In the far future, a fleet of human settlers arrives in a star system containing an unusual planet; 90 times the mass of Earth, with only 3 times the radius. Rocky planets with similar mass are known to exist, such as Kepler-277b, but this is the first in the habitable zone of a star. It hasn't evolved complex life of its own, so the colonists decide to introduce Earth-based organisms. The planet has a shallow ocean covering 40% of the surface. The colonists alter the atmosphere to be similar in composition to Earth's.

What flora and fauna could survive on this planet?

  • $\begingroup$ Tardigrades (aka waterbears) are apparently unkillable :-) cnet.com/news/… $\endgroup$
    – JonSG
    Jul 29, 2021 at 22:11
  • $\begingroup$ An awful lot of bacteria and microscopic organisms are too small to be bothered with gravity (other forces are overwhelmingly larger in proportion on that scale), so yeah, lots. Oxygen partial-pressure is a thing. What's that on your planet? (Hint, it gets really toxic at high pressure). $\endgroup$ Jul 29, 2021 at 23:11
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    $\begingroup$ @ARogueAnt. It's similar to Earth when it comes to the atmosphere in terms of composition and pressure. $\endgroup$ Jul 31, 2021 at 4:21

1 Answer 1


This would be about 10 Gs. Bacteria could survive it; this was actually tested. Deep sea fish and other deep sea organisms could probably survive it, though at a 10x shallower water depth. Although, 10 Gs of gravity is different from high pressure deep under water because it also affects the weight of the organism itself. It's possible that could have developmental effects that would keep it from growing properly; the higher gravity could pull heavier tissue types out of place relative to the lighter tissue types, causing malformation.

Few if any land animals could survive it; smaller organisms would have an advantage, but even for insects, it would still be far out of the conditions they evolved for. They would probably not develop or behave properly to survive, and their food requirements would be much higher because they would be moving around ten times the weight all the time. Lichen and some land plants might be ok, but would grow smaller and flatter.


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