Re: [MLUG - DISCUSSION] [POLITICS](and SCIENCE) NASA Plans Lunar Outpost

[Mike Miller <EMAIL:PROTECTED>]

On Tue, 5 Dec 2006, Stephen Montgomery-Smith wrote:

> Mike Miller wrote:
>
> > I'm surprised that they can mine hydrogen and oxygen from the lunar 
> > surface.  I hadn't heard that before.
>
> I found out about this a few days ago on the Discovery Science Channel. 
> There seems to be water on the poles of the moon, probably put there by 
> some meteorites crashing there.  The idea I guess is to use sunlight to 
> convert the water into hydrogen and oxygen.

Interesting.


> It seems to make planetary space travel on a regular basis feasible, in 
> that it makes the moon a good stopping point.  The energy required to 
> get objects out of earth's gravitational field are huge.  Apparently the 
> potential energy from the moon is a lot less.

Right.  An object on the moon ha 1/6 the weight of the same object on 
Earth.  It's also 250,000 miles closer to wherever we want to go (assuming 
we launch from the moon at the right time), but I would guess that the 
250,000 mile advantage is trivial compared to the gravity advantage.

So from Wikipedia, escape velocity on the lunar surface is 2.4 km/s and on 
the Earth's surface it is 11.2 km/s.  This is because the Earth weighs 
about 83 times as much as the Moon (5.9742×10^24 kg versus 7.3477×10^22 
kg), but the radius of the moon is 0.273 times that of Earth's radius. 
So the escape velocity on the Earth is about sqrt(83*0.273) = 4.7 times 
that on the moon.

http://en.wikipedia.org/wiki/Escape_velocity

Interestingly, from the lunar surface, the escape velocity to get away 
from the Sun (to leave the solar system) is about 42 km/s, and to escape 
Earth it is still 1.4 km/s (more than half that of the moon).  So to go to 
Mars one must deal with Earth, then the moon, but there is a constant 
strong pull from the Sun.

Mike

_______________________________________________
discussion mailing list
EMAIL:PROTECTED
http://mlug.missouri.edu/mailman/listinfo/discussion