Super-Earths are ideal targets in the search for life
singularityhub.com
singularityhub.com
What would be the energy source to sustain life on an ejected super-Earth? Radioactivity? Tidal forces from orbiting moons?
I can’t imagine geothermal supporting as vibrant an ecosystem as photons pouring in everyday allow photosynthesis to do.
"The team found that planets 10 times the mass of the Earth, with an atmosphere 100 to 1000 times thicker than Earth’s, may be the most favorable for storing life for billions of years. But to do this, they must orbit the star at a distance that the orbit of Mars occupies in the Solar System. At such a potentially safe distance, the original atmospheres can act as greenhouse gases, absorbing infrared radiation, providing the necessary heat and pressure that can support life in oceans of liquid water."
So the planet is not ejected from the system, just pushed out so that instead of an orbit of days it is as far away as Mars is to our sun (1.5 AU). Gell-Mann Amnesia comes into play here.
[1] https://universemagazine.com/en/life-on-super-earths-can-exi...
Digging one link farther reveals the original article [2] which is more detailed and descriptive than the others. The original article explores super-Earths where the primordial H–He atmosphere is retained and traps enough heat to sustain liquid water, and includes simulations of “unbound” super-Earths that are ejected from their star systems. The mathematical model [3] incorporates the initial heat from planet formation and radiogenic heat but does not mention tidal forces.
[2]: https://www.nature.com/articles/s41550-022-01699-8
[3]: https://github.com/mollous/Data_Liquid_Water_Conditions
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The original article also includes this discussion of habitability:
Life on the type of planet described in this work would live under considerably different conditions than most life on Earth. The surface pressures in our results are on the order of 100–1,000bar, the pressure range of oceanic floors and trenches. There is no theoretical pressure limit on life, and some of the most extreme examples in Earth’s biosphere thrive at ~500bar. These habitats also receive a negligible amount of direct sunlight, and therefore photosynthesis would not be an optional mechanism to provide for metabolism. Chemoautotrophic life on Earth would be a more likely analogue to possible life on this type of planet.
Also a rogue planet without a star might be able to sustain simple life but without human sources of nuclear power the only source of energy would be geothermal, so not exactly exciting candidates for living. Also who wants to live in a planet in perpetual darkness?
Either the “astronomer” author wasn’t a real astronomer at all or this is just clickbait.
Are red dwarf planets over represented due to detection methods?
Or is there some sort of astrophysics related reason red dwarfs would be more likely to have super earth class planets in orbit?
Basically should we hold out hope that with better detection techniques we will be able to detect more planets that are similar to our own.
I am also convinced we will find planets better suited for us than earth eventually. But I doubt any of them would be in any meaningful close distance.
Even if you can imagine a 100 year or 500 year ship (like in Expanse) that can get to a planet 10 LYs away, imagine if it’s 100 or more. We might be SOL.
The Earth of the future, not so much.
We don't need an ideal climate to flourish. That's part of our species' strength: our remarkable ability to adapt.
But no, they specifically said most of them are not orbiting red dwarfs:
> Most super-Earths orbit cool dwarf stars, which are lower in mass and live much longer than the sun.
Also apparently the planets will never be brighter than sunset in earth. The author could have at least mention some of the potential problems. I stand by calling this article disingenuous.
The statement, "scientists have found super-Earths orbiting 40 percent of cool dwarfs", specifically links to an article discussing red dwarfs: http://www.inaf.it/en/inaf-news/billions-of-rocky-planets-in... That article quotes the author of an ESO HARPS planetary survey paper: “[o]ur new observations with HARPS mean that about 40% of all red dwarf stars have a super-Earth orbiting in the habitable zone where liquid water can exist on the surface of the planet".
Cool dwarfs seems to be a direct reference to red dwarfs.
I'd guess in that case people would be living underground in artificially lit environments...
This idea has already been explored by sci-fi. One instance that comes to mind is Wandering Earth where the premise is that people turned the Earth into a planet scale space vessel to escape the sun's expansion and "rehome" the Earth. I'd suggest reading the book rather than watching the movie based on it though.
