wrote: | It brings tears to my eyes. When the touchdown happens, these | people experience a level of joy and satisfaction which I can | only dream of while doing my job of optimizing ad clicks and | profile photos. | thisistheend123 wrote: | This is so awesome. Go Nasa! | | I am amazed at what humans have been able to achieve in short | time since the Industrial revolution. | | After all the negativity of last few months, this brings so much | hope. | | Waiting for the first human foot touch down on Mars in my | lifetime. | koheripbal wrote: | The pandemic has, in many ways, accelerated advancement and | technological development. | burrows wrote: | All hail the shining twin gods, Advancement and Progress. | wiz21c wrote: | I'm a bit surprised that NASA doesn't communicate anymore since | they landed the rover. I thought other pictures would come today | in the morning... | sixothree wrote: | Shout out to the team member with the "This is fine" plush dog on | their desk. | arnaudsm wrote: | Picture : | https://twitter.com/PlanetDr/status/1362487492662996996 | Aperocky wrote: | The dog is a fine addition to any meeting. | thisistheend123 wrote: | How much more time for EDL? Can't find that information anywhere! | [deleted] | devb wrote: | I was wrong... estimated touchdown is 15:55 eastern time. | whitehouse3 wrote: | It's great to see NASA livestreaming in similar quality/fashion | to spacex. It reminds me of watching the NASA feeds on public | television in the 90's but much more nicely produced. | criddell wrote: | On space shuttle launch days, my parents would let me stay home | from school to watch TV. At the time I was an ungrateful idiot | but now I realize my parents understood me better than I | understood them. | hikerclimber wrote: | hope it crashes. | hedgehog wrote: | I read that the design life of the helicopter is five flights. | Does anyone know what the limiting factors are? The brutal cold | and abrasive dust both seem like they could contribute but I am | curious what the real answer is. | bluescrn wrote: | Dust on the solar panel seems likely to be a problem after the | first landing, unless it's got a clever way to keep it clean. | | And its got to be tough conditions for the battery, low | temperatures and probably deep discharges to make the most of | it. | joeyh wrote: | It's powered by plutonium. | | Rovers with solar panels deal with the dust by waiting for a | storm to blow it away. | bluescrn wrote: | Perseverance is powered by an RTG, but the Ingenuity, the | helicopter, is powered by lithium-ion batteries recharged | via a solar panel. | | I'd expect it to kick up a fair bit of dust on landing. But | I suppose that's something else that'll behave a bit | differently on Mars to what we'd expect in Earth's | atmosphere. | sephamorr wrote: | The helicopter doesn't have enough power generation to stay | warm through the Martian winter; the solar panel that feeds it | is extremely small, so at the very least, it is unlikely to | last beyond the summer. Here's the thermal design paper for the | helicopter: | | https://ttu-ir.tdl.org/bitstream/handle/2346/74036/ICES_2018... | dmurray wrote: | The "design life" figure is something like the 5th percentile, | if previous rovers are anything to go by. As in, they can | estimate a 95% chance it makes it through 5 flights. | | I'd bet on it making 20+ at evens. | m4rtink wrote: | If we go by MER Opportunity standards (surviving 55x times | its design timespan) we might go up to 275 flights! :D | happy-go-lucky wrote: | An exceptional feat of the human intellect. Bravo! | jb1991 wrote: | I can't find any articles that highlight what that component that | "flies away" after the landing is going to do next. Does it just | get dumped somewhere? Does it go back into orbit? | solipsism wrote: | It flies either forward (with respect to the rover) or backward | -- whichever is closer to North -- and crash lands on the | surface some distance away. | Plutoberth wrote: | It GTFO with its remaining fuel and then crash lands. Going | back to orbit would require enormous amounts of fuel. | ncmncm wrote: | It's funny that they never say. (My mother-in-law asked if it | would go back to orbit, too.) Saying "it flies far enough | away to be sure it won't hit the lander when it crashes" | would sound funny. They never seem to drive over to check it | out, either, AFAIK. | | It started with ~800 lbs of hydrazine fuel on board that had | to slow tons moving at 200 mph to a dead stop, and then hover | for 10+ seconds while the lander spun down; and then boost | away and crash. ("Crash-land" sounds like entirely more | control than what really happened.) | [deleted] | ckosidows wrote: | I can't find this information online... There were four cameras | capturing video of the descent. Do we know when that footage will | be available? Days? Weeks? Months? | soheil wrote: | So where are the images? (not the black and white fisheye) | FredFS456 wrote: | It will be a while before they get better images downlinked. | The radio link is unbelievably slow by modern internet | standards[0]. Note that the faster 2 Mbps link is only | available when one of the orbiters is overhead (4-6 | times/martian day[1]). They also have a lot of work to do | checking out the rover systems making sure everything is | healthy, etc. | | [0] | https://mars.nasa.gov/mars2020/spacecraft/rover/communicatio... | | [1] https://mars.nasa.gov/mars2020/mission/communications/ | garden_hermit wrote: | Watching these is always a stressful experience, I can't imagine | what it would be like sitting in that room, praying that the | object you spend years of work on is able to land by itself 7 | light-minutes away. | | I'm looking forward to what Perseverance will teach us. | sneak wrote: | > _Watching these is always a stressful experience, I can 't | imagine what it would be like sitting in that room_ | | Sitting in any closed space like that one, with other people, | masks or no, is stressful right now. It's a shame that NASA can | communicate with a rover 125 million KM away but their staff | have to all be crammed into one small enclosed space. You'd | think we'd be able to communicate just as effectively over | several kilometers. | | I imagine that people will look back on videos from this time | period where ~3M people died (mostly unnecessarily) and wonder | what on Earth people were thinking, carrying on like that. | tester756 wrote: | what if those people were tested for covid and there was no | risk? | DonHopkins wrote: | That's how Trump got it, then spread it. | jussij wrote: | This morning on the radio and Australian scientist told the | listeners he had spent 10 years working on his small part of | the Perseverance mission. | | That would help to make the landing quite a nerve racking | event. | spullara wrote: | Right now it is 11 minutes away! | garden_hermit wrote: | I was still under the assumption of Curiosity's 7 minutes! | Thanks for letting me know | SubiculumCode wrote: | You know, in some ways its like any scientific endeavor. | Hypothesis, funding, data collection can take years of effort. | Then you look at your data and test hypotheses, and you have no | control of the outcome. It can be terrifying, to be honest, | which is why I support publishing of negative results. Of | course crashing on Mars would be a terrible null result ;) | ghoshbishakh wrote: | Thank you for posting this. Let's witness what science and | engineering is capable of achieve today. | | It is just amazing to think that a robot is roaming around in | Mars, and a second one might be joining today. | JebusAustralia wrote: | Please donate ethereum to this address as I am being kept hostage | by a psychopath called Satoshi Nakamoto. He has scattered all of | my personal information and economical research all over youtube, | cnbc, techcrunch, the local mainstream media in the netherlands. | https://ibb.co/74qYknK | aaron695 wrote: | I don't get why they had to bring the children into this asking | questions constantly. Do we really want to reinforce this is just | for children? | | SpaceX doesn't do this. They are always top quality. Adults doing | professional things in space, that to me is more inspiring to | children and young adults. | | Can't they have an adult stream and one dumbed down for the | children if they really think these things should be dumbed down. | | It was better than ESA I guess | science4sail wrote: | I wonder if it's a case of misaimed audience? | | Even though "children asking questions" may be less appealing | to children than "adults asking questions", the former might | get aired anyway because it's more appealing to the adults that | make children's programs. | abalaji wrote: | I'm excited for the HD video of the landing that was promised. | Nekhrimah wrote: | And audio as well! | aembleton wrote: | How are they getting audio without an atmosphere? | gillytech wrote: | There is a thin atmosphere on Mars and sound does exist. | It's also how this lander was able to land. | Ne02ptzero wrote: | NASA actually made a pretty informative page about it[1], | with some simulation of sound on Mars, compared to Earth. | Hopefully we won't need the simulation much longer! | | [1] https://mars.nasa.gov/mars2020/participate/sounds/ | vagrantJin wrote: | Mars does have an atmos. | | Or are you reffering to something else? | tcpekin wrote: | Currently watching it using Streamlink [0] to watch in VLC. This | is so exciting! Wishing them, and the rover, all the best in the | landing! | | [0] https://streamlink.github.io/ | Koshkin wrote: | A hacker on HN? | inspector-g wrote: | Watching the live feed was a blast. When they said they received | the exact landing coordinates I was extremely curious to see it | plotted vs their targeted landing zone, but unfortunately they | haven't shown it yet. However, I could audibly hear an engineer | in the background say "Oof, well, we'll take it!" | | Anyone seen anything about the precise location yet? | dylan604 wrote: | In one of the previous threads about Mars missions, one of the | comments was how we have gotten to the ability of "land it | close enough, and we'll drive the rest of the way". Seems | pretty accurate for this mission. | tectonic wrote: | https://twitter.com/jccwrt/status/1362514739671298051 | | > UNOFFICIAL but it looks like Percy landed right on the edge | of the Mafic Floor Unit, with older (probably sedimentary) | rocks that were buried by it only a short drive away. | raphaelj wrote: | NASA's ability of succeeding at landing things successfully on | the first try on foreign bodies since 1969 is mind-blowing. | | Meanwhile, SpaceX takes half a dozen tries before managing to do | the same on a fully known environment on Earth. | dawnerd wrote: | You had me until you started to bash SpaceX for no reason. NASA | has had plenty of failures and you're framing it as if they | haven't ever. | TulliusCicero wrote: | That snipe was really unnecessary. | | Not to mention weird, considering how successful SpaceX has | been at dominating the commercial launch sector. | Daho0n wrote: | I'm not commenting on the rest of your post but the | "dominating the commercial sector" just so you don't think | I'm badmouthing SpaceX. Just wanted to add that if you sell X | pounds of cargo to the commercial sector but sell the same | capacity to the military for X times 3 then your are not | dominating but are subsidized by the state and in a position | to undercut the commercial competition. It's not just for PR | that SpaceX competitors, both foreign and nationally, are | saying SpaceX is propped up by the state. | TulliusCicero wrote: | Was SpaceX uncompetitive in its bids for the government | launches or something? My understanding is that they were | much cheaper than other bidders, not more expensive. | gfodor