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starship-design: Ice Impact Terraforming
Terraforming by Impact
A technique which must become standard in gaining new places to live, is
smashing rocky planets, which orbit in the habitable thermal zone, with ice
bodies from the outer system. Rock worlds which lack a thick atmosphere and
liquid water, can suddenly gain both in this way. That a planet may be
gravitationally unable to hold gases in the long term, does not necessarily
disqualify it from being made livable on our time scales. The moon, for
example, would only hold air pressure for 4000 years; so? Refreshing the
pressure with another ice ball, every millenium or so, we could live with.
In contrast to carefully reasoned schemes to restore the Martian atmosphere
(from its rocks) over centuries, we will probably implement the plan which
will do the job in twenty, noisy, minutes. By guaging the impact velocity of
the ice ball, you can leave the planet with a new mountain of crushed ice, a
new atmosphere of water vapor, and a brisk planetary wash job with a shallow
flood, to scour away the salts on its surface.
For cracking off water's excess hydrogen to let it escape, a high flux of
ultraviolet is convenient in this job. From the start, the steam at the
lowest level will be relatively enriched in oxygen, and depleted in
hydrogen. This will allow high productivity (aerobic photosynthesizing)
microbes to thrive immediately at the surface. This instant biosphere will
be limited by carbon availability, not water nor air. To rush things, we
might design the initial greenhouse effect, so the climate for the first few
decades stays around the cozy 37 degrees Celsius, of the incubator.
Don't know if this should be mentioned, but if a planet's surface really has
a carbon shortage, there's lots of it around, in free space rocks. For
nitrogen, though, you have to find it a long way out, where it stays really
cold. Ammonia can be found (as an ice) anywhere uphill of Saturn. (It makes
more sense to bring in reduced nitrogen, which plants can use immediately,
than the element, which costs energy to fix.) I won't bring in any dynamic
considerations of impact engineering, at this point, or somebody will ask me
for numbers. The numbers, after all, are the whole project.
I will mention an intuitive suspicion, that somewhere within the
consideration of impacting bodies, lies a solution by which we could adjust
the rotational parameter of large bodies, without catastrophe to their
orbits. Mars doesn't need that treatment; it has a perfect length day for
Earthly plants. Further deponent saith not.