-- https://www.as.arizona.edu/people/faculty/chris-impey
Naturally, none of this makes him right... I have no judgement on that point. But does clear some of the ad hominem.
one could say his career depends on selling this idea that these exoplanets are awesome sauce. Maybe it’s even worse?
> Either the “astronomer” author wasn’t a real astronomer at all or this is just clickbait.
Well it turns out he is a real astronomer, and doesn't appear to be a "hack" either as you also said he was.
"If a super-Earth is ejected from its star system and has a dense atmosphere and watery surface, it could sustain life for tens of billions of years, far longer than life on Earth could persist before the sun dies."
is wrong according to the article it references in support. See this comment for details[1].
I'm rather taken with this idea of billions of rogue planets, wandering around the Milky Way, carrying life that's billions of years old. Such a rogue might get captured by a star-system's Oort cloud, gradually drift towards the star, and eventully evince more complicated life. In fact I'm not aware of strong evidence that Earth isn't a rogue (it's about the same age as the Sun, but that's circumstantial, right?)
So yes life can be probably only sub-surface one, but that's generally a tough proposition living off what... geothermal vents and volcanic activity? That's hardly a recipe for anything advanced, regardless of time given to evolve.
Just imagine the effort to get one satellite up. Now this would open the door for them to find new ways to make it to orbit.
https://en.wikipedia.org/wiki/Project_Orion_(nuclear_propuls...
I think the Orion project people spoke of a spaceship the size of a large hotel; with plenty of lead for screening cosmic rays. They claimed there'd be so much lifting capacity that keeping weight down wouldn't be an issue - you could have a barbershop with real barber's chairs.
I don't see much future in this kind of design. But I also don't see much future for human space exploration without truly gigantic spaceships. I suppose the alternative is to assemble the ship in orbit, using hundreds of chemical-powered supply missions.
https://space.stackexchange.com/questions/14383/how-much-big...
One doesn't have to go too much larger before it is impractical to get off the planet with even the best theoretical chemical rockets.
edit: "That critical size, according to Arnscheidt and the other authors of the study, is 2.7 percent the mass of Earth. They say that any smaller than that, and the planet simply won’t be able to hold onto its atmosphere and water long enough for life to appear." shorturl.at/bdgIK
So, a mercury sized planet could hold an atmosphere in theory, and require around 1/3 the velocity to escape (vs. earth)
https://www.nasa.gov/press-release/nasas-maven-reveals-most-...
https://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.10...
...not saying this is directly applicable, but maybe food for thought?
https://arxiv.org/pdf/1803.11384.pdf
On a super earth, such as Kepler 20b ( https://en.wikipedia.org/wiki/Kepler-20b ) in order to lift 1 ton of mass to orbit, it would need 9000 tons of fuel -- about 3x larger than the Saturn V. To get the JWST off the planet, it would take 55,000t of fuel. To get that 45t of an Apollo mission off the planet, it would take about 400,000t of fuel over 100x more than the fuel needed for Saturn V.
Want to be a gym bro, or do you want to just visit a super earth for a couple years?
I suppose somewhere in the universe there could be a dust cloud of pure lithium that eventually coalesces into a planet, but that seems extremely unlikely. (Interesting premise for a SF story though.)
Wouldn't this be impossible because of the planet's molten core? Or am I just biased because our planet has a molten core and I'm assuming it's necessary for a life-bearing planet, or at least unavoidable for any planet where its host star hasn't burned out from old age?
Finally, even if you could remove the molten (or solid) core of a planet, wouldn't the shell collapse due to gravity and other forces?
It seems to me that all these planetary engineering ideas really don't make that much sense. If you have such advanced technology that you can do these things, wouldn't it be faster and easier to build an O'neill cylinder and get exactly the environmental conditions you desire?
IMO, it is pretty notable that the acceleration at the surface is only linearly proportional the the radius for a constant density, I'd expect something much worse.
Of course we can play with the density but chemistry is, like, way harder than physics.
If we focus on settling planets, then each planet is its own set of problems.
But if we focus on learning to live in space, then although it may be harder initially, it's a single problem to solve. Then we just keep working and improving on that solution. And there's a lot more space out there than there are habitable planets. And there's a lot more matter and energy out there than are available on those planets.
If it is going to be totally independent of Earth, you'll have to set up the entire industrial base and population of that planet.
