Google Lunar X-Prize (was Re: NASA ESMD Lunar Architecture Update)

In article <59104$46fa52b3$927a2cda$1351@xxxxxxxx>,
"Jeff Findley" <jeff.findley@xxxxxxxxxxxxxx> wrote:

I'm a bit skeptical that it will be won. Landing on the moon is a lot
harder than what Spaceship One did. For one thing, Spaceship One had a
pilot on board who could compensate for unforeseen problems (same thing with
the Apollo 11 lunar landing). You won't have that with an unmanned lunar
lander.

True, but we have dramatically more computing horsepower available now
than we had in the Apollo 11 days. A pocket-sized computer can measure
altitude, calculate velocity and acceleration, project final position
and velocity, and adjust the thrusters thousands of times per second.
With no atmospheric effects to complicate things, this should be quite
straightforward. (Though granted, it'd be even easier if we had a lunar
version of GPS.)

There are only two complications I can think of, both related to coming
down in unfamiliar terrain:

1. You might come down on top of a boulder, and this would both add
noise to the altitude measurements, and if your design is insufficiently
robust, could screw up your lander. But look at the battlebots -- these
things routinely survive impacts from high-velocity kinetic weapons, and
can be flipped into pretty much any position without getting stuck. And
they're built in garages for a few thousand bucks. Landing on a boulder
shouldn't be a big problem.

2. If you still have significant horizontal velocity at low altitude,
you might smack into a rock that sticks up out of the terrain. This
could be avoided by careful surveying of the landing site (surely we
have better data now than in the Apollo days, right?), and by nulling
your horizontal velocity a bit higher up and dropping straight down. I
realize that this takes more fuel, but we're only talking about landing
something weighing 10 or 20 kg. The fuel requirements shouldn't be a
problem.

Spaceship One's job was difficult because it had to deal with
aerodynamic forces, which are complex, strong, and extremely difficult
to simulate. A spacecraft in a vacuum is much simpler.

Now, I will readily admit that putting all the needed off-the-shelf
parts together isn't trivial, and since there's no way to test it all on
Earth, you really want to get it right on the first try. That can be
tricky with any system; it's much easier to work the bugs out
iteratively. But with the size of the purse, I wouldn't be surprised if
somebody comes prepared to try 2 or 3 times if necessary. And that
should be enough. It's also quite possible that somebody will nail it
on their first try.

Best,
- Joe

--
"Polywell" fusion -- an approach to nuclear fusion that might actually work.
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