[HN Gopher] An extrasolar world covered in water?
___________________________________________________________________
An extrasolar world covered in water?
Author : Brajeshwar
Score : 134 points
Date : 2022-08-30 15:07 UTC (2 days ago)
(HTM) web link (nouvelles.umontreal.ca)
(TXT) w3m dump (nouvelles.umontreal.ca)
| pleb_nz wrote:
| We should stop talking about it and just go.... I'm busy that day
| though, who wants my place ...
| ianai wrote:
| Is there a better source? "Freethink" seems to be confusingly
| mixing terms.
|
| FWIW, we don't have telescopes to resolve the surface of planets
| like this so they're using inferences to approximate composition
| and extrapolating surface characteristics. Ie by these methods at
| a similar distance the statements are roughly equivalent to what
| we'd say of earth if we were seeing it at this distance. The
| crucial takeaway seems to be it might have a proper water cycle
| with or without surface rock.
|
| Edit-another comment or pointed to
| https://arxiv.org/abs/2208.06333
| ghostpepper wrote:
| https://exoplanets.nasa.gov/news/1710/discovery-alert-intrig...
| perihelions wrote:
| https://arxiv.org/abs/2208.06333
|
| ( _" TOI-1452 b: SPIRou and TESS reveal a super-Earth in a
| temperate orbit transiting an M4 dwarf"_)
| [deleted]
| m3kw9 wrote:
| Knowing that the planet exists and doing its own thing right now,
| exotic weather patterns and all is amazing
| aldanor wrote:
| You mean, existed 100 years ago?
| causi wrote:
| _Based on those observations, the exoplanet appears to be about
| 70% larger than Earth with just five times its mass. That means
| it's less dense than Earth_
|
| Seems like a rather large leap to go from that to "it's a water
| world", at least in these days where we get a "this new exoplanet
| may be covered in water!" headline every few months.
| dougmwne wrote:
| Not necessarily. We understand lots of the underlying orbital
| physics and know from stellar lifecycles how much of each
| element to expect. From there you can run the math on radius
| and density and only be left with so many possibilities of what
| the thing is made of. It's not certainly water, just one of the
| likely possibilities. An interesting hypothesis that could
| actually be tested by atmospheric spectroscopy using Webb.
| winReInstall wrote:
| So its a droplet, were a small moony core tumbles around in the
| crushing depths?
| dougmwne wrote:
| Someone's would have to do the math on the core pressure, but
| likely there would be an ice mantle around a rocky core and
| possibly a supercritical layer.
|
| https://en.m.wikipedia.org/wiki/Phase_diagram#/media/File%3A.
| ..
| LatteLazy wrote:
| 1.7^3= 4.913. So even if 1.7x large just means radius, if it
| has 5x the mass that would still make it MORE dense than earth
| right?
| svachalek wrote:
| I guess that "about" is doing a lot of work here. Like maybe
| it's 1.74^3.
| dang wrote:
| Url changed from https://www.freethink.com/space/ocean-planet,
| which points to this.
| khendron wrote:
| Getting flashbacks to the sci-fi short story "Grenville's
| Planet". First contact may not go very well.
| dvh wrote:
| Are water worlds even possible around flare stars?
| NoGravitas wrote:
| Only 83 days at warp 6.2, the standard cruising speed for an
| Intrepid-class starship (or 7.13 days at warp 9.975, maximum
| sustainable speed for the same ship).
| ben_w wrote:
| I wish the script writers had been more self-consistent.
|
| 100 ly in 7.13 days would've had them home in 13.6 years even
| without shenanigans. (The warp speed graph I saw suggested more
| like 7 years, which is even worse for the fundamental plot
| contrivance of the show).
| thomond wrote:
| How long would it have taken to warp to the Gamma Quadrant
| wormhole I wonder?
| SCAQTony wrote:
| Warp factor 1 is the speed of light. Accelerating safely to the
| speed of light at a constant 1G acceleration would take 354
| days. After that, you would arrive instantaneously no matter
| where or how far since time stops for you once you reach the
| speed of light.
