[HN Gopher] The Mars Helicopter Is Online and Getting Ready to Fly
___________________________________________________________________
The Mars Helicopter Is Online and Getting Ready to Fly
Author : CapitalistCartr
Score : 331 points
Date : 2021-02-28 16:41 UTC (6 hours ago)
(HTM) web link (www.universetoday.com)
(TXT) w3m dump (www.universetoday.com)
| deanclatworthy wrote:
| The headline implies it will be soon, but the article doesn't
| give any information on when the first flight + footage is
| planned to happen.
|
| Tomorrow, days, weeks?
| vidanay wrote:
| The recent NOVA episode indicated that it would be around a
| month after landing for the helicopter flights.
| tesseract wrote:
| I haven't seen anything on specific timing but I read they will
| be looking suitable terrain (flat with no large dangerous
| rocks, but enough small rocks for the helicopter's vision
| system to register) to fly in as the rover drives. There's also
| no provision for the rover to pick the helicopter back up as
| far as I know, so they will be stuck in the same place during
| the 30 day test campaign. Given that and given the "proof of
| concept" nature of the helicopter I imagine there might be a
| desire to start getting data back from the rover's main
| scientific instruments before deploying the helicopter.
| momothereal wrote:
| According to https://www.jpl.nasa.gov/news/how-nasas-mars-
| helicopter-will... (July 2020), it'll launch 60-70 sols after
| landing, so roughly mid-April.
| rwmj wrote:
| Wikipedia page about the Ingenuity helicopter:
| https://en.wikipedia.org/wiki/Ingenuity_(helicopter)
|
| I didn't realise it was so large (1.8 kg, 1.2 m diameter rotors).
| I suppose it has to have the large rotors to be able to generate
| lift in the thin atmosphere, 1/160th of the density [edit:
| pressure, not density - thanks Robotbeat] of the earth's
| atmosphere at sea level according to the article.
| Robotbeat wrote:
| Turns out it's not quite so bad. 1/160th the pressure doesn't
| mean 1/160th density because CO2 is denser for the same
| pressure, especially Martian temperatures. And Jezero crater is
| _much_ lower than Mars "sea level."
| azernik wrote:
| This apparently also introduces some serious control issues -
| with propellers that long and massive, there's substantial lag
| between control inputs and flight changes. In ground tests in
| pressure chambers, it was difficult-to-impossible to manually
| pilot the thing, and even under computer control it's very
| clearly shakier than Earth-atmosphere drones.
| emteycz wrote:
| Wow, I never realized it might be 160 times harder to get off
| the ground on Mars. Perhaps lower gravity helps on the other
| hand, though the difference definitely seems way lower (please
| correct me if my physics is wrong).
| azernik wrote:
| Yup - lower gravity helps, but by much less than the orders
| of magnitude by which the thin atmosphere hinders.
| johnchristopher wrote:
| Will there be a live feed ?
| lr1970 wrote:
| I hope that the chopper will not generate an opaque cloud of dust
| while hovering and am looking forward to seeing spectacular
| images.
| pureliquidhw wrote:
| Given the weight of the craft and thin atmosphere, I would be
| surprised if there was any noticeable surface disturbance
| anytime outside of takeoff/landing.
| thehappypm wrote:
| Wouldn't a thin atmosphere cause more disturbance? Naively,
| something thick and soupy is easier to push around than
| something thick and heavy.
| arrosenberg wrote:
| Atmosphere is required to carry the energy that would cause
| disturbance. With no atmosphere, there are few molecules in
| the space around the copter to transfer the energy to the
| surface.
| NotChina wrote:
| Now to see if X-plane's Mars simulator proves accurate.
| layoutIfNeeded wrote:
| >One of the most significant obstacles for landing on Mars will
| continue to present problems for our heroic helicopter now that
| it is safely on the surface. The atmospheric pressure on the
| surface of Mars is only about 1% that of Earth. To put that in
| perspective, the summit of Mount Everest has only one-third the
| atmospheric pressure of sea level. While this is thought to be at
| (or sadly in some cases beyond) the limit of what humans can
| survive, it is well beyond Earthbound helicopters' range. If
| you've ever wondered why wealthy explorer-types don't just cheat
| and take a helicopter to the summit of Everest, that's why!
|
| Ummm... actually:
|
| >On June 21, 1972, Jean Boulet of France piloted an Aerospatiale
| SA 315B Lama helicopter to an absolute altitude record of 40,814
| feet (12,440 m).[60] At that extreme altitude, the engine flamed
| out and Boulet had to land the helicopter by breaking another
| record: the longest successful autorotation in history.[61] The
| helicopter was stripped of all unnecessary equipment prior to the
| flight to minimize weight, and the pilot breathed supplemental
| oxygen.
|
| >The record was broken on March 23, 2002 by Fred North. North
| achieved an altitude of 42,500 feet (12,954 m) in a Eurocopter
| AS350 B2.