If it is going to be economically linked to Earth, then we're going to have to deal with shipping stuff there. And, like, what will they sell to Earth? I guess it would have to be really valuable and specific to that planet, to justify manufacturing it there and then lifting it out of a massive gravity well.
Space colonies at least have the hypothetical benefit of zero-g industry, aren't downwell, and can move around. Space colonies in the asteroid belt are the way to go, IMO.
You can't. It's much, much harder than that.
Getting to any kind of self-sufficiency anywhere is going to be incredibly difficult. You literally have to invent a complete industrial production chain for materials, machinery, and food and air that operates in a completely different and much more hostile physical environment with a completely different mix of available raw materials, much less solar energy, and no initial biosphere.
https://en.wikipedia.org/wiki/Colonization_of_Venus#Aerostat...
Colonizing planets outside the solar system seems to require some sort of sci-fi technology just to get there, so it is hard to speculate. If we're going to assume we can somehow get to Alpha Centauri, we might as well also assume that when we get there we can use nanobot magic or whatever to transform the colonists into an alternative form that is compatible with whatever environment we find there.
That, again, is a pretty big new constraint you are placing to make an argument.
Since we're talking about exo-planets, that's not a reasonable constraint in this conversation.
> Colonizing planets outside the solar system seems to require some sort of sci-fi technology
Yes - yet that's the context of this thread.
Anyway, if you pick apart the problems described in the first post you responded to, you'll find, I think, that the only restriction imposed by limiting the discussion to planets inside the solar system is the "less solar energy."
yes, but we already know how to solve these problems. living in an atmosphere on terra firma with resources is something we can do.
>although it may be harder initially, it's a single problem to solve
hmm, and as of now these are unobtainable solutions: unlimited power source, radiation shielding, etc. so unless one of these planets has a more advanced race that can share how to get over these little hurdles, this plan is just sci-fi
To me, exoplanet surveys are one of the most exciting forms of science. I can think of no other thing that would bring us closer to understanding whether or not life does exist in our universe beyond us.
I've long held that it does, but it feels to me that belief is practically religious, completely unfounded. Combined with the fact that I think no other event will impact our world for the better more than knowing this universe has other life... I have my fingers crossed for the giant ground-based teles they listed at the end. Godspeed
As you said, yeah it's a leap of faith without (at least publicly available) empirical evidence, but who cares. It's fun thinking about the possibilities of others out there, interacting, and sharing with them. Even better if they share their tech so we can travel distances off and away from this crumbling rock.
In any case, I believe we've already been contacted, at least since nuke testing, and that the US andnother govs have recovered craft that are handled by contractors. Watch the doc. It's not woo woo crap. I mean Harry Reid is in it and he implies a lot to say thr least.
Here's a link, just use uBlock to get rid of the ads
Not to me, I'm afraid. Suppose we detect CO2, methane and ammonia in the atmosphere of some exoplanet tens of lightyears away. Hell, suppose we detect definite evidence of life. What difference is that going to make to anything? We couldn't launch a probe that could get there in a lifetime, going at half the speed of light. We certainly couldn't get the probe back again. You'd need a generation ship to get people there.
I'm quite sure there's life out there. I'm also fairly sure that very little of the life out there is organised for (or interested in) interstellar travel; and for most destinations, that life would have evolved by the time of arrival, and the space-traveller would be something that can only live in space. A civilisation that can build a rocket has existed on Earth for only a few decades, and might only last a few decades longer.
We could certainly send a probe to Proxima Centauri. Our great-grandchildren could record the results, if they'd spent two lifetimes keeping the probe in contact and under control (fairly boring astronomy career: maintain contact with a spaceship that was launched before you were born, and won't arrive before your grandchildren have died).
The premise is that humans turned the Earth into a planet-scale space vessel to escape the sun's expansion and rehome into a different solar system. Basically involved de-orbiting the Earth and coming up with a way to fling it out of the solar system whatnot.
The sci-fi parts are quite interesting, though I'd recommend the book instead of the movie (which is really a mediocre Chinese take on the Hollywood blockbuster...)
I quite enjoyed the film. It was interesting to see a different cultural take on how to solve "future problems" in a different cultural SciFi. Would I watch it again? Probably not, was it any worse than the stream of MCU junk? Not really.
