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Re: starship-design: Ice Impact Terraforming

Roy Bennett writes,

Isn't it true that the same area of the Moon always faces
the Earth. IE it doesn't spin relative to Earth?


responding to my -->
> 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
> conservative approach is to use multiple controlled strikes, tangentially
> 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
> up the Moon enough to make trees happy. Lots, huh?

so I say,

The Moon spins once a month (its orbital period) relative to the sky. (No, I
won't mess with synodic and sidereal,  and stuff like that. Not until I'm
really ready to make the spin-up calculation.) We always see the same face
of the moon, because it is "tide locked" to us, as its gravitational
primary. That is a low-energy stable state, implying the Earth-Moon dynamic
system is very old. The Moon had a spin when it formed, but Earth's
gravitation just gradually wore down that smaller body's spin energy.

The tidal force that "locks" the Moon's rotation to Earth's center of mass,
is more a frictional force at high energies, but would be a temporary
impediment when the speed-up was just starting. That's when you have hit the
Moon's equator with just a few rocks. But after you have broken free of this
initial stasis, the tidal drag wouldn't be anything you'd have to worry
about, in the next few million. Fully established with a 24-hour day, you'd
see half a moon rotation from Earth's surface, if the Moon was above your
horizon for 12 hours. The next night, about the same, only 1/28th difference
in the Lunar scenery you saw the previous night. Every month (don't ask!)
you'd see everyplace on the Moon at your "lunar midnight" zenith. The phases
of the Moon would look the same as they do now, if you're nearsighted as me.

The surface of the Moon is the same as the land area of the continents. We
would not double the area of our productive forests and farms, though, by
terraforming the Moon. It would be necessary to cover about half of it with
seas, to ensure thermal stability in our new biosphere. So a 50% increase in
the room available to land life, is our outside limit. Every little bit
helps, if you're life trying to stay alive. Mars is the biggie, that's the
pie. We can't mess up on that one.

Venus is a long shot. You will hear it here first, by the way; I don't know
anybody else who might have made this suggestion. I keep imagining dynamic
solutions. I never try to pretend my imaginings are accurate, as
solutions to the relevant equations. For anybody who hates math as much as I
do, my fantasies will have to serve as a surrogate for accurate knowledge.
At least until I get some fancy computer programming done, to show that
machines are great tools, to keep us from having to do all that
uncomfortable thinking, in mathematical symbols. To me, programming is easy,
but math hurts.

Venus needs a radical treatment: we ought to blast its atmosphere off. The
oxidized gases which comprise it, are in low energy states. Entropy got
there first. We don't have any good energy leverage to use, to transform
those gases to less hostile molecules. CO2 and SO2 and H2O, man, you're
nowhere with those, chemically. Blast Venus with a comet, and start over on
the atmosphere building. More specifically, an exploded comet, scattered
bombwise just before impact, until its impact area covers an entire
of Venus. Comets are quick. We would need a big one. We would probably need
to go out in the Oort Cloud, to ship it in. That's a long trip. Meat and
potatoes for us.

An ice cloud which hits half of Venus, will serve an eviction notice to the
nastiest atmosphere in the system. Uncle Pow, and the near side gases are
pushed out to nowheresville. The noise gets around the planet pretty quick,
and at the nadir the atmosphere spews up in a great fountain. You might lose
2/3 of the gases at Venus escape velocity in this impact, possibly the best
we can hope for. Unless we decide to, umh, iterate, if we decide that even
1/3 of the CO2 of Venus, plus all the water vapor we just added, is still
too heavy. Am I serious?

Well, it would be a lot of work, terraforming Venus. We can't handle as much
CO2 as there is on Venus, with any known biological, chemical, or
geophysical processes. The only way to get rid of it is by violence. I
eagerly advocate impact terraforming. Let's go ahead and get this business
fixed, while we're still young enough to enjoy it. After Mars and the Moon,
Venus is the only real estate left in the habitable thermal zone. Farm land
is gold, to a humanity of large population. To expand after that, we have to
go the long way. The long way, is what our correspondence is about.

Johnny Thunderbird