|
| https://en.wikipedia.org/wiki/Flight_altitude_record
|
| Also: Mount Everest AS350 B3 landing -
| https://www.youtube.com/watch?v=WXNXSvnCtKA
| mrbonner wrote:
| Watching the PBS NOVA series "Finding life on Mars" I am so proud
| to see such an astounding diversity of ethnicities involved in
| the Mars 2020 projects. I can't phantom any other countries would
| have inclusively included other ethnicities in such a high
| profile project. Despite so many set backs in 2020, the US is
| still the most inclusive country at least in science and
| research.
| holoduke wrote:
| Have you been at the ESA stations in Europe. Lots of diversity
| there. Even in Russia you have loads of foreigners working.
| About China I am not so sure though
| Kye wrote:
| Ethnicity isn't always visible. Just because a crowd of, for
| example, Indians or Qatari look the same to you in a command
| center video doesn't mean they're all alike or that the whole
| range of identities on the program are in that room at that
| time.
| ris wrote:
| > Despite so many set backs in 2020, the US is still the most
| inclusive country at least in science and research.
|
| What makes you say that and what other countries are you
| comparing it with/do you have information for?
| christiansakai wrote:
| I really really don't understand the point of doing Mars when we
| have a lot of things to do on this Earth.
| idiotsecant wrote:
| I don't understand the point of all this business of learning
| trigonometry when there's all these history books to read!
|
| Relax, we can and should do both. In fact, the various space
| programs have been immensely useful in terms of the technology
| we can apply right here at home _and_ we learn stuff about our
| neighborhood. The more big, bold science and engineering we do
| the more our species benefits.
| neatze wrote:
| Since Perseverance has microphone, I wonder, will we be able to
| hear Ingenuity fly ?
| azernik wrote:
| Very likely. In ground testing, even in a thin Mars-equivalent
| atmosphere, that thing is LOUD.
| Teknoman117 wrote:
| Is the plan to hide Perseverance behind a hill or something in
| the event the flight becomes uncontrolled? Last thing they need
| is a flying blender slamming into it...
| Brajeshwar wrote:
| You should watch Dr. Derek Muller of Veritasium, who did a video
| (2019) details of the Helicopter while it was being built.
|
| https://www.youtube.com/watch?v=GhsZUZmJvaM
| darknavi wrote:
| Something really cool about seeing the device sitting on a
| table and realizing that it is now on Mars.
|
| Working on this stuff must be _very_ rewarding (assuming that
| the payloads land in one piece!).
| [deleted]
| TaupeRanger wrote:
| Six days old. Are there any recent updates? Didn't see much on
| the official Twitter or website.
| Youden wrote:
| Does anyone know why they chose to send a helicopter and not some
| kind of plane or glider?
|
| I would've thought that a fixed-wing aircraft would have been
| simpler, lighter, faster and more efficient.
| Robotbeat wrote:
| How would it take-off and land without runways?
|
| VTOL flying wing designs have been proposed. But the first step
| is demonstrating any powered flight at all, which means
| helicopter.
| NikolaeVarius wrote:
| How many runways do you see on Mars
| zokier wrote:
| UAVs on Earth commonly launch on catapults and not runways.
| BurningFrog wrote:
| OK, but landing it back on the catapult seems very hard.
| EarthLaunch wrote:
| What if a glider separated prior to the initial main landing?
| I guess that would increase the risks around the landing.
| NikolaeVarius wrote:
| I mean the point is to test a re-flyable vehicle. A single
| use glider would seem to defeat the point
| ilamont wrote:
| _One of the most significant obstacles for landing on Mars will
| continue to present problems for our heroic helicopter now that
| it is safely on the surface. The atmospheric pressure on the
| surface of Mars is only about 1% that of Earth._
|
| Does this also limit the use of parachutes on Mars, or require
| bigger canopies? I know that Perseverance had a parachute for
| part of the descent, but not the final landing sequence. IIRC one
| of the earlier probes was designed to bounce rather than gently
| floating down.
| bryananderson wrote:
| Yes indeed. Mars entry, descent, and landing (EDL) is hard. On
| Earth it's easy: we can use the thick atmosphere to decelerate
| to a gentle drop into the ocean. On the Moon it's easy: the
| minimal gravity makes powered descent feasible. On Mars it's
| hard: too much gravity for an easy powered descent, too little
| atmosphere for an easy aerobraked descent. Larger spacecraft
| such as Curiosity and Perseverance (sky crane) and Spirit and
| Opportunity (bouncing air bags) have to get creative.
| ilamont wrote:
| Thanks for your reply. I never thought a NASA engineer would
| answer me, but one of the things that blows me away about
| this community is truly knowledgeable people are participants
| in discussions and often weigh in.
| dogma1138 wrote:
| Both, but the main limit of a parachute is that our probes
| don't go into orbit first but rather crash on Mars.
|
| So you enter the atmosphere at higher than orbital speeds. From
| orbit a parachute might be doable despite the relatively thin
| atmosphere.
|
| Stationary probes can use retro rockets to land because you
| don't care about their stationary mass that much.
|
| For rovers it's more tricky so you have to either use airbags
| like the smaller rovers did or a propulsive landing like
| Percy/Curiosity.
|
| The sky crane was chosen as the method for those because they
| are too massive to do a cushioned crash landing and they won't
| be likely able to move with the weight of the propulsive
| landing system so we have to ditch it.