|
| https://setiathome.berkeley.edu/forum_thread.php?id=34381#:~...
| .
| once_inc wrote:
| I might be able to best that, if Skippy would reprogram a
| wormhole in the neighborhood.
| Maultasche wrote:
| That may not work. I think the wormhole controller AIs are
| getting pretty tired of his antics by now.
| wkdneidbwf wrote:
| see you there!
| klyrs wrote:
| This is both exciting and somewhat disappointing. It sounds like
| the water is so deep that it's probably solid ice (due to the
| intense pressure) before you get to a rocky core. Life on earth
| needs nutrients extracted from the rocks. If life formed on this
| planet, any non-buoyant corpse would sink to the bottom and
| disappear forever. That is to say, it would almost certainly die
| out very quickly from lack of nutrition.
| ProjectArcturis wrote:
| You might have tiny pockets of life around undersea volcanic
| vents.
| gus_massa wrote:
| A lot of minerals dissolve in water. Without oxygen in the air
| (like here, before those nasty cyanobacteria released a lot of
| oxygen) you can get also iron salts disolved in the oceans.
| https://en.wikipedia.org/wiki/Great_Oxidation_Event#Geologic...
|
| Also, if there are volcanos, they will create plumes dirty of
| hot water with a lot of disolved things. Something like
| https://en.wikipedia.org/wiki/Hydrothermal_vent
|
| And you may even have some floating islands made of pumice
| https://en.wikipedia.org/wiki/Pumice_raft
| neurobashing wrote:
| If we're collecting scifi references to water planets, "Neptune's
| Brood" by Charlie Stross features a very large water world, and
| the problems of certain minerals (like uranium) dissolved in the
| oceans. Also the fun things that happens to ice under extreme
| pressure.
| melony wrote:
| I am surprised more cryptocurrency people do not read Stross.
| His books feature many speculative examples of crypto backed
| transactions.
|
| Long live robo kitty!
| jsw97 wrote:
| They already know about us.
| ornornor wrote:
| That's fascinating.
|
| > As soon as we can, we will book time on Webb to observe this
| strange and wonderful world.
|
| How does that work? Is there a hotline you call to book time? Is
| it free or paid? How is the instrument not booked solid for the
| next few years?
| criddell wrote:
| As I understand it, you write a proposal:
|
| https://www.space.com/james-webb-space-telescope-observing-t...
| ornornor wrote:
| Interesting read, thanks.
| raattgift wrote:
| To give you an idea, Hubble Space Telescope observation
| proposals look like this
| <https://www.stsci.edu/hst/phase2-public/16642.pdf> and
| <https://www.stsci.edu/hst/phase2-public/16701.pdf> (chosen
| because these two are what the HST has been doing in the
| couple of hours before I typed this). The ABSTRACT sections
| are probably the parts most of interest to you.
|
| PS: <https://spacetelescopelive.org/latest> might also be
| of interest over time, as that will eventually report what
| Webb is looking at.
| smm11 wrote:
| As soon as I hear "light years" things start sounding a lot like
| religion.
| dougmwne wrote:
| In what way? It's a simple measure of distance talking about
| directly observable objects.
| ChrisMarshallNY wrote:
| Reminds me of the "mountains" scene, from _Interstellar_.
|
| https://youtu.be/4Hf_XkgE1d0?t=90
| dotnet00 wrote:
| A potentially worthy target for some atmospheric spectroscopy
| from JWST?
| LeifCarrotson wrote:
| They say as much in the abstract:
|
| > The water world candidate TOI-1452 b is a prime target for
| future atmospheric characterization with JWST, featuring a
| Transmission Spectroscopy Metric similar to other well-known
| temperate small planets such as LHS 1140 b and K2-18 b. The
| system is located near Webb's northern Continuous Viewing Zone,
| implying that it can be followed at almost any moment of the
| year.
| hey_bear wrote:
| Technically second planet covered in liquid water... they clearly
| forgot about Earth
| xwdv wrote:
| Earth is not an exoplanet, it is merely a planet.
