In sci.space.policy Vincent Cate wrote:
(Terry Goodrich) wrote in message . com...
Please don't loose track that we are trying to just get 20 kilo or so
of moon rocks to sell to collectors, not mine the moon. While I can
see the value of developing tethers and ion drives for a long term
project (I have a lot of interest in ion and vasmir drives), I don't
believe we have a budjet for any heavy duty R&D ($400~500 million).

You might only want 20 kg, but some of us want more. I think people
would buy much more than 20 kg of moon rocks at a price that
permits a good profit if you use tethers. If you could get more
than 20 kg of diamonds, you would not want to?

Depending on whetever getting them would require going to an unkown
and anproven technology for which you not just can't really get
proven materials but also you need to do a many orders of magnitude
higher up-front investment. For initial profit based missions, tethers
simply don't enter into the picture.


Ion drives are standard options on GEO sats these days (and I
expect most use some kind of electric propulsion for station keeping).

I don't think it would cost $400 to $500 mil, but it is clearly
hard to say.

SMART-1 cost $100m. Its a small orbiter and was launched as a add-on
cargo on a flight where most of the expenditure was paid for by other
satellites. You are going to need the full capacity of a heavy launcher,
so $150 - $180m. Assuming that whatever you are launching cost you $200m
to develop and build is reasonable and you co-incidentialy have arrived
at $400m.


To me it seems much easier to justify an investment if you end up
with a low ongoing cost and 100 kg a month than a deal with a
onetime payback of 20 kg.

Really? have you tried writing this up? How much mass doyou need to launch
and how much does the thing launched cost? And please use realistic present
day costs and not arbitrarily tweaked numbers until it worked for you.


-- Vince

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Vincent Cate Space Tether Enthusiast
http://spacetethers.com/
Anguilla, East Caribbean http://offshore.ai/vince
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ~~~~~~~~~~~~~~~~~

You have to take life as it happens, but you should try to make it
happen the way you want to take it. - German Proverb

--
Sander

+++ Out of cheese error +++