|
| The sky crane is basically the worlds most expensive bungee
| jump.
|
| The rockets on the sky crane bring the rover to hover and then
| it drops to the ground on a set of arresting cables.
| NortySpock wrote:
| Mars atmosphere is sometimes characterized as "enough so that
| you have to deal with it, but not enough to finish the job
| [with parachutes]"
|
| I expect NASA just builds the biggest single parachute they
| think they can safely use, and then works downstream of that on
| a landing system.
|
| Spirit and Opportunity used heatshield+parachute+rockets +
| bouncy airbags.
|
| https://en.wikipedia.org/wiki/Mars_Exploration_Rover
| Daniel_sk wrote:
| Yes it does. The parachutes are unable to slow down the probes
| to a soft landing - they would have to be extremely large,
| which would make it even more heavy for landing. The large
| parachute on Perseverance slowed down the entry module to about
| 200 mph (321 km/h) which is not enough. Perseverance has a
| weight of 2,260 lbs (1,025 kilograms). The Mars Exploration
| Rover (Spirit) used parachute + retrorockets + inflatable
| airbags, but it weights only 408 lb (185 kilograms).
| jefft255 wrote:
| I am incredibly excited for this. Can believe how nervous the
| control engineers must be for this. Not sure what quality of the
| footage to expect from this.
| disago wrote:
| Sadly, this helicopter won't record any footage, it is only
| meant to test flight control and to proof that the idea will
| work for future missions. There is a interesting Veritasium
| episode (youtube) that talks about this (interviewing the
| actual designer from the JPL). The only footage will be from
| Perseverance filming the flight.
| l2p wrote:
| This is not correct, there are multiple downward facing
| cameras [a]:
|
| 1) Navigation (NAV) Camera. This is a global-shutter, nadir
| pointed grayscale 640 by 480 pixel sensor (Omnivision OV7251)
| mounted to a Sunny optics module. It has a field-of-view
| (FOV) of 133 deg (horizontal) by 100 deg (vertical) with an
| average Instantaneous Field-of-view (IFOV) of 3.6 mRad/pixel,
| and is capable of acquiring images at 10 frames/sec. Visual
| features are extracted from the images and tracked from frame
| to frame to provide a velocity estimate.
|
| 2) Return-to-Earth (RTE) Camera. This is a rolling shutter,
| high-resolution 4208 by 3120 pixel sensor (Sony IMX 214) with
| a Bayer color filter array mated with an O-film optics
| module. This camera has a FOV of 47 deg (horizontal) by 47
| deg (vertical) with an average IFOV of 0.26 mRad/pixel.
|
| [a]https://trs.jpl.nasa.gov/bitstream/handle/2014/46229/CL%23
| 17...
| hcrisp wrote:
| Shouldn't that be a Return-to-Mars (RTM) Camera?
| _Microft wrote:
| No, it is going to record images meant to be returned to
| Earth. See section "Sensors" on page 13 in
|
| https://trs.jpl.nasa.gov/bitstream/handle/2014/46229/CL%2
| 317...
| disago wrote:
| But aren't those cameras just for navigation and won't
| record or stream any footage?
|
| Edit: spelling
| tjoff wrote:
| One of the stated goals is to use of the drone to scout
| interesting places for other drones. In theory I guess it
| could take that decision without sharing the source
| images, but that seems a bit far fetched. You'd want to
| study them in ridiculous detail.
| orev wrote:
| Wow, that's disappointing. I'm surprised they couldn't
| squeeze a basic mobile phone camera module on there just for
| the sake of it.
| nitrogen wrote:
| I had initially assumed that they would be using it for
| aerial photos to improve navigation decisions. Kind of sad
| if not.
| jefft255 wrote:
| There absolutely are cameras on board, and yes they are
| used for navigation.
|
| My original question relates more to bandwidth, storage
| and processing limitation which may mean that we won't
| see high quality 30 FPS video.
| giantrobot wrote:
| The Snapdragon CPU has plenty of power for JPEG encoding
| and likely even hardware accelerated encoders. The
| 640x480 8bpp navcam images could be entirely usable at a
| fairly lossy 40:1 compression ratio which ends up about
| about 8KB per frame, for a 90s flight recording at 10fps
| that's only about 7.2MB to record the whole flight. It
| would take a little under 5 minutes to send that back to
| the rover at 200kbps. The color high resolution camera
| isn't set up for high frame rate recording IIRC so that
| was never an option.
|
| High quality 30fps video was never really an option but
| it's entirely possible/likely to get navcam video after a
| flight. The Snapdragon is also fast enough to do
| intraframe compression codec (even h.264) for the navcam
| video to be able to stream it live back to the rover for
| relaying back to Earth later like was done with the
| landing imagery.
|
| The nature of Perseverance relaying through orbiters for
| high speed uplink to Earth was always going to preclude
| "live" video from any instrument. The only data important
| enough for "live" transmission is vehicle telemetry and
| even then that's only available for the portion of a sol
| (Martian sidereal day) that Earth is visible from the
| rover.
| umeshunni wrote:
| I suspect it's to save power. Even mobile phone cameras are
| very power hungry.
| kerng wrote:
| I think the rover is at least going to film the flight, but
| agree a camera in it would have been dope.
