From: vince@offshore.ai (Vincent Cate)
Newsgroups: sci.space.tech
Subject: Re: Lunar Sample Return via Tether
References: <9186edb5.0312061749.206011fa@posting.google.com>
NNTP-Posting-Host: 207.42.133.230
Message-ID: <9186edb5.0312101309.4509af66@posting.google.com>

I am not sure how far you could scale this project down. I don't think 
it would be too hard to get by on the 1,300 lbs to LEO of Space-X.
I expect you could even get down to 500 lbs.  

At some smallness it gets hard to make fault tolerant tethers, but I 
am not sure where that is exactly.   I don't think space junk 
is nearly the issue around Luna as around Earth.  There has not been 
the human stuff smashing into each other and making lots of orbiting 
junk.  You can get fault tolerance by having spare tethers, as 
the tethers you need for the moon are not really too heavy.  You can 
make your tether shorter than 100 km, say 5 km, since the non-human 
payload can tolerate high Gs.  This also reduces the chance of collision.  
Very small diameter Spectra lines are available.  And if your last
tether did happen to break, you just head back to Earth with whatever
regolith you have so far.  So a very small tether is probably doable.

Scaling down solar power is easy.  You can get small Hall Thrusters.
At busek.com they have one that is just 900 grams.

It might really be possible to do this project in under 100 lbs,
though that would be impressive.

   -- Vince