Crashing Planets Together

On Nov 13, 2003, at 6:29 AM, Lynn Olson wrote:

> Venus is about 5000 times as massive as Ceres. If Ceres can produce
> 150
> times the surface area of the earth (see the bottom of Al Globus'
> messages),

The 150 figure assumed shielding roughly equal to twice the mass of the
atmosphere over one spot on the Earth. A earlier discussion on this
group convinced me (although I still have some checking to do) that the
factor of 2 is unnecessary, so we should be able to get about 300 times
the surface area of the Earth. Of course, this is a minor correction.
The important point is that the potential real estate is enormous by
any standard.

The dinosaurs were destroyed by an asteroid because they weren't
space-faring. It's almost as if Gaia then thought "Well, dinosaurs
worked pretty well, but space-faring is necessary. Maybe I'll should
try mammals this time." Humanity is now developing systems to detect
and deflect asteroids, and could build orbital space colonies to spread
beyond Earth to insure life would survive a planetary catastrophe.

Al Globus
CSC at NASA Ames Research Center
http://www.nas.nasa.gov/~globus/home.html

Views expressed in this email are only my opinions and are not the
position of any organization I'm familiar with.