| akiselev wrote:
| The problem isn't the camera, it's the uplink to
| Perseverance and all the other parts required for a usable
| camera. They're using Zigbee [1] to communicate with the
| Rover at 200 _kbps_ and the solar panel recharging the
| batteries also have to power heaters to keep the
| electronics alive - there 's no hardware connection between
| the two for data or power exchange AFAICT. The drone is
| already so heavy that it can only stay aloft for 90 seconds
| to a few minutes between charges so between the extra
| battery, lens, better antenna and RF module, etc. it'd
| require a redesign of the entire mission.
|
| [1] https://rotorcraft.arc.nasa.gov/Publications/files/Bala
| ram_A... - page 15
| _joel wrote:
| It's not that heavy, relatively speaking, it has to spin
| the rotors a _lot_ faster to gain altitude in 1%
| atmosphere of Earth, hence the shorter flight time.
| [deleted]
| mholt wrote:
| Are you suuuuure about that?
|
| > Its payload is a high resolution downward-looking camera
| for navigation, landing, and science surveying of the
| terrain, and a communication system to relay data to the
| Perseverance rover.
|
| (From Wikipedia)
|
| Also: https://mars.nasa.gov/resources/25526/bottom-of-
| ingenuity-ma...
|
| I'm pretty sure the point of the helicopter, other than to
| test powered flight, is to capture frames.
| bichonnages wrote:
| It does have cameras.
|
| https://mars.nasa.gov/resources/25526/bottom-of-ingenuity-
| ma...
| birktj wrote:
| One of the things I find really cool about Ingenuity is how it is
| in large based on consumer hardware. The main processor is a
| Snapdragon 801 running Linux which communicates with Perseverance
| using the Zigbee protocol [1]. Perseverance on the other hand
| uses a RAD750 from 2001! If successful I hope this can lead to
| more modern hardware for these kinds of missions in general.
|
| [1] https://en.wikipedia.org/wiki/Ingenuity_(helicopter)
| samstave wrote:
| If you were to build the exact same helicopter here based on
| those parts what would be the cost vs what's the device on Mars
| cost? Also, I know plenty of solid engineers who I could build
| one thing based on that, obviously not taking atmosphere and
| G-forces into account to get there.
|
| Also Linus finally got his progeny to Mars. That's a pretty
| cool accomplishment:
|
| "What have you built?"
|
| Well, I invented one of the most prolific operating systems the
| world has ever seen, but not just this world - there is a
| helicopter on Mars that is flying due to the seeds which I
| planted that day..."
|
| What have you built?
| kingo55 wrote:
| It's not just atmosphere and g-forces. The cold temperatures
| mean the helicopter spends 2/3 of its battery power keeping
| the batteries and electronics from freezing.
|
| Good rundown of how it was built:
| https://www.youtube.com/watch?v=GhsZUZmJvaM
| mushufasa wrote:
| One of the fascinating things about space silicon is that NASA
| spends many years hardening specific processors to withstand
| the types of shocks and electromagnetic interference from space
| travel. These intensive processes mean that the equipment they
| can use is always 10-20 years behind the modern equivalents.
| emkoemko wrote:
| and yet they are fine with using a snapdragon arm processor
| on the helicopter?
| mhh__ wrote:
| The helicopter is both only rated for a certain mission and
| potentially liable to smash straight into the ground.
|
| On top of that, I'm sure JPL would love to move with the
| times, which is why the helicopter _is_ using the more
| modern processor.
| syoc wrote:
| > Ingenuity runs Linux (for the first time on Mars) and
| uses the open-source F' software framework on a 2.26 GHz
| quad-core Snapdragon 801 processor. Radiation hardened
| processors aren't fast enough for the real-time vision
| requirements of the experiment--but as an unprotected COTS
| processor, it will fail periodically due to radiation-
| induced bit flips, possibly as much as every few minutes.
| NASA's solution is to use a radiation-tolerant FPGA
| ProASIC3 to keep an eye on the CPU (paper) and software
| that attempts to double-check operations as much as
| possible. "[I]f any difference is detected they simply
| reboot. Ingenuity will start to fall out of the sky, but it
| can go through a full reboot and come back online in a few
| hundred milliseconds to continue flying."
|
| Source: https://orbitalindex.com/archive/2021-02-24-Issue-1
| 05/#ingen...
| marcinzm wrote:
| Aren't smaller transistor sizes also more susceptible to
| radiation issues which means you can't really use newer
| processors without ever more effort in radiation hardening?
| Robotbeat wrote:
| Smaller transistors also have a smaller cross-section so
| for the same number of transistors this somewhat cancels
| out.
| eecc wrote:
| But then you have to build for redundancy rather than
| just performance (say, sacrifice some floor-plan to error
| correction, recovery, circuit duplication, etc...)
| Robotbeat wrote:
| Still a game of probability either way.
| fuzzy2 wrote:
| The CPU will probably be destroyed by radiation before long.
| I'd guess the key factors here were weight, power draw, size
| and perhaps performance. A radiation-hardened CPU probably
| didn't fit the bill. It's also super expensive.