wrote: | Consider for a second that blowing up no prototypes or blowing | up lots of prototypes are both well considered methodologies | and what you state is by design and expected. | emilecantin wrote: | Perseverance is one of the largest objects that NASA landed | (along with the Apollo lander), and it's about the size of an | SUV. | | SpaceX is trying to land things the size of buildings. | | Let's just say it's a very different problem. | Daho0n wrote: | . | m4rtink wrote: | Actually, all the Starship flights are fully automated, | possibly except a very nervous person somewhere with the | self-destruct button and binoculars. | | If you though there is someone in Boca Chica flying | Starship remotely with joystick and steady hand, I'm afraid | I need to disappoint you. | Daho0n wrote: | That wasn't the point but this is Reddit level snarky | commenting so I'll be on my way. | PeterisP wrote: | Neither Perseverence or SpaceX landings involve latency for | control commands, they are automated/preprogrammed in the | vehicle and do not rely on real-time commands from the | ground. | Daho0n wrote: | No one have said otherwise. The point still stands that | landing on earth is not in the same universe as landing | on Mars. Comparing is stupid. | jaegerpicker wrote: | SpaceX has a very different set of risk tolerances and | approaches. Nasa is a government funded entity and the | tolerance for failure (rightly or wrongly) is very low | according to every thing I've read. | | SpaceX being private has a much larger cushion for failure. | Elon will keep funding it far longer than congress would Nasa | is my guess. If SpaceX loses some rockets that's the cost of | business, of course once those missions are manned it's a huge | difference but until then I think it's not really comparable. | mempko wrote: | You have it exactly backwards. Risk tolerance is higher for | the government. Fox example, SpaceX would never just send a | rocket to mars just to do science which would bring it zero | profits. It won't take risk funding something where the | science may or may not bear any fruit. | | Also, SpaceX IS mostly funded by NASA anyway as a government | contractor. SpaceX exists because the government wanted to | create a private space market. Strangely thank George Bush | for it. https://www.fool.com/investing/2017/02/05/how- | profitable-is-... | | As you can see, SpaceX was so cash strapped in 2017 it | obviously didn't go to mars in 2018 as they wanted. Also | notice Elon didn't fund that trip (otherwise it would have | happened). There is no way he would risk HIS own money on | that. | m4rtink wrote: | Main reason for Red Dragon not happening was NASA | requesting parachute landing into the ocean instead of the | previously planned propulsive landing on land for Dragon 2. | | This would mean that SpaceX would need to develop and fund | Dragon 2 propulsive landing on their own, with only real | mission fully requiring it being Red Dragon. | | In the end it was much easier to just drop the whole thing, | especially with the much more perspective Starship on the | horizon. | macintux wrote: | I'm sure this will be downvoted to oblivion shortly, but it's | mind-boggling that the company who's turned rocket landings so | routine that it's notable when they fail is being singled out | as a failure. | | (Update: sorry, by "this" I mean the parent comment.) | [deleted] | electriclove wrote: | We really should take the SpaceX approach. There is too much at | stake on a singular multi-billion dollar rover landing on Mars | every now and then. We need more funding so that we can send | these things to Mars much more frequently and get samples back | before my kids have their own kids. | FrojoS wrote: | Rediciolous comparison. | | The size of the objects that SpaceX is landing is much larger. | The approach that was used here for Perseverance (Skycrane) | would not work for larger ships, like those required for a | human mission. Just like the previous approaches, e.g. | Lithobraking with Spirit and Opportunity, would not have worked | for Perseverance. | | Larger objects are much more difficult to land. Simply put, | while mass will increase by the power of three, surface area, | which is used for aerobraking only scales by the power of two, | relative to size. | | In order to land something large enough to carry and support | humans (10-100t), you need hypersonic retropropulsion. Guess | who was the first to achieve this? SpaceX. And they remain the | only ones. When they light the three engines for the entry burn | the earth atmosphere is very similar to the relevant section of | the future Mars decent. By developing the first stage landing | of Flacon 9, they solved one of the biggest development | challenges for humans landing on Mars and it was not by | accident. NASA was very happy to get that data and helped them | collect it with their chase planes. | m4rtink wrote: | The Mars atmosphere is at a tricky spot where you can't | ignore it like when landing on the Moon (also Mars gravity is | higher than on the Moon) yet it's not thick enough for | survivable landing with parachutes or wings (as envisioned in | the earliest Mars mission plans) only. | | That's why you always see parachutes + something else for | Mars EDL - parachutes + rockets, parachutes + airbags, | parachutes + skycranes. And in Starship case, high speed | glide and speed shedding with propulsive landing at the end. | nitrogen wrote: | _NASA 's ability of succeeding at landing things successfully | on the first try on foreign bodies since 1969 is mind-blowing._ | | https://en.wikipedia.org/wiki/Mars_Climate_Orbiter | | > The spacecraft encountered Mars on a trajectory that brought | it too close to the planet, and it was either destroyed in the | atmosphere or escaped the planet's vicinity and entered an | orbit around the sun. An investigation attributed the failure | to a measurement mismatch between two software systems: metric | units by NASA and non-metric ("English") units by spacecraft | builder Lockheed Martin. | | https://en.wikipedia.org/wiki/Mars_Polar_Lander#Landing_atte... | | > Communication was expected to be reestablished with the | spacecraft at 20:39:00 UTC after having landed. However, no | communication was possible with the spacecraft, and the lander | was declared lost. | m4rtink wrote: | Mars Observer is mad that you forgot to mention it! | https://en.m.wikipedia.org/wiki/Mars_Observer | | Actually it is not mad - becase it exploded into millions of | pieces due to the leaky fuel system... | macintux wrote: | In fairness to the parent comment: those weren't the first | try. | user3939382 wrote: | Yeah, c'mon Elon. It's not rocket science! | joe_91 wrote: | NASA also requires 10-100x more money & time to do so. Both | just have very different ways of working. Both work and there | are pro's and con's to either way! | notum wrote: | I'll just leave Thunderf00t's latest video here: | https://www.youtube.com/watch?v=4TxkE_oYrjU | | Let's not diminish ether's breakthroughs, but financial isn't | one of SpaceX's. | shazmosushi wrote: | That video was incorrect on so many levels that I have made | a rebuttal: https://www.youtube.com/watch?v=36o4UrS9OS4 | raphaelj wrote: | How could you know? SpaceX never landed or sent a craft on a | foreign body. | joe_91 wrote: | Haha, good point - we'll have to come back in 4-5 years | time when SpaceX have touched down on the moon and mars and | check the cost. Considering their low cost & speed at | getting things into orbit these days and the plans they | have for starship I hope that the data will prove me right | in a few years | m4rtink wrote: | While this timeline might be optimistic, this is what | came to my mind when I heard about the current timeline | for Mars sample return - samples returning back to Earth | in _2031_. | | https://en.wikipedia.org/wiki/Mars_sample- | return_mission#NAS... | | Like it's nice to finally have a firmer timeline for | that, but damn, 10 years from now. A SpaceX employee | gathering the sample tubes into his backpack in a couple | years time to be returned on the next milk-run flight | back to Earth is just so much cooler! :) | joe_91 wrote: | Yes, hopefully SpaceX can do it quicker than 10 years! | Considering 15 years ago they started with their first | rocket and how far they've come in that time I have high | hopes. | | I think Elon was hoping for a manned mission to Mars in | 2024 back in 2017 but his latest projection is 2026. He's | certainly optimistic :) | ALittleLight wrote: | SpaceX hasn't been around as long as NASA. Also, remind me, | did NASA develop reusable rockets? | Rebelgecko wrote: | NASA doesn't really build rockets in-house, all of their | reusable rockets were built by contractors under NASA's | supervision. Sometimes NASA collaborated with other | organizations (e.g. DARPA/military funding paid for a lot | of the DC-X reusable rocket) | m4rtink wrote: | Well, nssa worked on Delta Clipper and DC-X. Also Venture | Star. And the integrated powered demonstrator/FastTrack & | pointless injectors that formed the basis of the Merlin | engine IIRC. | thelean12 wrote: | > Also, remind me, did NASA develop reusable rockets? | | I can't tell if this is sarcasm or not but... yes, of | course NASA developed reusable rockets. The space shuttle | missions reused the shuttles and the boosters. | ALittleLight wrote: | The space shuttle was partially reusable. | marcinzm wrote: | The Space Shuttle was reusable (with massive refurbishing | after each flight) but given that'd it cost significantly | more than a non-reusable rocket per pound I think the | point stands. SpaceX managed to make a financially viable | reusable rocket. | Daho0n wrote: | They really didn't. SpaceX is not cheaper than the | shuttle no matter how many times it gets repeated. That | SpaceX fudges the numbers so it is hard to compare | doesn't make it true. In reality SpaceX is more expensive | than not only the shuttle but also their own projections. | | Here's a breakdown: https://youtu.be/4TxkE_oYrjU | tristanb wrote: | you're wrong. That video is a bunch of crud | Daho0n wrote: | And I'm sure you believe that US and foreign competitors | of SpaceX who says the same thing are just spewing PR, | right? It was a random video. The message is not wrong. | Being snippy doesn't change facts. | Nekhrimah wrote: | > Here's a breakdown: https://youtu.be/4TxkE_oYrjU | | I watched the first 90 seconds of this. On the cost of | re-usability of a falcon 9 point, the figures are shown | as from Wikipedia. | | So 1) not a primary source. 2) fails to calculate the | percentage correctly between $62m and $50m as "around | 10%". It's almost 20% on those figures. 