| hey_bear wrote:
| "merely a planet", it's sad that the thing that gives
| everything life and beauty and wonder can be so easily
| dismissed nowadays...
| mycocola wrote:
| You can't be serious. By definition exoplanets are planets
| outside our solar system.
|
| If you want to be romantic about it, feel free to consider
| the hunt for exoplanets a challenge to confirm that there
| is no planet equal to Earth.
| _Algernon_ wrote:
| You're either misreading every comment intentionally, or
| really dense.
| anthropodie wrote:
| Only planet with Life. I sometimes wish people ponder on
| that for some time. Maybe they will have a new found
| respect for this planet like I did. Took me a while but
| when I fully grasped the concept of Life few years back and
| read and saw all the life less rocks in our solar system it
| changed the way I look at things. Still amazes me when I
| think about it.
| TheBigSalad wrote:
| Only planet with life based on what? We haven't been to
| other planets.
| svachalek wrote:
| Only planet known to harbor life. Life, at least single
| celled life, may be fairly common out there but we can't
| be sure.
| xwdv wrote:
| I only find it amazing the way any other low probability
| event would be amazing. Nothing more. Like finding a
| collision between two GUIDs or something
| k__ wrote:
| Is it an endo or a mesoplanet?
| Tade0 wrote:
| It's around 100 light years away from Earth for anyone
| interested.
| tiffanyh wrote:
| So the distance would be like a weekend getaway when it comes
| to space travel.
| nekoashide wrote:
| Programming machines to make the trip and then seeding with
| human life seems to be the best answer to distance.
| xwdv wrote:
| I doubt this. We seem very hesitant to seed any world with
| any kind of life, even going through great lengths to ensure
| no errant bacteria get carried on a rover or something.
|
| If we were serious about spreading life, we could loaded up
| some rockets with basic organisms and throw them onto
| whatever worlds we want to seed, and then a few million years
| of evolution should take care of the rest.
| cstever wrote:
| I have enjoyed reading "The Songs of Distant Earth" by Arthur
| C. Clarke which talks about seed ships and the culture rise
| from that. It's an interesting read.
| barbazoo wrote:
| Another book along those lines I enjoyed reading was
| "Children of Time" by Adrian Tchaikovsky.
| detritus wrote:
| Wonderfully written, but for my shame I expected a
| different storyline and put it down a year or so ago
| after only reading 60 pages or so and haven't gone back
| to it. I keep packing it one times away, but... .
|
| One day I might learn how to have a kid AND read books :/
| myko wrote:
| I started reading the Foundation trilogy out loud to my
| infant. One gets through the books a lot more slowly but
| it works! I must admit that even if he falls asleep I'll
| cheat and finish the chapter (still reading vocally).
|
| Bonus: it lets me practice voices for DM'ing DnD games
| koheripbal wrote:
| The seeds of humanity won't be humanity at all, but the AI.
| skrebbel wrote:
| I'm imagining a spaceship landing at a deserted planet
| millions of years in the future and then just sitting
| there, generating pictures of cities in the sky and Mona
| Lisa on a surfboard.
| TheOtherHobbes wrote:
| It's all fun and games until you think about the
| practicalities of building a self-repairing machine that
| can keep running for hundreds/thousands/millions of years
| with no significant software or hardware errors.
| bqmjjx0kac wrote:
| Specifically without becoming a paperclip optimizer.
| narrator wrote:
| It seems that there's a very pessimistic trend with
| regards to estimating the feasibility of engineering
| human biology for inhabiting outer space. Everyone just
| wants to let AI do it. I think this is because the
| progress of biotech has been so glacial. This is largely
| due to regulation. China will probably change the rules
| around at some point to allow for more flexibility here,
| with lots of moral outrage and handwringing in the west,
| and speed off into the future.
| partdavid wrote:
| Well, I think that's really just an implementation
| detail. The point is that we will engineer our successor
| beings, whether than engineering is computery or mad
| sciencey or both.
