Not that I WANT to terraform Mars...

From: "Combs, Mike"
To:
Sent: Monday, July 16, 2001 10:17 AM
Subject: RE: [spacesettlers] Not that I WANT to terraform Mars...

> Especially if we're going to try and get by with an atmosphere only about
> 1/3 the density of Earth-normal.
>

Uh, I've heard Martians talking about giving a 1/3 *bar* atmosphere to Mars.
That means an atmosphere exerting 1/3 of the atmospheric pressure of Earth
at sea level. Since the Martian gravity is around 1/3 g, then in fact you
would have to have a column of air with 10 metric tones of mass above each
square meter of the Martian surface - the same value on Earth. So, although
exerting less pressure, this atmosphere would provide as much passive
shielding as Earth's, because cosmic rays would have to pass through 10
tones of air in either planet. Or am I missing something?

> You may well have uncovered yet another difficulty that the terraformers
> tend to gloss over.
>

Even if the passive atmospheric shielding is really not enough, I think that
a terraformer could argue that a radioactive surface is not exactly an
unsolvable problem. People could live in underground houses and so get
exposed to cosmic rays only during brief periods of time (after all, most
people spend the vast majority of their time indoors). As for agriculture,
well, plants don't care about cosmic rays. However, I think that polar bears
and seals crawling over Mars, like K.S. Robinson imagined, would not be a
likely sight...

> Regards,
>

Regards,

> Mike Combs
[snikt]

Lucio Coelho