Vincent Cate wrote:

(Henry Spencer) wrote in message ...
In article ,
Vincent Cate wrote:
If you use an ion-drive to get to lunar orbit and back and a tether to
collect samples, you don't need to be so mass-limited in your design
and you could bring back much more lunar mass. The difficulty of having
the end of the tether pickup some samples seems much less than having
a couple more rocket stages...

However, the tether deployment, spin-up, and control are basically research
projects, whereas rocket stages are fairly well understood.

On the other hand there is not so much room for improvement in rockets.

There's not a lot of room for improvements in efficiency (Isp), but
we've barely scratched the surface as far as cost reduction is
concerned.

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