| bpodgursky wrote:
| Kind of a fun hybrid where AI is clearly dominant in an
| established solar system, but it ends up being impossible
| to miniaturize the enormous supply chain necessary to
| fabricate microprocessors, so to colonize a new solar
| system it actually ends up being necessary to send self-
| replicating carbon-based humans who will then bootstrap
| the industrial supply chain necessary for AGI.
|
| (repeat ad infinitum for the rest of the galaxy, humans
| live only on the frontier)
| ianmcgowan wrote:
| I'd buy that book!
| phh wrote:
| Who came first? The AGI or the human?
| TheBigSalad wrote:
| For what reason would we want people physically close to this
| thing?
| [deleted]
| bilsbie wrote:
| Who would raise them?
| Centmo wrote:
| The robot from _I Am Mother_
| metalliqaz wrote:
| I have thought about this a lot. I have said for a long time
| that human space exploration doesn't make any sense to me.
| Space is so hostile to our life in general it seems that only
| purpose-built machines make any sense for the job. But of
| course for the preservation of our species, we would want to
| be able to send the "seeds" of our ecosystem to other places.
|
| But then, if we have progressed to that level of technology,
| where we can send cells or even just DNA with the machines to
| be cultivated far away in the distant future... would we even
| bother? Would we even consider ourselves distinct from the
| machines by then? Honestly I'm not sure. It could very well
| be that we consider our creations to be our "children", so to
| speak. Destined to inherit the universe as we pass gradually
| into the dust from from which we came. It seems inevitable if
| we eventually crack AGI or artificial consciousness.
| [deleted]
| znpy wrote:
| > But of course for the preservation of our species, we
| would want to be able to send the "seeds" of our ecosystem
| to other places.
|
| Or we could, you know, take better care of the planet we're
| already on.
| ItsTooMuch wrote:
| Tell that to the solar flare that randomly burns
| everything on it... Or the asteroid that crashes into
| it... Or the black hole that eats it... Or the aliens
| that invade it... Or the plague that kills everyone on
| it... Or the supervolcano that causes "nuclear" winter...
|
| We could be doing our absolute best and still be
| _surprised pikachus_ anyways. And there 's no scifi
| remedy that will help us resolve these problems, we're
| not even K1, much less K2 - who's on Earth when it comes
| dies.
|
| As the only known example of intelligent life in the
| observable universe, we should be doing everything we can
| to preserve ourselves. Having everyone on one planet is
| not a good idea if you're looking for survival on
| geological timescales (and/or have bad luck).
| Melatonic wrote:
| We would probably be better off seeding just some basic
| life first well before humans - give it time to adapt to
| the local environment and setup shop. Of course this could
| also backfire (in that it might evolve to be very hostile
| to human life) but if there is one thing humans are amazing
| at it is outcompeting other potentially hostile forms of
| life.
| koheripbal wrote:
| I think the AI will find little reason to take us with them
| to the stars.
| semi-extrinsic wrote:
| I don't understand people who say things like this. If we
| invented AGI tomorrow, how would it achieve domination
| over us humans?
|
| It is like Voltaire, Rousseau, Locke, Milton, Hobbes,
| Rawls never even existed and we don't have any sort of
| coherent understanding of political philosophy and how
| power is gained and enacted at the consent of the
| governed.
|
| I also find that discussions of interstellar travel tend
| to conveniently ignore the fact that a society that
| develops to the point where this is feasible, must
| necessarily also have developed to the point of a fully
| post-growth economy, which leads to fundamental questions
| of why that society (or parts of it) would seek to
| undertake interstellar travel at all. It's a boring
| answer, sure, but many facts of life are quite boring.
| cityofdelusion wrote:
| > If we invented AGI tomorrow, how would it achieve
| domination over us humans?
|
| Completely depends on if super-intelligence is possible
| from that AGI model, and if so, how fast the ramp up will
| be to super-intelligence.
|
| The problem for insects is not that humans "dominate"
| them (in fact most insects have total "freedom"); the
| problem is that humans do not take the concerns of
| insects into account for any of their decision making.
| koheripbal wrote:
| It is a bit of hubris for us to think that we are the ones to
| travel the stars and not the AI we create.
|
| The "robots" will have little incentive to seed humans when
| they get there.
