The old "big rockets aexpensive" canard (was Saving energy is sil

Neither one of you is putting actual dollar numbers on the cost for
specific missions.

But Mike is dead on correct in saying that high delta v cost more. We
get around the impossibility of high delta V with low exhaust velocity
by staging.

I have proposed a really high exhaust velocity, up to 15,000 m/sec for
the second stage of a two stage to GEO vehicle with a liftoff payload
fraction of 1 in 12. (25 tons in 300)

An all chemical rocket would be 3 stages and have a liftoff payload
fraction of 1 in 60 (100 tons in 6000).

Making the stages reusable is yet another problem. The best proposal
I know of now is Reaction Engines Skylon. The structure in that case
is 50 tons out of 300. 16% is about the minimum if you want it to
have any fatigue life.

But as for a way to get regolith off the moon, it now looks like a
moving cable elevator out through L1 may be the best bet. It would
only take 45 MW to lift 100 tons per hr. And the stress on the cable
is low enough that current materials will work just fine. The payback
time is still being considered but looks short.

And using the elevator, we don't have to soft land anything on the moon.

Keith