| lnsru wrote:
| Any individual part is peanuts compared to overall mission
| cost. Anyway, it's a great PR stunt for QCOM. It's not that
| big secret, that cubesats successfully use automotive grade
| off shelf parts.
| lights0123 wrote:
| > perhaps performance
|
| absolutely performance. Yes to the other three for sure, but
| the engineers reported that there was no way they were
| running flight control using image tracking on a 200MHz CPU.
| tal8d wrote:
| Not in python, maybe. Smartbombs have been doing the
| necessary image processing with much less processing power,
| on much less capable sensors, for a long time.
| NikolaeVarius wrote:
| What. I dont understand how you can make this claim.
| Guided bombs are NOT using CV with optical cameras. They
| use lasers, GPS, and other non "fancy" techniques.
|
| I just don't get in what world you think military
| munitions are using CV for targeting bombs.
| marcinzm wrote:
| As the name RAD750 indicates, that processor is designed to be
| radiation hardened which matters for longer missions. I doubt
| the Snapdragon 801 will survive as long or have as few errors
| but it also doesn't matter since Ingenuity isn't aimed for long
| term usage.
| m463 wrote:
| One thing that's not clear to me is what the radiation is
| like on mars. Mars has an atmosphere, but no magnetic field.
|
| Is it like the situation high in earth's atmosphere (like
| using your ipad on a commercial flight), or would it be more
| like on the moon with no protection?
| madaxe_again wrote:
| Between the two. 30 uSv per hour on the surface of Mars on
| average compared to 60 uSv on the Moon - compared to 5 uSv
| on a jet. Not friendly, but not too awful.
| dmurray wrote:
| Or 0.5 per hour on Earth at sea level. That's only 2
| orders of magnitude difference. Given that we don't
| expect radiation damage to be a major source of failures
| in Earthbound consumer or commercial electronics, it's a
| bit surprising it's such a big deal in space.
| emkoemko wrote:
| yes but these chips having to function and survive on the
| way to the planet right? and they do all sorts of
| software updates etc during this time. Maybe we could
| shield them and that would be fine? or would that add to
| much extra weight
| nradov wrote:
| There are actually a lot of bit flips in Earthbound
| electronics due to lack of parity error checking. But
| those bit flips don't necessarily cause failures, or when
| they do it's impossible to determine the root cause.
| azernik wrote:
| The composition of that radiation is important - Earth's
| atmosphere preferentially filters out a lot of the
| higher-energy particles that are likely to permanently
| damage electronics. The sievert as a unit is weighted
| based on damage to biological systems, not electronics.
| contravariant wrote:
| Well 2 orders of magnitude can turn a problem that occurs
| once a decade into a problem that occurs once a month so
| it's not too surprising that the problem is a bigger deal
| in space.
| birktj wrote:
| What I imagine for long lived and high-cost missions is using
| some sort of co-processor setup with a radiation hardened
| processor and a faster and more modern processor. These
| rovers run a lot of computer vision algorithms and I believe
| more powerful hardware would be quite useful. They may
| already do something like this, however my understanding is
| that there is a lot of skepticism in integrating these less
| fault-tolerant processors. Ingenuity could help remove some
| of the skepticism and lead to more systems like this in the
| future.
| alexvoda wrote:
| I wonder if it wouldn't have been possible to do this on
| Perseverance too. After Ingenuitys mission is done they
| could have lugged it arround for extra processing power for
| as long as it survives. I doubt the extra weight causes
| that much extra energy consumption.
|
| The software stack is probably not ready for that since the
| plan is to abandon it after its mission. And the Zigbee
| protocol is rather limmited.
| Robotbeat wrote:
| It's less about longevity and more about reducing errors.
| Interestingly, Ingenuity has some sort of watchdog that can
| reset the Snapdragon _in-flight_ fast enough to recover if
| there _is_ an error.
| EarthLaunch wrote:
| Reminds me of SpaceX or Erlang; build a process that
| handles errors rather than an error free process.
| NikolaeVarius wrote:
| I mean its space. Any computer expected to be in space
| and do non completely trivial things have tons of
| mechanisms in place to survive computer issues.
| ddingus wrote:
| Presumably. That is all part of this test.
| jjoonathan wrote:
| Reminds me of Apollo 11, where the computer kept resetting
| on the way down to the lunar surface but still got Neil
| Armstrong and Buzz Aldrin to the moon with the whole world
| watching.
| kabdib wrote:
| It wasn't resetting, it was ditching lower priority tasks
| that it didn't have (real) time to accomplish. Notably,
| the computer was still doing important work (ahem, flying
| the LM :-) ), and the tasks it didn't have time to do
| were not critical.
|
| The team had recently seen similar failures in
| simulation, and was able to quickly decide it was okay to
| proceed.
| jhayward wrote:
| > Notably, the computer was still doing important work
| (ahem, flying the LM :-) ), and the tasks it didn't have
| time to do were not critical.
|
| I believe this is incorrect. From an earlier HN
| discussion:
|
| " _The 1202s were also a lot less benign than is often
| reported. They occurred because of the fixed two-second
| guidance cycle in the landing software. That is, once
| every two seconds, a job called the SERVICER would start.