3) and most | importantly, those numbers are the cost to the customer, | not SpaceX's internal cost. As they have no current | competition in rocket re-usability, they are able to | recoup the R&D cost for developing this technology. | | I don't think I'll bother watching the rest of the video. | m4rtink wrote: | Yeah, they are certainly not launching so many Starlinks | at the same price they charge to the customers. A very | big benefit having your own partially reusable rocket | (especially as long as no one other has one yet). | thelean12 wrote: | > I think the point stands | | No it doesn't. The person was trying to say SpaceX > | NASA. Many people here are trying to shit on the other | side as if they have a real point. | | They're both doing cool and useful things and they're | both really really good at what they do. | ALittleLight wrote: | I'm not trying to say that SpaceX is better than NASA. I | am responding to the point that NASA has done things that | SpaceX hasn't (e.g. landing on other celestial bodies) by | pointing out that SpaceX has done things NASA hasn't | (e.g. SpaceX rockets land and can be reused). | | I don't think it makes sense to talk about which is | better unless there is some specific metric that can be | measured so a conclusion could be reached. I am | encouraged though that SpaceX has a trajectory that will | allow greater access to space. By bringing the cost of | space travel down, I expect we will get a lot more of it. | NASA (and other governmental space programs) started the | initiative, but I think SpaceX is continuing it | marvelously. | Daho0n wrote: | I'm not saying SpaceX isn't doing good but the price has | gone up per (re)launch, not down as projected, so at the | moment of it were possible to buy a trip to space for a | few tourists it would be cheaper on a shuttle. | erulabs wrote: | They did, you're not wrong at all, but just to add a | little bit of clarity the space shuttle was never as | reusable as was hoped - it wound up costing a huge amount | of time and money to retrofit the shuttle again before | each launch. Reusable and Re-usability are different | things :P | | As far as I know no solid state boosters were ever re- | used (how would that work?) - but then again SpaceX | doesn't re-use solid state boosters either (because they | do not use any)... | | Things can be more complex and nuanced than quippy | internet back and forth suggest. That's not even touching | on the ship-of-theseus problem that is many former NASA | engineers working at SpaceX these days. | Daho0n wrote: | It doesn't really matter much because a look at the | actual numbers shows that SpaceX charge more than the | cost of launching the exact same payload would have cost | using the shuttle. Besides the reusability point is | disingenuous when talking cost since SpaceX's cost have | actually gone up per (re)launch, not down. So yes, it is | more complex than quippy internet back and forth | suggests. | | Here is a video that explains it in decent details if you | are interested, but the TL;DR is that SpaceX is more | expensive than the shuttle and way more expensive than | they said they would be: https://youtu.be/4TxkE_oYrjU | m4rtink wrote: | The SRB segments vere regularly reused, not sure about | the parachutes and the nozzle stearing gear. Still | reportedly it was more expensive to reuse the segments | (basically big metal tubes) than to build new set if SRBs | for each flight, possibly using better techniques | (monolithic carbon fibre overwrapped solid motors, like | on Ariane 5/6). | erulabs wrote: | Oh interesting! Very cool, thanks for the info :) | retzkek wrote: | > s far as I know no solid state boosters were ever re- | used (how would that work?) | | Nitpicking of "reuse" vs "refurbish" aside the SRBs were | significantly reused: | | > The RSRM was designed to make the most use of | recoverable hardware. The majority of metal hardware was | recycled through ATK's Clearfield refurbishment plant in | Utah and returned to a flight-qualified conditioned. | | https://ntrs.nasa.gov/citations/20120001536 | | The boosters used for the final mission, STS-135, even | included parts from STS-1! | https://spaceflightnow.com/shuttle/sts135/fdf/135srbs.pdf | smilespray wrote: | Didn't they reuse the solid rocket boosters for the | shuttle? (Granted, they were delivered by Morton Thiokol | and didn't function well in cold weather...) | [deleted] | redisman wrote: | Lets just say both are doing very important work with very | different incentives | simonlang wrote: | A few years ago I made a mars rover image viewer for a job | interview question. | | Will have to update it if images from Perseverance become | available through the NASA Open APIs. | | https://simon-lang.github.io/mars-rover-image-viewer/#/colle... | iexplainbtc wrote: | That live stream was epic! It was great to see them so happy :) | 0_____0 wrote: | Hard for me to imagine what it's like to spend years of your | life working on a singular launch project. So much riding on | what happens in a handful of moments, whether that's launch or | EDL. Pretty sure I'd just start sobbing in the control room if | that were me regardless of outcome. | iexplainbtc wrote: | These live streams are anxiety inducing for us, I can only | imagine how they must feel! | mrfusion wrote: | I thought they looked anxious and overheated. | ashton314 wrote: | Part of me is sad that I'm too young to have seen the moon | landings. But stuff like this gives me a taste of the thrill of | those days. Congratulations to everybody at NASA. Thank you for | this inspiring endeavor! | throwaway542 wrote: | Fun fact: The rover used software from Bellard's FFMPEG. | chasd00 wrote: | fricken awesome! i love being able to watch these things live. | now i have to get back to work making pixels light up at the | right time and the right color all day long. | WJW wrote: | IT LANDED! | shadowgovt wrote: | Upright and in one piece. :) No, but seriously: amazing | engineering and amazing work. So great to see the images | streaming in already. | WJW wrote: | The skycrane system is just SO COOL. It's also one of those | things that is super easy to explain but incredibly difficult | to actually construct, let alone have it work well after | flying all the way to Mars. | chasd00 wrote: | i can't believe it works. Those thrusters making all that | turbulence and racket. Then the cables have to unwind | without getting tangled and at the same rate. Then, | finally, at the end, they have to detach the cables and fly | away. It's pretty nuts. | tnorthcutt wrote: | They're not _that_ hard to make and fly... in Kerbal Space | Program ;) | | (I'm totally kidding; what they've accomplished is | incredible!) | pupdogg wrote: | It took them approx. 4,881 hours from launch to land approx. | 127,770,000 miles away. Is it safe to say that the average speed | of the mission can be calculated as 436 miles/hour? | mikeyouse wrote: | I think you dropped a thousands somewhere.. 127.8M | miles/4,881hrs = 26,000 mph.[1] | | But in reality, it obviously didn't fly in a straight line, | Looks like it traveled closer to 292 million miles[2], so more | like 60,000 mph.[3] | | [1] - | https://www.wolframalpha.com/input/?i=127800000+miles%2F4881... | | [2] - https://mars.nasa.gov/mars2020/timeline/cruise/ | | [3] - | https://www.wolframalpha.com/input/?i=292526838+miles%2F4881... | pupdogg wrote: | You are correct, I did. Thank you. That's just amazing! | andbberger wrote: | no. hohmann transfer, not a straight line. also there are no | absolute reference frames. | alkonaut wrote: | > also there are no absolute reference frames. | | "Well, officer, perhaps to _you_ it seemed like I was | speeding there... " | mr_toad wrote: | Just, remember that you're standing on a planet that's | evolving And revolving at nine hundred miles an hour That's | orbiting at nineteen miles a second, so it's reckoned A sun | that is the source of all our power The sun, and you and | me, and all the stars that we can see Are moving at a | million miles a day In an outer spiral arm at forty | thousand miles an hour Of the galaxy we call the Milky Way | | - Monty Python. | klohto wrote: | Clean feed here - https://www.youtube.com/watch?v=kPrbJ63qUc4 | | EDIT: Congrats to the team! Great success | johnohara wrote: | Reading you 5 by 5. Thank you. | distortedsignal wrote: | My personal preference is the JPL raw feed (here: | https://www.youtube.com/watch?v=kPrbJ63qUc4) but I think that | more people watching space here is better! Great link! | blach wrote: | From the JPL feed: "My computer was having trouble with Webex, | I'll restart Webex and try the visualization again." | | Hope Percy isn't running Webex. | yellowapple wrote: | I mean, I'd be pretty impressed if NASA managed to get Webex | to run on a 133MHz PowerPC CPU and 128MB of RAM. | winrid wrote: | Are those the hardware specs of this rover? | | EDIT: It's a 200mhz CPU alongside 256mb of ram. | https://mars.nasa.gov/mars2020/spacecraft/rover/brains/ | rpiguyshy wrote: | i wish they would stream the video and audio from the craft live | as it descends to the martian surface | ryankrage77 wrote: | The bandwidth to stream video from mars simply isn't available. | Once it's landed, perserverance must lock onto sattelites | orbiting mars in order to send media back to earth. | GeorgeTirebiter wrote: | Actually, Percy has her own Mars-to-Earth radio. It's that | the high bandwidth is UHF to MRO, MRO to Earth usually (as I | understand it). My guess is they probably could manage a few | FPS at low resolution directly from Percy - but probably | wouldn't do that for power reasons. https://mars.nasa.gov/mar | s2020/spacecraft/rover/communicatio... | gillytech wrote: | What an accomplishment for mankind. Congratulations to NASA, JPL | and the whole team. | m4rtink wrote: | Congratulations! | unanswered wrote: | Something I don't understand: when they say "X is 1 minute from | happening", does that mean it's really 1 minute from happening or | does that mean "in 1 minute we'll receive the signal that X has | happened"? | | Maybe my question makes more sense in the case of "X is happening | right now", because then I should either understand "we infer | that X should have happened right about now" or "we have | confirmed via signal that X has happened", and that's a big big | difference. | | I know in some cases they explicitly say the latter, so I guess | my _real_ real question is, do they just keep the communication | delay implied in all countdowns & references in discussion, to | avoid confusion? | | (ETA: No need to let me know about simultaneity problems in | relativity -- earth and mars are, relative to c and to | macroscopic time scales, essentially not moving relative to each | other AFAIK, so that simultaneity _is_ essentially well-defined. | My question was about a much more boring classical-universe | problem.) | PeterisP wrote: | It's the latter. The Earth-Mars latency at this time is | something like 11 minutes, and the landing itself takes about 7 | minutes, so when we on Earth first saw the craft entering | atmosphere on Mars, by that time all the landing was already | over, one way or another. | interestica wrote: | NASA has a good breakdown of their expected miletones at | 'earth receive time' - https://www.nasa.gov/feature/jpl/nasa- | s-next-mars-rover-is-r... | | Apparently the latency time is currently 11 mins 22 seconds | -- which is somewhere near the average. It goes from under 4 | mins to over 22mins depending on distance. | DiogenesKynikos wrote: | It depends on what coordinate system you're using. Simultaneity | is ill defined in relativity. There's only future, past and | "spacelike-separated" (neither past nor future). When they say, | "X is 1 minute from happening," it's actually neither in the | past nor the future. It's currently spacelike-separated, but in | 1 minute, it will be in our past. | unanswered wrote: | Yes, yes, you have shown you know what relativity is. But the | relative velocity of earth and mars -- which I can't convince | Wolfram Alpha to tell me, but it's got to be on the order of | their orbital velocity so let's say 5x10^4 mph -- is a tiny | tiny fraction of c so their inertial reference frames are | essentially identical. So sitting in our reference frame, we | _can_ make inferences about what 's happening "now" on | mars,such that these inferences are consistent (to within | that tiny fraction of c) with all of our current and future | observations in this reference frame; i.e., consistent with a | classical(+ finite speed of light) model of the universe. | Which is why I left this out of my question and only asked | about the consequences of a finite speed of light. | | Put another way, simultaneity is perfectly well defined in a | single inertial reference frame, and for purposes of my | question, earth and mars can be considered to be relatively | motionless. | jtsiskin wrote: | No, I don't think you're quiet understanding what they are | saying. They aren't talking about the different speeds of | earth or Mars. | | Simultaneity is not "perfectly well defined in a single | intertidal reference frame". That is just a convention. | | If the RTT of earth to Mars is 20 minutes, then we can say | that it takes us 20 minutes for our message to reach the | rover, and the rover's message arrives instantly, and | that's a consistent definition of simultaneity. | | https://www.pitt.edu/~jdnorton/teaching/HPS_0410/chapters/s | i... | unanswered wrote: | Except that an observer located in the | (hypothetical/approximate) common reference frame, but | situated halfway to Mars, will _report_ observations | _inconsistent_ with this definition (NB of course we | receive their report at a time consistent with the | definition, but the contents of the report are not | consistent). So yes, you can play games with your | definition of simultaneity, but you will win stupid | prizes like observers in the same reference frame no | longer agreeing about simultaneity when such a result is | _worse_ than what relativity requires. | | Your link points this out. You _can_ play these games; I | don 't dispute it. But it's a separate matter entirely | from anything to do with relativity, _as your link points | out_ , which is itself separate from the classical | problem I originally posed. So we are now two steps | removed from anything relevant to the Mars rover; I guess | we get a sense of pride and accomplishment? | DiogenesKynikos wrote: | It doesn't depend on the relative velocity of Earth and | Mars. It depends on your coordinate system. You can use | Schwarzschild coordinates centered on the Sun and use the | time coordinate to define simultaneity, but that's an | arbitrary choice. | johncolanduoni wrote: | Now is the part where someone brings up even with the low | relative velocity, you haven't accounted for the | simultaneity issues we'd have if the earth collided with a | black hole while the rover landing was happening. | unanswered wrote: | Or the fact that mars is not as deep in the gravity well | of the Sun! I wonder if they have to account for that one | when programming, like, antenna aiming or something. | minitoar wrote: | IIRC gps suffers about 1hz of blueshift due to descending | into earths gravity. I think the velocity (Doppler) shift | of the spacecraft is a way bigger factor than the | gravitational shifting. | colechristensen wrote: | It looked like they were quoting time as it would appear for an | earth-local observer (i.e. a million light-year away supernova | that showed up five minutes ago happened "five minutes ago" not | 1 million years and five minutes ago. | | With your personal light cone, it's fine to equate "now" with | what you see in the moment. It just has to be clear what you | mean for situations where communication might be ambiguous. If | you have a person on mars, be sure to be precise what you mean | when you tell them to do something in five minutes, when they | receive the message they won't know if you mean five minutes | after they receive the message or anywhere between 17 minutes | before and 2 minutes after they receive the message. | | When you get into relativistic speeds (and especially very | short time intervals), _nobody_ can even agree on when | something "actually" happened, different observers have | different opinions about what happens when even after you | account for light travel time. | extropy wrote: | Relative time (in five minutes) without relativistic speeds | is actually uniform. The is no observable difference to | either participant. | | And there is no concept of now in a significantly distant | location. Related video: https://youtu.be/pTn6Ewhb27k | gfiorav wrote: | Waiting for the physicist in the room to point out: there is no | such thing as simultaneity! | | :) | cambalache wrote: | Oh but there is. Just not in the same frame of reference. | cphajduk wrote: | Depends what type of physicist you ask. | | According to the energy-time uncertainty principle we don't | even know when exactly the RF waves that transmitted | information hit the receiver on Earth either. | whatshisface wrote: | Simultaneity is at least as well defined as clock time. Both | clock time and the velocity of your reference frame can have | arbitrary constants added to them to yield equally valid | coordinate systems. So "it's not really simultaneous" is | analogous to "it's not really 6:30 PM." | bregma wrote: | Well, it's 6:30 PM _somewhere_. | | _lifts glass_ | UnpossibleJim wrote: | From The Hitchhiker's Guide to the Galaxy: "Time is an | illusion. Lunchtime doubly so." | [deleted] | avz wrote: | In the absence of a physicist, I suppose that a software | engineer in the room might do. After all, the | counterintuitive consequences of relativity have their | counterparts in counterintuitive effects in distributed | systems and concurrent programming. In both cases, the core | issue that misleads our intuition is the lack of a shared | global clock that would impose a total ordering [1] on | events/reads/writes/etc. Instead, events in both situations | are only ordered partially [2]. In relativity the ordering is | determined by the speed of light, in distributed systems the | ordering is determined by what messages have been exchanged | by two nodes and in concurrent programming reads and writes | are ordered by synchronization actions such as lock | acquisition and release, memory barriers etc (c.f. the | happens-before relationship in JMM [3] and other memory | models). | | See for example [4] and [5]. | | [1]: https://en.wikipedia.org/wiki/Total_order | | [2]: https://en.wikipedia.org/wiki/Partially_ordered_set | | [3]: https://en.wikipedia.org/wiki/Java_memory_model | | [4]: https://www.youtube.com/watch?v=UYZIHP120go | | [5]: https://www.microsoft.com/en- | us/research/publication/time-cl... | Daho0n wrote: | S/he already did. We just don't know yet. | extropy wrote: | She both did and did not until we observe :p. | | And even that is not correct. Events happening propagate | with speed of light - the event horizon. We can predict we | will receive information of something happening, bit that's | just prediction about future events, regardless of the | location. | fckthisguy wrote: | You can just say "they". | | (Not trying to be judgy. People just seem to forget about | the gender neutral use of "they".) | buzzerbetrayed wrote: | There are like 500 other ways you could have said what | you just said as well. Doesn't mean the way you said it | is invalid. | unanswered wrote: | Why is it acceptable to use the wrong pronoun, such as | "they", for someone who chooses the pronoun "she" or | "he"? | detaro wrote: | They are not talking about a specific person, so how is | "they" wrong? | randomchars wrote: | > used to refer to a person of unspecified gender. | | How is this offensive to anyone?? | unanswered wrote: | For the same reason referring to _anyone_ with the wrong | pronouns is, I would assume. Isn 't that offensive? I | didn't realize this was up for debate in 2021. | randomchars wrote: | But you're not referring to someone with the wrong | pronoun, but using a gender neutral one. | unanswered wrote: | I'm sorry, I honestly don't understand what distinction | you're trying to point out. If someone's preferred | pronoun is "she", for example, and I refer to her as a | "they", then that's the wrong pronoun, isn't it? That's | literally the definition of "wrong", at least the | definition I understand. The right pronoun is "she" and | other pronouns such as "he" and "they" and "it" are, by | exclusion, wrong. | | But it seems like you're saying there's some kind of | complex relation where sometimes people don't get to | choose their own pronouns, but other people get to choose | which one out of many to use based on convenience. Maybe | it would help my understand if you could provide a chart | relating the pronouns someone chooses with the pronouns | other people are then allowed to use? | randomchars wrote: | > Maybe it would help my understand if you could provide | a chart relating the pronouns someone chooses with the | pronouns other people are then allowed to use? | | I think this is everything wrong with the world | currently. Provide you with a chart, so I can justify | using gender neutral pronoun? | | https://apastyle.apa.org/blog/singular-they | | This is barely more than a year old, is it already | outdated? I am an asshole for daring to use "they"? | unanswered wrote: | > If a person uses "she" or "he," do not use "they" | instead. Likewise, if a person uses "they," do not switch | to "he" or "she." Use the pronouns the person uses. | | This matches my own understanding; I have no idea why you | are referring to this article as if it supports your | bizarre crusade to misgender people. | randomchars wrote: | You are aware that we are talking about the mars rover, | right? | | The comment that you replied to: | | > You can just say "they". | | Was a reply to this: | | > S/he already did. We just don't know yet. | | Which was talking about the mars rover. | jonathanstrange wrote: | I'm not a native speaker but the problem I have with it | is that it has the wrong numerus. Although I have done so | in papers recently, because it seems to be a trend, | sentences like _" If a person chose option B, they were | categorized as a cautious assessor"_ seem ungrammatical | to me. (In this case it's easy to reformulate the | sentence in plural and simpler, but that's not always the | case and I hope you get the point.) | frosted-flakes wrote: | If the person is hypothetical or not fleshed-out and | without a gender, like your example, _they_ is fine and I | don 't even notice. But if the person is known, the use | of _they_ catches me off guard every time. I recently | read a book by Brandon Sanderson that had aliens on | another planet with a different gender system, so | Sanderson just used _they_ to refer to those aliens even | though the characters were obviously either feminine or | masculine. It completely broke the illusion of the story | and was a complete turn-off. I _always_ notice in such | cases, but for some reason some people say it 's totally | standard English. | walrus01 wrote: | > simultaneity | | not in the true accurate to the picosecond sense of the word, | no, but the exact word simultaneity is used when discussing | number and density of satellites about a given | latitude/longitude in the starlink beta program. Since | they're LEO and orbiting at only 550 km, the satellites above | a given spot on the ground vary greatly in the not-yet- | complete sparse network. | | Usually related to discussions of whether a beta test | customer terminal will briefly hiccup and lose connection to | its default gateway, or if somebody is at a sufficiently high | latitude that they can have full coverage for all 86400 | seconds in a day. | | https://satellitemap.space/ has a good animated visualization | of this. | theNJR wrote: | Came here to suggest The Order of Time by C Rovelli, which | explains this in such a captivating way. | amelius wrote: | I think this video explains the issue quite well in only | two minutes: | | https://www.youtube.com/watch?v=wteiuxyqtoM | Dylan16807 wrote: | But that only happens with sufficiently high relative | velocities. Earth and Mars are effectively in the same | reference frame. | melenaboija wrote: | Another one here, it is in Catalan but with subtitles in | english. Minute 18 is where it is explained although I | think is worth it to watch all of it | | https://www.ccma.cat/tv3/alacarta/quequicom/tempus-fugit- | sub... | Sharlin wrote: | Yes, those are all Earth Receive Time, that is, when they were | saying that eg. entry interface is two