| gscott wrote:
| We don't need to bring humans we can bring some sort of
| fungus and eventually it will evolve into humans over
| billions of years.
| whatshisface wrote:
| Fortunately my blender doesn't need an incentive to grind
| fruit, only a hundred and twenty volts.
| bumby wrote:
| Ah, but what makes you confident humans (or any other
| animal) isn't likewise acting deterministically with just
| a veiled illusion of free-will and incentive?
| dreen wrote:
| From physics point of view, I guess everything is
| deterministic. But from a human point of view, the
| question is irrelevant, because we can only experience
| reality as humans.
| freedomben wrote:
| Your question sounds like a troll, but it's actually a
| fascinating one. Reminds me so much of reading Descartes
| and essentially asking, "How do I know I'm not asleep and
| dreaming?"
| hypertele-Xii wrote:
| You know you're awake because reality has continuity and
| makes sense.
|
| Conversely, dreams are fragmented and implausible. You
| can train yourself to check this to lucid dream (become
| aware that you are dreaming).
| bil7 wrote:
| I've had vivid dreams where I was completely convinced I
| was in reality. Continuity was maintained well enough to
| fool me. How could I know I wasn't in a dream? How can I
| truly know beyond doubt that I am not in a dream?
| freedomben wrote:
| Yes you can sometimes do that (I've lucid dreamed quite a
| few times before and it's pretty wild), but it's nowhere
| near 100% reliable. you can get pretty good with
| practice, but even then it's not a scientific test. It's
| more of a process of reasoning and gut checking. The
| human mind can fill in an incredible amount of detail
| when needed. In one lucid dream I was playing a song on
| the guitar that I had (as far as I know) never heard
| before (myself in the dream was inventing the song). I
| realized I was dreaming before waking up and practiced
| the song over and over so it was stuck in my head, and
| then immediately after waking I wrote down the tablature.
| It ended up being a pretty good song, and (at least so
| far) I haven't heard anything else like it.
|
| Obviously this is heavy anecdata, but I've never heard a
| scientific explanation of how to be certain whether or
| not you're dreaming (or as Descartes describes, being
| deceived by a demon).
| bumby wrote:
| > _it 's not a scientific test._
|
| Isn't every subjective experience, almost by definition,
| unable to be tested scientifically?
|
| We can objectively measure someone's brain activity
| during sleep, but we can't really measure their
| subjective experience. Implying that everything made up
| of subjective experience (like consciousness) can't be
| measured. Which also implies it can't be proven by
| scientific means. So in response to the GP comment, I'm
| not sure we can "know you're awake" (in the scientific
| sense, at least).
| bil7 wrote:
| I'm pretty sure what you're describing is the hard
| problem of consciousness.
| freedomben wrote:
| Yes, exactly, that's the point I'm getting at. We
| experience "life" through our senses, and our senses can
| be fooled. Even measuring brain activity requires a
| subjective level of "trust" that we're seeing a real
| machine that's taking real measurements, rather than a
| simulation of a machine. We can look for glitches in the
| matrix, but absence of evidence isn't evidence of
| absence.
|
| It's wildly impractical to live your life like that, but
| at the end of the day we just don't know and probably
| can't know.
| bumby wrote:
| Sorry if it came across that way, it definitely wasn't
| the intent! I think Sam Harris has some pretty
| fascinating and accessible discussions on the topic.
| There's also some interesting neuroscience work that
| seems to conflict with the common notions of free-will.
| freedomben wrote:
| oh yeah, totally agree Sam Harris on this is really
| awesome. I also love Robert Sapolsky's stuff. He's got
| several great videos on Youtube and his books are awesome
| as well.
| 0xdeadbeefbabe wrote:
| Liking fruit is far from being an automaton.
| bumby wrote:
| Can you elaborate? It's not immediately clear to me what
| you meant. Can not both simple and complex decisions be
| the artifact of a deterministic process?
| [deleted]
| [deleted]
| quadcore wrote:
| Your blender didnt learn survival from you. Yet.