| SERVICER had many tasks during the landing. In order:
| navigation, guidance, commanding throttle, commanding
| attitude, and updating displays. With an excessive load
| as caused by the CDU, new SERVICERs were starting before
| old ones could finish. Eventually there would be two many
| old SERVICERs hanging around, and when the time came to
| start a new one, there would be no slots for new jobs
| available. When this happened, the EXECUTIVE (job
| scheduler) would issue a 1201 or 1202 alarm and cause a
| soft restart of the computer. Every job and task was
| flushed, and the computer started up fresh, resuming from
| its last checkpoint. It was essentially a full-on crash
| and restart, rather than a graceful cancellation of a few
| jobs. And unlike is often said, the computer wasn 't
| dropping low-priority things; it was failing to complete
| the most critical job of the landing, the SERVICER._
|
| _Luckily, the load was light enough that of the SERVICER
| 's duties, the old SERVICER was usually in the final
| display updating code when it got preempted by a new
| SERVICER. This caused times in the descent when the
| display stopped updating entirely, but the flight
| proceeded mostly as usual. However, with slightly more
| load, it was fully possible that the SERVICER could have
| been preempted in the attitude control portion of the
| code, or worse yet, the throttle control portion. Since
| each SERVICER shared the same memory location as the last
| one (since there was only ever supposed to be one running
| at a time), this could lead to violent attitude or
| throttle excursions, which would have certainly called
| for an abort. Luckily, this didn't happen -- and the
| flight controllers didn't abort the mission not because
| 1202s were always safe, but because they didn't
| understand just how bad it could be, were the load just a
| tiny bit higher._"
|
| [1] https://news.ycombinator.com/item?id=20791307
| ericbarrett wrote:
| A consumer chip is a lot more likely to be permanently
| damaged by a "silver bullet" cosmic ray, though. Rad-hard
| chips don't just have shielding, they can also have
| redundant circuits and modifications to the foundry
| process. That said, I'm sure Ingenuity's processor is fit
| to purpose.
| alexvoda wrote:
| It's a bit of a shame that radiation hardened chips are
| stuck so far in the past.
|
| I believe the volume is so low it does not warrant the
| investment to make radiation hardened versions more
| often.
| simonh wrote:
| Actually being stuck in the past might be a feature.
| Denser circuitry is likely to be more vulnerable to
| interference by ionising radiation and more vulnerable to
| physical damage from high energy particles.
| inamberclad wrote:
| Yes, there's a flight qualified microsemi FPGA (a ProASIC,
| I think) that acts as a supervisor for the vehicle.
| samfisher83 wrote:
| In general the older nodes work better for radiation and other
| cosmic forces.
|
| https://en.m.wikipedia.org/wiki/Radiation_hardening
|
| That's why they don't use the latest and greatest in the space.
| MereInterest wrote:
| Non-mobile link:
| https://en.wikipedia.org/wiki/Radiation_hardening
| JKCalhoun wrote:
| Can't all of the radiation issues be mitigated with proper
| shielding of the electronics?
| Teever wrote:
| It's trickier than it seems because some forms of radiation
| can induce different kinds of radiation when they hit the
| dense shielding so you're kind of back to square one in
| that you still need a radiation resistant processor.
| lisper wrote:
| Yes, but the problem is that radiation shielding is heavy
| because it's typically made of lead.
| Robotbeat wrote:
| They work better primarily because they had previously
| invested in the tooling to rad-harden them and it's really
| expensive to do that again one time for each mission; cheaper
| to rely on already-rad-hardened designs.
| jessriedel wrote:
| Doesn't radiation mostly cause random one-off errors rather
| than permanent defects? If so, then if the rad-harden stuff
| is 100x slower (which I think is approximately right?), it
| is almost certainly better to use error correction on non-
| rad-hardened hardware.
| ejolto wrote:
| In addition to SEUs (single event upsets) which are bit
| flips, there are also the following Single Event Effects
| (See) that are destructive:
|
| - Single Event Burnout, SEB
|
| - Single Event Gate Rupture, SEGR
|
| - Single Event Latch-up, SEL these can be recoverable
|
| In addition there are also Total Ionizing Dose (TID)
| Effects https://radhome.gsfc.nasa.gov/radhome/tid.htm
| londons_explore wrote:
| Many types of bit error are not recoverable without a
| full system reset. It isn't a matter of a simple "this
| bit in ram got corrupted", but more "this floating point
| unit has got into a state where it will not produce a
| result, and will therefore hang the entire processor".
|
| Therefore boot time becomes critical - if you end up
| rebooting due to bit errors multiple times per second,
| you can't afford to wait for Linux to start up each
| time...
| ajuc wrote:
| Run 9 systems in parallel and reset the ones that give
| less common results or no results at all.
|
| You still have 10% the surface area, power usage and
| weight and 10 times the speed of the radiation hardened
| ones.
| spockz wrote:
| Well I suppose they do not have to load all the kernels
| and drivers that Linux provides today.
|
| I wonder how one could use micro kernels to further
| improve startup time and have a mini distributed
| OS/kernel for each component.
