Naraht wrote:
>This is more sort of a research question.
>
>Presuming a planet with more or less the same makeup of the solid
>portion, the same age, and same distance from the sun, how large or
>small can the planet be to be habitable by humans? I *think* the
>primary issue is that if it is larger than a certain size then the
>planet won't lose the Hydrogen/Helium in the atmosphere and become a
>close in Gas Giant and if it is smaller than a certain size, it won't
>keep it's Oxygen long enough (which puts the minimum somewhat larger
>than Mars (or would Mars have kept its oxygen if it had a
>Magnetosphere)).
Niven's various stories in the seventies figured that Earth would have
kept too much atmosphere if it hadn't had a moon stirring the top and
pulling off air molecules and tossing them around.
--
Tomorrow is today already.
Greg Goss, 1989-01-27 |