| dsQTbR7Y5mRHnZv wrote:
| they've probably already done that to us here on earth
| scohesc wrote:
| That would be so interesting - could be many a sci-fi stories
| created on that premise.
|
| Some mechanical robot/starship storing frozen embryos for 100
| years to be released on a far-away exoplanet, the starship
| taking care of them while they grow up and learn how to live
| on this new world - the beginnings of a new civilization - a
| technological adam and eve of sorts.
| boxed wrote:
| http://localroger.com/k5host/pitv.html is my favorite take
| on this
| 1ko wrote:
| Raised by wolves
| z3c0 wrote:
| And Interstellar
| lhuser123 wrote:
| I am Mother https://en.m.wikipedia.org/wiki/I_Am_Mother
| killyourcar wrote:
| And 2001 Nights.
| Larrikin wrote:
| But hopefully the story would actually be interesting
| blywi wrote:
| The best exploration of this theme that I have read, was an
| East German SF novel from the former GDR. Unfortunately, as
| far as I know, it has never been translated into English.
|
| Here is a very short synopsis on the authors website in
| English: https://steinmuller.de/en/sf-literatur/science-
| fiction-buech...
| prox wrote:
| We can't do lightspeed with the best tech available, so
| it's more like 300-400 years probably.
| ryandrake wrote:
| Don't have to go light speed, thanks to relativity. If we
| could achieve and sustain even 1G acceleration, live
| humans could make the 100LY trip in approx. 9 years
| (spaceship time). You could leave, visit the planet, and
| come back only 18 years older and tell the next-next-
| next-next-next generation all about it.
|
| EDIT: To be fair, 1G over 100LY will result in a maximum
| speed around 0.9998c so I guess you _would_ have to
| approximately approach light speed for this trip.
| egberts1 wrote:
| cut that is half. You have got to decelerate to a near
| stop, much less zip past by your target.
| euroderf wrote:
| Better stock up on antimatter.
| sliken wrote:
| True, but we can only manage 1G for minutes, and even
| hours is a pretty far off.
|
| Without exotic tech like anti-matter or bending space
| time nothing is particularly close to light speed. Even
| city size laser arrays are targeting 1-3% of light speed
| .... for a few grams!
|
| It's a mind boggling amount of energy to get any decent
| fraction of the speed of light, even without the
| relativistic increases in mass.
| Melatonic wrote:
| Is this really how time dilation works?
| somenameforme wrote:
| Yip, although there's also length contraction in play.
| The universe just starts contorting itself to ensure
| nothing ever exceeds the speed of light.
|
| What the GP post is referring to is called a
| 'relativistic rocket'. You can find plenty of calculators
| for them, like here [1]. It leads to really mind-bending
| scenarios. For instance a single human could easily
| travel a billion light years within their lifetime,
| requiring "only" to travel at 1G acceleration for 40
| years. Of course in that time a billion years would have
| really passed outside of our relativistic rocket.
|
| If it ultimately turns out that there is no fundamental
| law of the universe that makes long-term rates of
| relatively low acceleration impossible, then the future
| will be a simply unimaginable place. Time itself will
| start to lose meaning as it becomes as variable as
| distance is today, at least for those able to travel.
|
| [1] -
| https://www.anycalculator.com/starshipcalculator.html
| ryandrake wrote:
| Yea, the calculators really help show how wild it is. I
| could outlive Earth's sun by simply accelerating away at
| 1.25G for ~35 years (ship time), not to mention how
| stacked I'd be from the workout of merely existing at
| 1.25G for half my life. The very concept of simultaneity
| is completely whack at such distances, times, and speeds.
| 7thaccount wrote:
| Speed through space + Time adds up to the speed of light
| or something like that (not a physicist). So as you get
| closer and closer to the speed of light, your motion
| through time (from your point of view) slows
| tremendously. So a few years to you, could be centuries
| to outside observers. Source: some Kip Thorne lectures I
| saw like 15 years ago.
| ant6n wrote:
| At those speeds you will have problems with the rocket
| equation even if you have an mass-to-energy drive.
| hoosieree wrote:
| Mo' acceleration, mo' trolley problems.