| dawnerd wrote:
| And that's why it's wise to have multiple systems running
| at the same time, if one errors you still hopefully have
| another online. There's a reason airplanes and now cars
| are designed this way. I'm sure they're working towards
| this too.
| MayeulC wrote:
| Not necessarily; physical size matters a lot.
|
| Just an example: consider you were to add some extra
| electrical charge to the gate of a transistor (from an
| electron or ion beam, I don't know).
|
| A larger transistor has a higher gate capacitance, it is
| therefore quite immune against a few extra charges. On
| smaller transistors, though, it could dramatically increase
| the voltage, leading to a bit error, or destroying the
| transistor. Capacitance in this case is proportional to the
| area.
|
| Higher density also has some inherent drawbacks against
| particles, since a damaged part is proportionately more
| damaged if it is smaller.
|
| More ancient processes are also higher-voltage, and higher-
| current, so they can handle a lot more noise on these
| signals.
| Asraelite wrote:
| This raises the question, why not simply continue to make
| larger circuits today for this purpose?
|
| Surely we could still make a chip today with the same
| transistor size as one from 2001, but better in other
| ways.
| alexvoda wrote:
| I believe the reason is that volume is too low. The
| radiation hardened chips for Curiosity and Perseverance
| are variants of Power chips made by BAE. I am surprised
| though that they have not released any newer chip in time
| for Percy. There is a newer generation, the 5500, but I
| believe it was not ready for Percy. Percy uses the same
| chip as Curio.
| 7800 wrote:
| While the chip/circuit design itself matters, it's good to
| note that NASA will run several pieces of the same/similar
| hardware for fault tolerance in a component[1] as well as
| attempting to protect it. This isn't bad, but I also think
| that design of the chips and circuits should come into play
| if it's proven in testing to be affected by radiation, e.g.
| don't use an RPi2 in a Xenon Flash testing lab.
|
| [1]- https://science.nasa.gov/science-news/science-at-
| nasa/2005/1...
| darknavi wrote:
| > communicates with Perseverance using the Zigbee protocol
|
| I hope they installed the Home Assistant Core docker container
| on Perseverance. Gotta get those sweet dashboards.
| raverbashing wrote:
| It seems other parts are more modern. Yes, the main processor
| is a RAD750, but the peripherals can use modern components and
| there's some USB and Ethernet here and there (like the cable
| between the sky crane and the rover)
|
| Reliability is very important and space is harsh. I assume on
| the surface the radiation levels are low enough for Earth
| systems to work (maybe playing a bit with voltage/clock
| frequency helps, not sure how much shielding they can add,
| probably not too much).
| dehrmann wrote:
| It's nice that NASA isn't falling victim to not-invented-here.
| If a commodity part or protocol can do the job, no sense
| reimplementing it.
| tomerico wrote:
| The problem is that NASA is designed around long term and
| expensive projects. At one point, a fast iterating company like
| space-x will surpass their achievements.
| mhh__ wrote:
| Why would SpaceX bother doing science, though? If you imagine
| a project like Voyager, you might think they just dump the
| data and "go home" (not quite, obviously) but to analyse the
| data and to know what to look for they had to hire geologists
| and meteorologists (for example) along with the planetary
| scientists and co.
|
| NASA _should_ be about long term and expensive projects,
| SpaceX is just a tool to achieve that goal which is to do new
| science regardless of whether it is in the air or in space.
| newsbinator wrote:
| SpaceX will do any science that's profitable in the
| near/mid term
| alexvoda wrote:
| Musk will do everything to achieve his dream of
| colonising Mars.
| ayoubElk wrote:
| Just thinking about the amount of work done planning, creating,
| and deploying this blows my mind!
|
| Incredible achievement!
| laydn wrote:
| Why is nobody worried about the helicopter crashing to the rover
| and possibly destroying a science instrument? How far will the
| helicopter be from the rover?
| [deleted]
| holoduke wrote:
| Of course they worried. That's why the first flight will just
| be a accent of 3 meters.
| ncallaway wrote:
| I would imagine that NASA is _extremely_ worried about that,
| and has gone to great lengths to ensure it 's not an outcome.
|
| Why do you assume that nobody has worried about this, or
| considered this contingency?
| upbeat_general wrote:
| I'm pretty sure this was one of the main criteria for building
| the helicopter since the -reject is not essential to the
| mission but is instead is a demonstration.
|
| It's probably also why they're waiting to fly it so that the
| rover is a bit further away
| dev_tty01 wrote:
| No it is still attached to the rover.
| shawnz wrote:
| The helicopter is itself also a science instrument. How do they
| prevent any of the instruments from destroying each other?
| Careful planning, I would guess
| NikolaeVarius wrote:
| Because NASA isn't full of idiots.
| julienchastang wrote:
| Fun fact: This is not the first time a space program has flown on
| another planet. The Soviets launched weather balloons on Venus
| during the Venera missions [1]
|
| [1] https://en.wikipedia.org/wiki/Vega_program#Balloon
| TedShiller wrote:
| A balloon is barely an aircraft
| [deleted]
| tachyonbeam wrote:
| A solar drone that takes hours to charge and flies only a
| minute at a time is barely an aircraft too. Don't get me
| wrong, it's a very cool tech demo and I can't wait to see the
| video, but IMO if your goal is to take pressure/composition
| measurements in the atmosphere at a variety of altitudes, a
| weather balloon is the right tool for the job.