Exactly. Hence the "mediocre". It's a familiar storytelling format with a different set of ideological undertones. Nothing special but also not like it's bad or anything.
OTOH, Liu Cixin writes what I would call pretty good sci-fi novels and shorts which the movie doesn't do enough justice to. Then again that's more or less most sci-fi movies compared to their original works.
Is that true?
https://en.wikipedia.org/wiki/Super-Earth
> A super-Earth is an extrasolar planet with a mass higher than Earth's, but substantially below those of the Solar System's ice giants, Uranus and Neptune, which are 14.5 and 17 times Earth's, respectively.[1] The term "super-Earth" refers only to the mass of the planet, and so does not imply anything about the surface conditions or habitability.
> A super-Earth is any rocky planet that is bigger than Earth and smaller than Neptune.
If you read further in the article, it explains why super-Earths are a good target to look at for extraterrestrial life.
I thought Saturn was mostly benign. My hope was that a magnetosphere would protect the moons from the early outbursts of the red dwarf.
> Also energies (delta V) needed to travel between Jupiter moons
That's surprising. Found this nice map [1] and the numbers are really disappointing. ~15 kps from Titan-to-Iapetus sucks (even though it's ~4 kps less than Earth-to-Mars). At least the distances are smaller...
Interesting... The "no" is definitely cheaper and faster than the "maybe" or "yes." If we get a "no", what's next? Planet-wide depression?
So, ~60% denser than Earth? Density is mass/volume, and 2x / 1.25x = 1.6x.
The math works out really well if they meant a 20-30% larger radius: 1.25*3 = 1.95, so similar density but larger volume.
When you start to get into gas giant mass, chemical launch starts to become really close to impossible instead of just wildly unaffordable.
Your space platform would practically have to be a floating city, since mountains won’t even be as high.
Since a lot of such interest is resulting in US federal government funding and I am a US citizen, I have standing, if only as a taxpayer, in this interest.
About this interest and paying to pursue it with my tax money, I ask "Why should I?".
I confess that getting good evidence of such life would be curious, entertaining, fun, etc.
For any in doubt, I will just stipulate that there is a lot of life out there in our galaxy and the rest of the galaxies in the universe. Done. No more wondering or arguing. If you want, I'll also stipulate that they are all little, green, and have 10 legs and 5 eyes. And I will agree that we might find evidence of a Dyson sphere (build a sphere around a sun and collect all or a lot of the energy it radiates).
Second, but I will insist that, from all we know about physics now, there is no way for us ever to have anything like practical two way communications with any life that evolved outside of our solar system.
Third, with current physics, the search for life is at best just curious, entertaining, fun, etc., and, sorry, on these criteria some good movies are better! I can buy a good movie on a DVD for about $10 -- so if I give $10 for the search for that life, I'm all paid up?
Fourth, really, then, the search for such life needs to include a search for some radical new physics. If want to pursue promising research directions in such physics, okay by me, but such research efforts should be low budget unless very promising, and I doubt that there will be any promising directions.
So, net, whatever astronomy, astrophysics, etc. are good for, the search for life that evolved outside of our solar system is not very serious -- or, such life IS there but with current physics there are no significant consequences for us. Sorry 'bout that.
Or, a big effort on the search for such life looks to me like some researchers want to do a big selling job to get taxpayers to give them an interesting career. Sorry 'bout that.
Or, if the search for life is mostly just for a search for some radical new physics, then sell the effort as a search for the physics, not the life. Or I agree already that there is a lot of life out there, but with our current physics there are no consequences for us -- stipulate that they are all green with 5 eyes and get no conflicting data.
Chances of figuring out the upload before we do the extinction are higher imo. This whole AI boom may make it happen sooner than we think. It won't be the upload we all expect ("Am I me in there?") but it'll have human-like thoughts and consume the data we've produced so it'll be us/human in as fluffy a way as we define consciousness right now.
But your variation makes it pertinently clear that it's not "us" who's going to visit those planets, but something else entirely. And why would we need a "super habitable" planet if we're just electrons in a few chips, anyway (ignoring the fact that electronics tends to die in 20 to 30 years of use, but hey)?