minutes away, in reality | the rover was already sitting on the surface and we were just | waiting for the radio signal to get here. | unanswered wrote: | > Earth Receive Time | | Ah great, that's a great phrase to make everything clear and | provide a kind of "frame of reference" to think & communicate | in. Always need these abstractions. | m4rtink wrote: | The local Czech stream (20k viewers!) I watched went over the | events in real time and then commented how events were | happening as signals were received on Earth - with the final | confirmation of successful landing coming first via Twitter, | no less! :) | | Still a very nice yet nerve wrecking idea to do it like this | - you _know_ the lander is on Mars _now_. But is it safely on | the ground or is there a third Shapirelli crater now ? You | don 't know! A huge relief in the end. :) | matt-attack wrote: | But aren't those two events essentially simultaneous in the | relativistic sense? That is by some definitions of | "simultaneous"? | zwkrt wrote: | In one sense, light experiences no time during travel, so | anytime you are hit by radiation (like from a star) there | is frame of reference in which the event was instantaneous. | | On the other hand, if you were on Earth and I was in | between Earth and Mars, I would receive the data more | quickly than you, and I could even watch it whiz by me on | its way to you. The thing about relativity is that it's... | relative! | OliverGilan wrote: | Doesn't relativity tell us it doesn't matter? | cjohnson318 wrote: | There's a lag time in communication due to distance. I don't | see what that has to do with relativity. | runarberg wrote: | PBS Space Time recently explained what the present time means | within general relativity[1]. As I understand it... it | matters in this context. | | [1]: https://www.youtube.com/watch?v=EagNUvNfsUI | scotty79 wrote: | True fun begins when you consider General Relativity (which | takes into account gravity and acceleration). From what I | heard there is no definition of simultaneity and you can | define it in different ways. | runningmike wrote: | I never forget a great fosdem talk regarding living on mars. | https://archive.fosdem.org/2015/schedule/event/living_on_mar... | unfortunately it turned out to be a hoax. | sidcool wrote: | Touchdown confirmed!! Congrats NASA. | mu_killnine wrote: | The Nasa person they have helping narrate what's going on is so | genuinely happy the landing went well. It made me kinda tear up. | It's infectious just how excited all these people are about this | project. Also, I was a bit worried he was going to pass out. | 10/10, would watch again (and probably will with my kids) | shadowgovt wrote: | The audible _whew_ from one of the crew members after maximum | deceleration when the telemetry re-established was heart- | rending. Years of work, and there 's nothing anyone here can do | eleven light-minutes away; it was either going to work or one | of the thousands of things that had to happen correctly wasn't | going to happen. | | Everything happened correctly. :) | [deleted] | electriclove wrote: | This guy? | https://www.youtube.com/watch?v=gm0b_ijaYMQ&t=1h41m36s | | That is Rob Manning, an absolute legend! Here is an interview | with him from a few years back: | https://solarsystem.nasa.gov/people/2280/rob-manning/ | | He also wrote this great book: https://www.amazon.com/Mars- | Rover-Curiosity-Curiositys-Engin... | tomc1985 wrote: | I love the fact that you could hear people saying things like | "yes yes yes YES YES!" in the background as data came in. Like | you say, very infectious | Azrael3000 wrote: | It's a great achievement with some really interesting work done | on the landing algorithms with terrain recognition and it seemed | to have worked exceptionally well. | | Looking forward for the next landing in May of the Chinese rover | and all the science these robots will produce. Also, the test of | Ingenuity, the helicopter, will be very interesting to watch, | that could really pave the way for a different exploration style | in the future. | | And finally, maybe the next transfer window will already see some | Starships, that would really change everything. | jaegerpicker wrote: | Ingenuity is maybe the most interesting and coolest advance for | space travel. The idea of a remote drone to explore Mars is | just rad! I can totally nerd out about that! | suyash wrote: | More about Ingenuity | https://spectrum.ieee.org/automaton/aerospace/robotic- | explor... and it's source code https://github.com/nasa/fprime | jvanderbot wrote: | That is not Ingenuity's source code, that's the software | framework used to link the various software modules. It's | generic to any mission / instrument. | suyash wrote: | correct | kibwen wrote: | A great video where the host visits the drone, interviews its | makers, and goes over the cool technical aspects of it and | its mission: https://m.youtube.com/watch?v=GhsZUZmJvaM | jvanderbot wrote: | You may be interested in dragonfly then: | https://www.nasa.gov/dragonfly | jws wrote: | Early starships got me thinking: given the high likelihood of a | failed starship landing, and maybe having the ability to send | one before fully engineering a payload... | | What would you ballast a starship with for the practice | missions? | | Useful materials which might survive a RUD and aim for | someplace near a likely landing zone? If you crash the parts of | a milling machine, a lathe, some tooling, some assorted metals | stock, and a bunch of assorted wire, well sure you just cleared | out a machine shop auction, but maybe there comes a day when an | early Mars colony would be thrilled to go clean up your | "landing" site. | gameswithgo wrote: | we playing factorio here? | L_226 wrote: | Soil? Though not sure it is prudent to potentially spread | active biological material all over a pristine (eco)system. | danw1979 wrote: | Water. | blackrock wrote: | Don't litter Mars Elon. Stick your landing. LOL. | mikewarot wrote: | Why not work on some very small machines that can mine and | refine materials to make more of themselves? | george3d6 wrote: | Because "refine" really means "melt at temperatures ranging | from 500 to 4000 degrees celsisu and then extract via | various mechanical processes and/or using various reactants | which often require gigantic plants to produce and are | highly unstable". | | Basically all of the history of science until 200 years ago | was figuring out "mine and extract" and the course of | civilization is very much linked with the price & quality | of metal structures they could produce. But it's gotten so | good we take it for granted. | | However that is because of gigantic plants situated in | specific areas where energy is cheap that do this thing at | an amazing scale. | | Aluminum is cheap as chips, except that it used to be more | expensive than platinum (and at a much higher impurity | ratio than the stuff we use for baking or for making cheap | cases). | | Heck, gold is "a thing" because we could purify and mold it | without bringing it to a melting point and it was, for a | very long time, the only metal available to us to do | anything with, way before the bronze age. | | And the problem with the refinement process is that you | can't really "be smart" about it, reaching very high | temperatures is one of those things you can't really scale | down in an efficient way. You'd have to propel 100,000 tons | of factory to mars in order to efficiently refine anything | remotely close to the metals we had access to 100 years | ago. | | Which is not to touch on the mining bit, that is in itself | very complicated (see how slowly and shallowly rovers are | currently able to drill). | | Are there workarounds for this? Maybe, I don't think anyone | knows them though, they are not the kind of thing that's | within easy reach. Maybe if we happen to stumble upon large | reserves of bismuth or lead or gallium or mercury close to | the surface of Mars, and build a whole branch of | engineering around using those to build machinery... ? But | my limited knowledge of geophysics and geology tells me | that finding those in large amounts is very unlikely. | | For reference, if you take an oven, that can reach, say, | 450 degrees celsius (home) and up to 700 (industrial). | Those aren't enough to refine any "useful" metal (e.g. | iron) and building them requires materials that were | produced at 1500+ degrees. | | IANAChemist/IANAMaterialScientist/IANABlacksmith though, so | take with a spoon of salt. | mikewarot wrote: | We don't have to be efficient, just small and reliable, | no matter how slow... if there were enough small machines | to turn out enough materials to build new ones faster | than the failure rate, then geometric growth wins, and | you can build whatever you want, eventually. | zo1 wrote: | It could be something very low-tech even. Just a machine | that turns solar-energy + some mechanical power into say | mars-dust bricks, non-stop for use in future missions? | Maybe something that just keeps digging a perpetually | deeper and deeper trench in a straight line so that | subsequent missions don't need big drills to find out | below-surface samples? | | But thinking about it now, I can't envision that we here | would be able to come up with something sublime/novel | that a huge army of really-smart people haven't already | after spending decades thinking about it. Then again, we | have a lot of smart people concentrated in this forum, so | who knows if a weird/silly conversation triggered by IT- | minded people, acts as a catalyst for the engineer- | lurkers that see it. | george3d6 wrote: | I don't think you're getting my point, consider reading | again. There's a fundamental limit you will hit here, you | can't just "make it slower" or "make it worst" to lower | that limit. | mikewarot wrote: | There is a fundamental limit of power... I get that. The | Perseverance Mars Rover has one experiment that requires | 180 watts of power, (The Oxygen Generator experiment) and | it has a 110 watt RTG powering everything. They charge up | some lithium batteries during down time, and use them to | make up the difference. | | In the limit, If something takes 5,000 watts, you could | run it for a few minutes/day, with that same RTG, | provided you had suitable energy storage. | | Perhaps they could gather grains of material, and just | sort them, one at a time, only keeping the iron rich | material, or use a permanent magnet to gather ferrous | material. You could sinter the grains together using a | microwave or laser pulse. | | The results don't need great quality, just enough tensile | and compressive strength to be mechanically stable during | additive or subtractive manufacture. | | Lots of minds have been thinking about refining metals | for a very long time, but they haven't been thinking | about doing it on Mars, with limited power, and very far | outside the box of normal constraints, like cost. | | This is one time capitalism doesn't apply at all... and | most solutions assume capitalist incentives and costs, | instead of going back to first principles thinking. | saberdancer wrote: | Bunch of 2x4s and screws/nails :D. | skapadia wrote: | Great, humans are starting to accumulate trash on Mars before we | even step foot. Descent stage, heat shield. Pile it up! | chasd00 wrote: | heh my 11 year old quipped "i bet the martians are like 'these | guys!? again??'". it made me laugh pretty hard | huhtenberg wrote: | First surface photo is in too! | | https://i.imgur.com/C2s1job.jpg | kaycebasques wrote: | N00b question: why is it black & white? | nwallin wrote: | Other posters have pointed out that it's the hazard avoidance | camera, but they haven't said why the hazard avoidance camera | is black and white. | | When you do computer vision, the