| endymi0n wrote:
| This is so cool, I didn't know about these yet and I'd call
| myself a space buff...
|
| Speaking of flight and picking the nits here -- looks like
| Wikipedia also isn't completely correct here:
|
| > It is planned to make the first powered flight on any planet
| beyond Earth
|
| ...arguably the first _powered_ flights were done by the sky
| cranes of Opportunity and Perseverance
| svachalek wrote:
| It seems that rocket propulsion does not count as "powered
| flight"
| alpaca128 wrote:
| > ...arguably the first _powered_ flights were done by the
| sky cranes of Opportunity and Perseverance
|
| Not the Apollo 11 lunar module? In contrast to the sky cranes
| it actually lifted off again.
| dal wrote:
| The moon is not a planet.
| rriepe wrote:
| I'd argue Mars is still the most impressive. Rockets in
| no atmosphere is easy. Floating on Venus is easy because
| it has more atmo than any other rocky planet.
|
| Figuring out something that works well in Mars' thin (but
| still there) atmosphere, especially a _helicopter_ , is
| really impressive. The celestial body classification is
| just a cherry on top.
| dotancohen wrote:
| By many definitions the Earth-Moon system is a dual
| planetary system. The moon has more that 1% the mass of
| the Earth, which is by far the largest primary-secondary
| "not a planet" system in the solar system. Only not-a-
| planet Pluto and Charon exceed it.
|
| Also, Isaac Asimov considered the system a dual-planet
| system as the Moon's path around the sun is at no point
| convex nor retrograde.
| m4rtink wrote:
| On the Moon the first controlled powered flights were
| likely the Surveyor and Luna probes - they had braking and
| landing thrusters controlled by onboard avionics.
| m4rtink wrote:
| On Mars the Viking probes used rockets for controlled
| landing, so that likely also counts. Pathfinder just had
| one shot braking rockets.
| taf2 wrote:
| For sure the soviets did some neat science work but I think a
| motorized helicopters flying on Mars is pretty darn cool too
| compared to a ballon floating in a dense atmosphere it even
| feels like an advancement
| tachyonbeam wrote:
| They're both cool because they're both technological firsts.
| The weather balloon on Venus was in 1985, a whole 35 years
| ago!
|
| https://www.nytimes.com/1985/06/12/us/soviet-drops-
| weather-b...
| tus89 wrote:
| If we understand "flight" as being the use of a wing to
| generate lift in an atmosphere, then I think we can safely say
| this is the first time we have flown on another planet. I
| assume this little helicopter actually has rotary wings rather
| than fans.
| contravariant wrote:
| If we're splitting hairs then the lack of control seems like
| a better criterion to distinguish the two. If you ask me
| there's no reason a zeppelin would be inherently less
| 'flighty' than a helicopter.
| tus89 wrote:
| I think they are more "floaty" that "flighty" :P
| rhino369 wrote:
| The common understanding of flight definitely doesn't include
| lighter than air (well atmosphere in this case) vehicles.
|
| The first flight was in 1903, not 300 BC China when they used
| sky lanterns.
| monkeydreams wrote:
| > The first flight was in 1903
|
| The first powered flight was in 1903, with the criteria
| that it was not gravity assisted, that it was sustained and
| that it was controlled. No one is claiming that it was the
| first flight ever.
| sangnoir wrote:
| Lighter than air _is_ flight - one cannot say dirigibles
| and hot air balloons are not flying machines.The
| distinction is made between lighter than air and heavier
| than air - for which the first was success was by the
| Wright brothers.
| ChuckMcM wrote:
| And given the density of Venus' atmosphere, here is a fun
| thought experiment.
|
| It may be possible to make 'titanium' balloons for longer term
| operation. The would work by creating the balloon envelope on
| earth, have a sealing mechanism that you activated in orbit so
| they had vacuum inside. And then drop them into the atmosphere.
|
| Same idea a glass floats on fishing nets[1] except with
| titanium (so they can withstand the compression forces given
| they have a vacuum inside). It might be useful/necessary to put
| some additional structure inside the envelope for strength but
| like eggs, the sphere is a pretty good shape for distributing
| compressive force.
|
| Anyway, put a number of them on tethers attached to the
| instrument payload and drop it off into the atmosphere once
| you've gone trans-sonic with parachutes or retro rockets. The
| platform will then fall to the point where the lifting force of
| the floats is equal to the weight of the platform.
|
| Ideally the titanium would be impervious to the atmospherics's
| corrosive effects.
|
| [1]https://en.wikipedia.org/wiki/Glass_float
| dalbasal wrote:
| There's something ironic about sending a spaceship to another
| planet and then being excited about a flying machine's maiden
| journey.
|
| That said, I'm _super_ excited. I hope we get VR video at some
| point. I want to soar over martian hills. These guys are my
| heros.
| poundofshrimp wrote:
| > February 22, 2021
| undefined1 wrote:
| thank you NASA (and SpaceX) for being a source of inspiration and
| hope in a time when it's in such short supply. amazing work!
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