Some thoughts on Mining Asteroids vs the Moon

Hi,

You have only mentioned the basics. A lunar and/or
Venus gravity assist can greatly reduce these delta-v
numbers. In fact with multiple fly-bys only a little
bit more than escape velocity is required to get out
there. Getting back is similar but in reverse order.

This fact is what makes the possibility of retrieving
a "chunk" of an asteroid more than just a fantasy. So
could we imagine sending out a robotic spacecraft,
with high specific impulse engines, to rendezvous with
a NEA, scoop up a good fraction of it (say 10%), then
use a tether to despin the NEA. This despin maneuver
could also impart a significant delta-v to the
spacecraft and its "chunk" (a bag of asteroidal
material). With just the right timing and
calculations, the spacecraft and its "chunk" would
sling around Venus and the moon and this very little
delta-v, be captured into a 2-month highly elliptical
lunar periodic orbit. From this orbit we could send
robotic and manned spacecraft to process that
material, whether it be for He3, Platinum group
metals, water, or whatever.

OK, this may take several years from launch, but it
should be relatively cheap. OK, it would certainly be
a high risk mission. But we could mitigate some of
the risk by sending out 3 or 4 similar spacecraft to 3
or 4 different targets, over a year or so. When we
see that one of the "chunks" is on their way to earth
orbit, we could invest in the processing equipment and
crew facilities.

What do you think, $200M for the 3 or 4 retrieval
Spacecraft? Maybe that much again to launch them to
escape velocity? I don't think it would be too hard
to raise the money to process the "chunk(s)", once
they were earth bound.

Dave