first step you do is convert | your color image into a black and white image, and run your | CV algorithms on the black and white image. This is because | when you're looking at objects and shapes and stuff, it's | contrast that tells you where the boundaries between things | are. This is true even in a human world of human objects, | which tend to be many colored. It's even more true on Mars | where basically everything is varying shades of orange. So | having color doesn't help a whole lot, and you also have to | do the additional step of converting the color image to black | and white, which takes CPU power and adds latency. Remember, | the purpose is hazard avoidance- latency is bad. | | Additionally, color camera sensors aren't actually color | sensors. They're black and white sensors. In front of every | pixel on the black and white sensor is a filter that is | either red, green, or blue. Pixels are grouped into sets of | four, and there are two pixels with green filters, one pixel | with a blue filter, and one filter with a red filter. | (sometimes one of the green filters is omitted, giving red, | green, blue, and b&w, or sometimes one of the green filters | is a filter that allows IR, or something like that.) So if | you have a 16MP camera, the camera has 8M green, 4M red, and | 4M blue pixels. This means two things; first of all, if you | just wanted a black and white image in the first place, a | color sensor gives _less_ detail than the equivalent black | and white sensor, and second, you need to do additional | processing to convert the raw output from the sensor into an | image that 's usable for anything. The additional processing | adds latency. | whuffman wrote: | Just as a heads up, the HazCams on Perseverance are in fact | in color (Source: https://link.springer.com/article/10.1007 | /s11214-020-00765-9 - "The Mars 2020 Navcams and Hazcams | offer three primary improvements over MER and MSL. The | first improvement is an upgrade to a detector with | 3-channel, red/green/blue (RGB) color capability that will | enable better contextual imaging capabilities than the | previous engineering cameras, which only had a black/white | capability.") Your observations are correct though - the | stereo precision is important, so there was additional | analysis of the stereo depth computation to make sure it | wouldn't cause an issue. | nwallin wrote: | Huh, I guess so. Looking over the study it looks like | they had issues by looking at dirt in scoops and being | unable to tell whether it's Martian dirt or a shadow. | | I have a feeling I'd be the angry guy in the meeting who | wouldn't accept the consensus. "but what about latency! | what about the descend and landing!" _shakes fist_ | rmonroe wrote: | Nah, your concerns are 100% reasonable - they just | operate on a different context. On Earth, latency is | king. On Mars, especially until the Primary Mission is | complete, it's all about risk mitigation. Since we're | light-minutes away from Earth, a few frames of latency is | nothing. At the same time, you want to avoid breaking | your $3B machine, which is hard to operate given the | time-of-light delay and comms limitations. Just a | different set of tradeoffs. IIRC they first tested on- | device deep learning for hazard avoidance in Curiosity, | but don't quote me on that. | | -Worked at JPL for a few years and have dozens of | friends, a few in the vision system. | kharak wrote: | Thank you for the explanation. That was highly interesting. | Does anyone else know if the human eye does perceive color | directly? Is this at all technically possible? And if yes, | why aren't we doing it with cameras? | ddingus wrote: | I believe in purple. | | After you get done exploring how we perceive colors | associated with different wave lengths of light, and how | nobody really knows whether these are common somehow, or | unique to each of us, that sentence should bring you both | a chuckle and some wonder about perception. | Koshkin wrote: | From the physiological standpoint human individuals are | far, far from being unique. The electrochemical reaction | of a neuron in the cortex which indicates the perception | of 'red' is pretty much the same in any human (and not | only). | ddingus wrote: | Whether that subjective perception is the same remains | unknown. We have no solid way to communicate any of that | yet. | | I am inclined to believe it is, but we do not really | know. | natosaichek wrote: | What do you mean by "directly"? Color is a human | abstraction over the reception intensity of certain | wavelengths of light. | Koshkin wrote: | What do you mean "abstraction"? The colors that I am | seeing look very concrete to me. (Also, the "wavelength | theory" of color perception does not explain why TV | screens work.) | natosaichek wrote: | The human retina is composed of cells that are responsive | to different wavelengths of light. Color is the word that | we use to describe the subjective sensations associated | with certain patterns of stimulation of those cells. | There is no "yellowness" in a bananna. We cannot | construct an instrument capable of measuring "yellow" as | such. What we can measure are the intensities of | wavelengths of light. | | We can notice that when people say they perceive "yellow" | that the spectral intensity graph has certain patterns. | This is the physical phenomenon that produces the | sensation of "yellow." | | Humans are not good at judging reality introspectively. | We experience everything heavily filtered through a | variety of lenses. Our feeling that color is "concrete" | is not predictive or explanatory... we cannot build | mechanisms based on it. The idea that our perception of | color is a result of interactions between certain | wavelengths of light and certain photosensitive tissues | in our eyes is both predictive and explanatory. We can | design systems that have similar types of wavelength | intensity sensitivity components and measure the physical | response of those systems. That's how cameras work. | | We can reverse the process and take those measured | wavelength intensities and re-emit them from variable- | wavelength light sources and produce images. That's how | you're reading what I've typed right now - the images | produced by the display you're looking at were generated | in this fashion. | | I'm not sure what you mean by the "wavelength theory" of | color perception. | Koshkin wrote: | > _We cannot construct an instrument capable of measuring | "yellow" as such._ | | Of course we can. We can capture the signal sent through | the optical nerve and then reproduce it as a stimulus | which will make the brain "see" yellow color. | | Besides, humans are capable of distinguishing literally | millions of colors, of which just a tiny fraction can be | attributed to measuring particular wavelengths (or, more | accurately, particular energies of the incident photons). | In that way the eye is different from the ear (which | performs a kind of Fourier analysis of the sound wave). | natosaichek wrote: | Well, the instrument wouldn't me measuring yellowness... | it would be measuring electrical impulses that (in some | individuals) correspond to the (verbally asserted) | perception of "yellow". "Yellow" is not a characteristic | of the world; it's a convenient label that humans apply | to some bucketed sets of sensory perceptions. | | I agree that there are sensory perceptions humans are | capable of perceiving and labeling as colors that cannot | be attributed to external physical phenomena, but those | are largely artifacts of the way our brain processes | signals. For example if you stare at a purple dot for | some time, then look away, you'll perceive a yellow dot | where there is no external set of photons corresponding | to the wavelengths that normally trigger the sensation of | yellow striking your retina. | | This is just more explanation about how "yellowness" is a | characteristic of our brains, not of the external world. | | Or did you mean something other than what I'm referring | to here? I think that for the vast bulk of humans, the | vast bulk of the colors they perceive regularly are due | to photons striking rods and cones in their eyes at | various intensities, causing color sensations to occur in | the brain. Do you think something else is happening? | | You seem to understand how the eye works, and some | neuroscience, so I don't understand how you can have the | questions that you raise about whether we can build | cameras that sense "color" instead of "light" | zinekeller wrote: | Short answer: No. We (the majority anyway, as some are | colourblind) only perceive lightness, reddish, greenish, | and bluish. The brain uses the info and effectively | synthesises the image in our brains. | | Long answer: Colour is a very rabbithole topic but | Captain Disillusion has a summary of it | (https://youtu.be/FTKP0Y9MVus) and Technology Connections | has a discussion (https://youtu.be/uYbdx4I7STg). | nwallin wrote: | ...it's complicated. Very complicated. However | complicated you think it is, it's more complicated than | that. Please note that I'm not an expert in human eyeball | physiology, I'm just a computer programmer who's tried | pretty hard to come to a better understanding of how to | make computer vision better. (I've failed, fyi. Caveat | emptor.) | | The human eye has four basic cell types, rod cells and | cone cells, and there are three subtypes of cones, short, | medium, and long. The three subtypes of cone cells sense | blue, green, and red light more or less directly. Medium | and long cone cells, which directly detect green and red | light, almost entirely overlap. [0] It is more accurate | to say that long cone cells detect yellow light than it | is to say it detects red light. There is a brain system | which measures the difference in response between the | long (red) and medium (green) cells and uses the | difference to say "aha! this must be red!" | | The ratio of short (blue) medium (green) and long (red | (yellow)) cone cells are roughly 2%, 2/3, and 1/3. The | cells in your eye which detect blue light are more or | less a rounding error. The cells which detect green light | are roughly twice as numerous as the cells which detect | red (well, yellow) light. If you see a thing and think, | "man, that's awfully blue," it's not because your eyes | are telling you "hey, this thing is awfully blue". The | "blue" signal is barely noticeable in the overall signal; | but your brain jacks up its responsiveness to the | minuscule blue signal. | | One of the side effects of the completely fucked ratios | between the three types of cones is that your perception | of the overall brightness of a thing is mostly down to | how green it is. This shows up in lots of standards; | NTSC, JPEG, the whole nine yards. If you've ever | implemented a conversion between RGB and any luminosity- | chroma colorspace (YUV, YCbCr, YIQ, NTSC, any of them) | there's a moment where you'll go "wait a minute this | doesn't make any fucking sense". You look at the numbers | and the luminosity channel is just... green, and you know | that the other two chroma channels are quartered in | resolution. And you'll think that makes no sense. But | that's how it works. | | Then you'll remember that color sensors have their pixels | arranged in groups of four, with two green, one red, and | one blue channel. There must be some green conspiracy. | | And there is. It's your brain. It's your eyeballs with | 2/3 of its cone cells being green sensitive ones. | | Those are your cone cells. Rod cells are entirely | different. It's trivial to say well, cone cells see | color, rod cells see black and white, but it's more | complicated than that. Rod cells are excellent in low | light conditions, cone cells not so much. Cone cells see | motion very well, rod cells not so much. Cone cells can | discern fine detail, rod cells do not. Rods and cones are | not evenly distributed across the retina either; cone | cells are densely packed in the center, rod cells are | more common in peripheral vision. | | Look at a colorful thing directly; take a note of how | colorful it is. Now look away from it, so it's only in | your peripheral vision; take a note of how colorful it | is. Does it seem just as colorful? It isn't. That's your | brain fucking with you. Your brain knows it's in your | peripheral vision and all the colors are muted out there, | so your brain exaggerates the colorfulness. Cone cells | are 30 times as dense in the center of your vision as | they are just outside the center of your vision. [1] | That's why you can read a word directly where you're | looking but it's very difficult to read elsewhere. | | The reality is that your retinas give a fucking mess of | bullshit to your brain, and the brain is the most | incredible image processing system conceivable. It takes | bullshit that makes no damn sense and -- holy shit I | forgot to talk about blind spots. | | Ok, so your rods and cones have a light sensitive thing, | with a wire in the back, and all the wires get bundled up | in the optic nerve that goes to the brain. Here's the | thing: they're fucking plugged in backwards. The wires go | forward, and are bundled up between your retinas and the | stuff you're looking at. The big fat optic nerve | therefore constitutes a large chunk of your vision where | you can't see anything. Your brain just.. _invents stuff_ | where the optic nerve burrows through your retina. | | Other weird stuff. If it's bright, the rods and cones | send no signal, if it's dark, they send a strong signal. | It's inverted. There's apparently a very good reason for | this but I don't remember what it is. Also, the rods | continuously produce a light sensitive substance that | amplifies the light sensitivity but is destroyed in the | process. It takes a long time to build up a reserve. This | is why it takes time to "build up" your dark vision, and | why it's so easily destroyed by lighting a cigarette. The | physiology of "ow it's bright" as opposed to "it's | bright" isn't just on your retinas, it's also on your | eyelids and your iris, but more importantly, it's shared | between your two eyes. This is why closing one eye makes | it less painful when you go from a dark place to a bright | place. | | The point is, the study of human vision is not the study | of the human eye. The study of human vision is the study | of the human brain. | | Much of what we do with color spaces and image | compression is dictated by our stupid smart eyeballs and | our stupid smart brains. Video codecs compress with 4:2:0 | chroma subsampling because the brain's gonna decompress | that shit better than a computer can anyway. Cameras have | twice as many green sensitive pixels as blur or red | pixels because the eye resolution is much sharper in | green than other colors. More advanced image and video | compression schemes will try harder to account for human | eye-brain physiology. | | [0] | https://upload.wikimedia.org/wikipedia/commons/0/04/Cone- | fun... | | [1] https://upload.wikimedia.org/wikipedia/commons/3/3c/H | uman_ph... | POiNTx wrote: | My guess is lower image size, which means image can get | transferred faster. | txg wrote: | This is the right answer. The camera (and its 8 siblings) | are capable of color HD imaging - the sensor has a Bayer | filter. This image used a binning mode to produce a | downsampled frame that could be more rapidly transferred | back over the lower bandwidth comms used during landing. | Binning combines the Bayer pattern and so color information | is lost. | | Also doesn't help that there is a (transparent) lens cover | in front of the lens obscuring the view. | Azrael3000 wrote: | That is most certainly correct. They also mentioned that | these are images from engineering cameras, so they are | normally responsible for navigation. The real HD footage | will come in over the next hours as the bandwidth just is | not large enough. | | Elon Musk needs to provide some Starlink sats for a better | connection. | _Microft wrote: | Starlink would most certainly be of little direct use | here. | | What I could imagine is having Starlink satellites around | Mars that allow to route data from rovers anywhere on the | planet to a dedicated high-performance communications | platform that handles communication with Earth. | teraflop wrote: | In fact that's exactly what they're doing: the Mars | Reconnaissance Orbiter is serving as a communications | relay, as it did for previous landers. | | It's just that since there have never been more than a | handful of spacecraft active on Mars at any given time, | there's currently no point in spending huge amounts of | money to launch a whole constellation of satellites for | continuous coverage. | Sharlin wrote: | Not only the MRO, but other orbiting assets as well, | particularly NASA's MAVEN and ESA's TGO. Even the | venerable 2001 Mars Odyssey is still used as needed, I | think. | m4rtink wrote: | Even ESAs Mars Express is still around - since 2003! | davidmr wrote: | And a photographer! MRO took what might be my very | favorite picture of all time: | https://www.space.com/16946-mars-rover-landing-seen-from- | spa... | m4rtink wrote: | Could be still a nice exercise if someone could compute | how many Starlinks could a Falcon Heavy throw to Mars | transfer orbit & if they could be able to actually | capture into Martian orbit by their default means of | propulsion (do they actually have any high thrust engines | ?). | nothis wrote: | Anyone know the bandwidth they're working with, at least | roughly? | kibwen wrote: | Here's a page with data about the Deep Space Network: | | https://mars.nasa.gov/msl/mission/communications/#data | | _" The data rate direct-to-Earth [from Mars] varies from | about 500 bits per second to 32,000 bits per second"_ | zokier wrote: | Clarification, that is for the old Curiosity rover. The | page for Perseverance has some additional information | | > 160/500 bits per second or faster to/from the Deep | Space Network's 112-foot-diameter (34-meter-diameter) | antennas or at 800/3000 bits per second or faster to/from | the Deep Space Network's 230-foot-diameter (70 meter- | diameter) | | for high-gain antenna, and | | > Approximately 10 bits per second or faster from the | Deep Space Network's 112-foot-diameter (34-meter- | diameter) antennas or approximately 30 bits per second or | faster from the Deep Space Network's 230-foot-diameter | (70-meter-diameter) antenna | | for the low-gain antenna, which I believe the first two | images were sent through | | https://mars.nasa.gov/mars2020/spacecraft/rover/communica | tio... | m4rtink wrote: | Maybe it was the low gain antenna but via MRO or other | orbiter? 30 bits per second seems like a bit too slow to | get even the two small images back so quickly. | extropy wrote: | That's rover directly to earth, when reconnaissance | orbiter is used to relay it's around 2 mbit to orbiter. | smilespray wrote: | It's from a hazard camera, which is not used for main | photography. Better images will come soon. | ehsankia wrote: | Worth noting that these first pictures are sent in the | first seconds after touchdown, you can even still see the | dust in the air from the landing (even if it was craned | down to reduce dust). It also explains the very low | resolution in general, they want to get confirmation ASAP, | no time for high quality high resolution images. | nerfhammer wrote: | would dust stay in the air longer or shorter than on | Earth? | | also is it technically correct to call the Martian | atmosphere "air"? | DonHopkins wrote: | Yes, but it's not technically correct to call Martian | seismic tremors "earthquakes". | | https://www.imdb.com/title/tt0080745/goofs | | Flash Gordon (1980) Goofs | | At the very beginning of the film, Ming and his henchman | are discussing "an obscure body in the SK system", which | the inhabitants refer to as the planet "Earth", | pronounced as if the word is completely foreign to them. | However, at that moment, Ming activates a button on his | console labeled "Earth Quake". | | http://bobcanada92.blogspot.com/2020/10/flash-gordon- | logic.h... | nerfhammer wrote: | Star Trek calls them "quakes" I noticed | ajross wrote: | Dust falls much, much faster on Mars. The density of | Mars's surface atmosphere is ~160x lower than on Earth. | mrec wrote: | Right. One "proof" advanced by Moon landing conspiracy | theorists was that dust settled much faster in videos | than it should if it were _really_ in Lunar gravity. | js2 wrote: | Miriam Webster says yes to part two: | | > the mixture of invisible odorless tasteless gases (such | as nitrogen and oxygen) that surrounds the earth | | > also : the equivalent mix of gases on another planet | | I would naively guess yes to part one but it's | complicated: Mars has less gravity, much less atmospheric | pressure, colder temps, and greater gravitational | influence from its moons than Earth. Wikipedia says the | mechanism of the planet's dust storms isn't well | understood. | | https://en.wikipedia.org/wiki/Atmosphere_of_Mars#Dust_and | _ot... | themeiguoren wrote: | The low resolution and fuzz is also because they still | have the lens caps on - they are of course transparent | lens caps in case the explosive bolts that will release | them fail. Redundancy! | interestica wrote: | This is one of the cooler things that I learned today. | Could they go even further: make the caps themselves | lenses+filters. Take photos. And then blow them off for | new photos. | [deleted] | hiharryhere wrote: | I heard on the live stream that it was taken by a camera that | is used by the driving system. | | Guessing its black and white/high contrast to help see rocks | etc. And probably much lower res, smaller file size too for | transferring. | ijustlovemath wrote: | Just an enthusiast, no real answers, but here's a guess: | | These are hazard cameras, designed to be inputs into the | guidance algorithms on board. It might make sense for such a | camera to be B/W to reduce on board processing required. | There's also a glass cover on them, and a lot of dust from | the landing, so that may be obscuring true color if the | cameras do in fact take color images. | | Also they may have just transmitted a lower quality B/W image | to get something back to Earth quickly, since higher res | images take longer to uplink. | neals wrote: | It's an "engineering cam" that's not really meant for taking | nice pictures, more to see where the thing is going. There'll | be some better Instagram selfies soon though. | [deleted] | robinjfisher wrote: | This was explained on the feed. It's from a lower-res safety | camera mainly used for object avoidance on the ground. High | definition images will be available later. | interestica wrote: | https://mars.nasa.gov/mars2020/multimedia/raw-images/ | | It seems that NASA is being awesome and making all raw | images available as they get them. So far just the 2-ish. | handedness wrote: | The world is a complicated place, Hobbes.