|
| Go on vacation; come back; everyone's dead.
| bergenty wrote:
| Alright, alright, alright.
| bergenty wrote:
| We'll never get governments to approve and fund this.
| Elon/Bill if you're reading this you have to do this going
| rogue. Make it happen. Send human life out to a hundred
| different planets!
| OkayPhysicist wrote:
| I feel like the reverse situation kinda writes itself as a
| sci-fi horror short story:
|
| You've got people living their every day lives, when a
| probe from space lands and starts producing aliens. At
| first it's treated as a strange curiosity, but with time
| the aliens begin to make inroads conquering the planet.
| Ending twist: the aliens are humans, and the "people" were
| aliens!
| jra_samba wrote:
| "And All The Stars, A Stage", by James Blish.
| elliekelly wrote:
| You might enjoy the short story collection _Children of the
| New World_ [1] by Alexander Weinstein. One of the stories,
| _Saying Goodbye to Yang_ , was recently made into a movie
| called _After Yang_ [2] staring Colin Farrell. The movie
| has a super-catchy opening credit sequence.[3]
|
| [1]https://app.thestorygraph.com/books/31cd88d8-d8d3-4414-b
| 38c-...
|
| [2]https://boxd.it/lx5a
|
| [3]https://twitter.com/A24/status/1499114323314151425?ref_s
| rc=t...
| lux wrote:
| Let's gooo!
| WalterBright wrote:
| Since it's heavier than Earth, what about the rocket equation?
| Colonizing it may mean the inhabitants could never leave it.
| vikingerik wrote:
| There are non-rocket ways to space, like a catapult or maglev
| accelerator. Or ways to assist the rocket outside the rocket
| equation, like a spaceplane launch platform. Or even Project
| Orion nuclear explosion propulsion. (Which is subject to the
| rocket equation, but with nuclear rather than chemical fuel
| for a much higher multiplier of energy per mass.)
| WalterBright wrote:
| I'm skeptical a catapult could ever work in an atmosphere
| as thick as Earth's. The drag would be incredible.
| perihelions wrote:
| It'd just be 13 km/s to low orbit (or 19 km/s to escape),
| which isn't really that much for small payloads -- New
| Horizons had a total of 17 km/s delta-v. You don't even need
| to look at space elevators or fission or fusion launch
| systems, all of which are probably viable on first
| principles.
| vikingerik wrote:
| That orbit or escape velocity really is that much. The
| rocket equation is exponential, such that even a small
| change in the required speed means a large change in
| requirements. The difference between Earth's escape
| velocity of 11 km/s and this planet's of 19 is actually
| quite huge. Imagine you build an 11 km/s rocket as you
| would on Earth... to get it off this other planet, first
| you have to accelerate that rocket _and all its fuel_ to 8
| km /s.
|
| The rocket equation is Dv = Ve ln (m0 / m1), where Ve is
| exhaust velocity, m0 is payload mass, m1 is mass including
| fuel. To get 19/11 as much Dv, you need a fuel/mass ratio
| of e^(19/11) = 5.6 times greater.
| Symmetry wrote:
| We're not getting to a planet 100 light years away with
| chemical rockets so presumably the future inhabitants will be
| able to use high efficiency rockets to leave it.
| notfish wrote:
| I don't think interstellar travel necessarily implies much
| better tech than we currently have. I mean, Project Orion
| style nuke-powered spaceships can get you there in a
| lifetime but unless you wanna nuke your colony whenever
| someone needs to leave you still might be stuck on the
| surface.
| google234123 wrote:
| What? A nuke in space will have very little impact on a
| planet. A nuke on a planet doesn't have much impact on
| the planet either: see all the tests done on earth.
| marcosdumay wrote:
| It's a non-trivial number of nukes on every single
| launch. If it becomes popular, it will have a very
| noticeable effect on a planet.
|
| Nuclear propulsion isn't the only alternative we have for
| reaching low orbits. Land-powered rockets are probably
| much better, and there is always the odd high-elevation
| rail or space elevator (but those get bad fast on large
| planets).
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