On Mar 9, 6:11=A0pm, Douglas Berry <penguin_...@[EMAIL PROTECTED]
>
wrote:
>> The idea was brought up by Marshall T. Savage and is part of his
>> Millenial Project ('colonizing the galaxy in 8 easy steps').
To give proper credit, it was around long before Savages use of it.
The "Millenial Project" (1992, right?) is interesting, but there's not
a whole lot of novel material in it. Basically the idea of slapping
the poles with ices has two possible motivations: impact
devolatilization of the polar regolith, or wholesale im****tation of
volatiles. Both were proposed and worked out at least in the 80's, if
not before, and both are possible if ambitious. Personally I think the
crux is getting enough N2 there, not getting enough atmosphere there
(there's plenty of CO2 likely locked in the regolith).
> The problem is Mars' lack of an active core to renew the atmosphere.
> In a relatively short time (in geological terms) the g***** and
> liquids liberated from the comet will be lost to space.
You might want to look at the timescale for that. Jean's escape
(thermal loss of the atmosphere) is not going to be significant. For a
CO2-dominated atmosphere, the exosphere temperature is likely low
(Venus is only 285 K), and the mean molecular weight high (CO2 =3D 44):
v_rms =3D sqrt( 3 * 300 * (8314/4) ) =3D 432 [m/s]
v_esc =3D 5000 [m/s]
(For comparison, this ratio is better than the one Titan has ended up
with, & it has plenty of atmosphere still hanging around).
If you assume an N2-dominated atmosphere, v_rms is faster, but not
terribly:
v_rms =3D sqrt( 3 * 1000 * (8314/28) ) =3D 944 [m/s]
Even that's enough for the atmospheric lifetime to be measured in 10's
of *millions* of years. Keep in mind that even "a few tens of
thousands of years" is several times longer than written human
history... and for a Martian atmosphere, we're talking in the
neighborhood of "long enough to go extinct several times over".
--
Brian Davis
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