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Re: starship-design: Ice Impact Terraforming

> >  > See, you can't trick me into saying what I didn't want to mention,
> about
> >  > what I might have in mind for the Moon!
> Steve asks:
> > Would that be because it would sound dangerously like the plot synopsis
> > for "Space: 1999"?
> Did they want to spin up the moon's rotation 28-fold, to give it a 24-hour
> day?

Ah. My bro' reminds me "Space - 1999" was the TV series abaout a runaway
moon, actually used as a planetoid type starship. Flying around in a rogue
moon has never attracted me. Seems kind of extreme, an admission that the
starship problem can't be solved. I think otherwise, obviously.

The closest I have ever come to imagining the use of a moonlet vehicle, was
when I recommended that an ice body (moonlet) might be the substance of a
space ship. That was a matter of shielding, largely, and of using the ice as
reaction mass.  No tanks needed, when your "fuel" is a solid. This design
reflected an "inexhaustable" energy criterion. Ice ships are heavy, not as
much so as stony ships. But depending on how intense the radiation
environment becomes, the need for shielding might turn out to be a greatly
underestimated design parameter.

At a guess, I don't think a few feet of lead shielding will ever be enough
to let healthy humans approach the neighborhood of Jupiter, for example,
particularly the Io torus. Cosmic rays, defined as near-relativistic metal
nuclei, are the nastiest kind of hot. But when we start talking starships,
the forward direction gets really hot in this way, as the speed of light is
approached. I don't know any better answer, than to stick a lot of mass,
taking up a lot of room, both before and behind the starship. Ice is about
the cheapest bulky mass. Unless we have a breakthrough in the field of
radiation shielding, my approach is to err on the side of caution, then
double it, making all that cheap ice suddenly become very expensive.

About the Moon, though. At the pool table, I have seen collisions set the
three ball spinning rapidly, standing stock still on the table. I think
there probably are collision solutions which will drastically affect the
rotation of a large body, without appreciable damage to its orbit. The more
conservative approach is to use multiple controlled strikes, tangentially at
the equator, to spin up a body. A balance should be struck, between
collisions which would increase the orbital velocity, approaching from
behind in the orbit, and those which would slow the orbit by coming from
ahead. And, no, I haven't calculated how much energy it would take, to spin
up the Moon enough to make trees happy. Lots, huh?

Johnny Thunderbird