(Charles F. Radley) wrote in message
. com...
Nice idea, but not original. Hoyt, Forward and Moravec have each
proposed using tethers for lunar landing and sample return some
years ago.

I realize that they proposed tethers for the Moon; however, I have
not seen them point out that you could pick up samples without any
infrastructure in place on the Moon. The thing that might be
original is that a single probe, with no advance landing on the moon,
could use a tether to scoop up samples.

It can be done even more cheaply than you propose.

You do not even need any ion drive or propulsion at all actually.
You can do it entirely with zero momentum exchange, you simply
deposit payloads on to the lunar surface whose mass equals that of
the samples you remove.

If we use an ion drive of 10,000 seconds ISP, it is throwing xenon
out the back at about 98 km/sec. To pick up something from the
Moon we need to give it 1.6 km/sec of momentum. So with the momentum
from 1 Kg of xenon we can pick up 98 kps / 1.6 kps or about 61 Kg
of regolith. If you simply deposited equal mass on the lunar surface
you would only pick up 1 Kg for every 1 Kg you put down. So this way
is cheaper for a probe on a sample return type mission.

For the details, take a look at these web links:

http://www.tethers.com/MXTethers3.html

http://www.tethers.com/MXTethers.html

When I say "lunar sample return" I mean that there is nothing already
in place on the Moon. I have not seen anything in these or any
others papers I have read that indicates they were thinking of a
sample return type mission. Sure people have looked at Lunar
tethers. And I do think that two way lunar tether traffic would be
*really cool*. In particular once we have lots of tourists going to
the moon and coming back.

-- Vince