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: 209.88.68.33 Message-ID: <9186edb5.0312080237.2e387357@posting.google.com> cfrjlr@yahoo.com (Charles F. Radley) wrote in message news:... > 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