[1] | | The lower "HazCams" hazard avoidance cameras (which captured | those initial photos) are there to detect hazards (rocks, | trenches, etc.). They are stereoscopic, lightweight, and high | resolution. | | My guess is that using color sensors would have either | increased the 3D mapping precision or added | weight/power/bandwidth requirements, or otherwise been less | robust in that environment. | | Those cameras were also pre-deployed for the landing phase | and likely transmit more quickly due to the lower data | information. The other cameras were shielded for the landing | phase. | | The navigation and other cameras are in color, and I expect | we'll be seeing better images shortly. | | [1] This comes to mind whenever a question like that is | asked: http://4.bp.blogspot.com/-CWM1zDcmWXs/TroD0VsX4WI/AAAA | AAAAAV... | whuffman wrote: | FYI - the HazCams on Perseverance are in fact in color | (this is new, they were black and white on Curiosity)! | Stereo precision was a concern based on the switch to color | sensors, so there was some algorithmic work done to make | sure it wouldn't cause an issue. (Source: https://link.spri | nger.com/article/10.1007/s11214-020-00765-9 - "The Mars | 2020 Navcams and Hazcams offer three primary improvements | over MER and MSL. The first improvement is an upgrade to a | detector with 3-channel, red/green/blue (RGB) color | capability that will enable better contextual imaging | capabilities than the previous engineering cameras, which | only had a black/white capability.") | handedness wrote: | Interesting, I didn't know that. I knew the Cachecam was | color, but somehow missed that detail, despite actually | seeing the camera in person at one point... | m4rtink wrote: | Wow, real upgrades all around compared to Curiosity! | | What are they going to do next ? Put on board a solar | powered Mars helicopter ?? ;-) | jxcl wrote: | > My guess is that using color sensors would have either | increased the 3D mapping precision or added | weight/power/bandwidth requirements, or otherwise been less | robust in that environment. | | I think you meant to say decreased? In which case I think | you would be correct! Camera pixels are made up of these | things called photosites which don't by themselves record | color, only brightness. In order to record color | information, the photosites are placed behind a Bayer | filter[1], which effectively reduces the resolution of the | camera by 3, because in order to get the color of a pixel | you need its red, green and blue component. Bayer filters | also frequently have a small blurring filter in front of | them to make sure that nearby photosites with different | color filters get the information they need. | | If you're looking for the highest resolution image | possible, black and white is the way to go! | | [1]: https://en.wikipedia.org/wiki/Bayer_filter | m4rtink wrote: | That's why "real" space cameras usually have color | filters on a carousel before the sensor - they take 3 | pictures each with different filter and BAM, color! | | That way you get high regulation as well as color. You | can also have some special (infrared, ultraviolet, etc.) | Filters on the carousel, not just RGB. | dylan604 wrote: | >and BAM, color! | | and BAM, false color! FTFY | handedness wrote: | > I think you meant to say decreased? | | I did, thank you. I think my brain had already skipped | ahead to the added weight/complexity concept while my | fingers were stuck on that part of the sentence. | | I should probably read things after I type them... | handedness wrote: | And by "increased" I meant the "decreased" kind... | kube-system wrote: | Here's the answer from NASA: | https://youtu.be/gm0b_ijaYMQ?t=6240 | ArtWomb wrote: | Greetings from Jezero Crater! Really doesn't look alien. RLike | the high mesa of New Mexico sans flora ;) | gillytech wrote: | The shadow features are fantastic! | interestica wrote: | NASA is making the raw images of everything available: | | https://mars.nasa.gov/mars2020/multimedia/raw-images/ | ape4 wrote: | Today's images are from Sol 0. Zero-based counting rules. | mam2 wrote: | live or fear.. you have to chose | ortusdux wrote: | They have a live telemetry animation web app, but I am currently | getting a 503 from cloudfront. | | https://eyes.nasa.gov/apps/mars2020/ | shadowgovt wrote: | Yeah, it was accessible until they mentioned it in the | livestream. | | To their credit, I've watched NASA spend decades getting better | at Internet services and generally being an online presence. | Improvements year-over-year have been noteworthy. But I still | have to chuckle a little bit that they triggered a DDOS protect | by name-dropping themselves. | | Ad Internet Per Aspera, you crazy spacers ;) | raylus wrote: | Thanks!! Also wanted to mention, NASA is separate from JPL | for the most part as far as web services go. | shadowgovt wrote: | Great work today. | mhh__ wrote: | The telemetry they have up on the wall is based off a project | that they have open sourced too (Open MCT), or at least it | looks like it. | alach11 wrote: | Watching the stream, it's striking the difference in employee age | between NASA and SpaceX. I won't speculate on the reasons, but I | wish the best to the Perseverance team! | shironandon wrote: | unsure why you think that is relevant, bub. Interested in their | religion, political views, and sexual preferences as well? | klohto wrote: | Stop picking up fights, that wasn't the point of the comment | at all. | johnchristopher wrote: | I thought they were young people in the NASA video. Does that | mean people at SpaceX are older ? | flyinglizard wrote: | It's also remarkable that the NASA workforce is 99% women, as | evident from this broadcast. | chasd00 wrote: | hah they probably don't let the kids near the really important | buttons ;) | dharmab wrote: | Remember that not all the staff could be at NASA today due to | COVID policies. Most of the team is at home. | avereveard wrote: | I don't think the video show a representative sample of the | employee at either company; I suspect picks where selected for | stage presence with a touch of preference for diversity. | tambourine_man wrote: | https://www.youtube.com/watch?v=gm0b_ijaYMQ | | Live feed | ggm wrote: | Here in oz its not live | meepmorp wrote: | I guess technically it's on an 11 minute delay for the whole | planet. | ggm wrote: | Well yes, but I meant I watched continuously from 06:45 to | 07:15 and it was replay of pre-recorded videos of the rover | and no indication on screen it had landed. | rablackburn wrote: | odd, I'm in Aus too and I watched the entire thing live | with no issues (assuming you're in QLD on EST) | ggm wrote: | I am. Maybe I turned away at the wrong crucial 30 | seconds. | | (Edit) I checked the JPL clean feed and none of the last | two hours of feed is what I saw being sent on NASA live. | I got a walk around the robot, and social media about the | kids who named it, and talking heads. Bizarre. | jaegerpicker wrote: | Seeing the engineers and scientists celebrating the successful | landing was one the best things I've seen in a LONG while. Very | live affirming and inspiring to me! | BurningFrog wrote: | Is part of the joy that they now have secure jobs for years to | come? | soheil wrote: | Most common assumption by outsiders is that they're happy | that their many years of effort came to fruition, but I think | a big part of is that they will be working on this mission | for the foreseeable future as you point out. They get to tell | their kids I worked on this mission, it was successful and | then we made the rover do X, Y and Z in the next few years. | AnimalMuppet wrote: | I think it's mostly the joy that their past decade or two of | work wasn't wasted. | jaegerpicker wrote: | Maybe but for me I think it would the joy of completing such | a massive task so well. They literally just achieved | something that no one else in history has. | acomjean wrote: | It is the fifth rover... But still super impressive feat, | with years of detailed planning. I boogles my mind thinking | about all the bits of engineering put together to make this | happen. | | I can't wait to see what it sends back. Always celebrate | your successes. | Rebelgecko wrote: | I wouldn't be surprised if a lot of the engineers who worked | on EDL move on to other projects in the coming weeks | notum wrote: | Any JPL/NASA HN users that could comment? That would be beyond | awesome! | | Great job, mission! | raylus wrote: | JPL Engineer here, any questions I could convey to the slack | I'll be glad to feed back to HN | m4rtink wrote: | How much overlap is there now that two similar yet 10 years | different rovers are in operation ? Is it possible to share | some of the human/software/planning resources or are they | basically two separate efforts by this points ? | | Also, do the Rover Drivers still live on the Mars time that | makes their working hours shift by 45 minutes every day, like | in the good old MER days ? ;-) | Nekhrimah wrote: | Any idea on the timeframe for unfurling the robotic arm? And | doing the test drive? | | Thanks for your efforts towards the fantastic result today. | prox wrote: | I just want to thank you all for the wonderful time tonight, | we've been watching with the family. Amazing accomplishment! | myself248 wrote: | "Slack" is actually the answer to one of the questions I was | going to ask, about internal communication! | | Hmm, another: Given that it's roughly a decade since MSL | Curiosity, what were y'all (Perseverance team members) doing | when Curiosity launched and landed? How many of today's team | were in school back then, or what's the generational turnover | and overlap like? | | What's everyone's "favorite" failed Mars mission that | would've changed everything if it'd succeeded? | vagrantJin wrote: | Sick! | | Will this rover make contact with its forebears at some | point? | krysp wrote: | Awesome achievement! What was the part of the mission you | were most concerned about / most likely to go wrong? | michaelt wrote: | Awesome stuff. | | I couldn't help but wonder, while I watched the feed: What | are the people in mission control doing during the landing? | | Obviously they're monitoring telemetry - but what else? | Presumably the time delay precludes them triggering anything | critical manually, and making post-launch software changes | would be frowned upon? | helmholtz wrote: | They're all going to get wasted tonight, mate. | throwawaygimp wrote: | thats Mars 'tonight', of course | fetacheese wrote: | I have serious doubts that this actually happened | tristanb wrote: | why? | fetacheese wrote: | why not | chrononaut wrote: | I included this the other day in the previous Perseverance thread | but if you're excited for the Perseverance EDL video hopefully | Doug Ellison's composite video of Curiosity's landing (from a | single camera) can tie folks over in the mean time! | https://www.youtube.com/watch?v=RZioPhfxnSY | dtjohnnyb wrote: | Have we any idea when that video will be released (roughly). | sabujp wrote: | can't wait for the choppah | pjfin123 wrote: | Exciting time to be alive! | Daho0n wrote: | I stopped watching videos like these when they started chanting | like some crazy cult when things went well (USA! USA! USA!). No | wonder we can't just get along. | frabbit wrote: | Certainly took away from the experience for me. Also the | constant clapping was irritating along with the guy going "yes, | yess" towards the end. | | Not enough info, too much "personality" and "team work". Waste | of time watching it really. | Ftuuky wrote: | I'm not american but still enjoyed the landing very much. They | sent a freaking nuclear-powered jeep to the surface of another | planet, they can gloat all they want. | Daho0n wrote: | I'm not saying anything bad about the landing. It was a great | feat. I just find the chanting often done in US videos | disgusting. | sidcool wrote: | Isn't the funding coming from US citizens? And NASA is | American after all. I don't see what could be the problem | here. | jbd28 wrote: | Too bad for you to just be happy for these government | employees then. USA! USA! | rnikander wrote: | I wish they'd put a robot like this on Europa. Something that | could drill into the ice and look for life in the (possible) | ocean underneath. ___________________________________________________________________ (page generated 2021-02-19 23:00 UTC)