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From: fcrary@lightning.Berkeley.EDU (Frank Crary)
Newsgroups: sci.space,sci.space.shuttle
Subject: Re: space news from March 18 AW&ST
Message-ID: <1991May22.074255.3067@agate.berkeley.edu>
Date: 22 May 91 07:42:55 GMT
References: <1991May18.231158.24883@milton.u.washington.edu> <1991May20.034518.6909@agate.berkeley.edu> <1991May21.192557.12347@m.cs.uiuc.edu>
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In article <1991May21.192557.12347@m.cs.uiuc.edu> carroll@cs.uiuc.edu (Alan M. Carroll) writes:
>I'm missing this. The fast orbit takes a total of 34 months, or
>roughly 1020 days. That's too long, but a 1000 day mission isn't?

I should have been more exact. The stay on the surface is too long. Either
transfer orbit will result in long stay on the surface. In the case of a
minimum energy transfer, 400 days or so. The "fast" orbit could give you
a stay of 700 - 800 days. However, the "fast" orbit requires MUCH more
fuel. A "fast" mission could only land a limited amount of equipment. Not
enough for 26 months of surface exploration. Spending only 400 days, with
the equipment needed to do a good, detailed job of exploring is much more
effective. In general, "fast" missions are suggested to shorten the trip:
The fuel costs are almost prohibitive, but if you HAVE to return in less
than one year, this is the only way. A "fast" mission that waits on the
surface for the next launch window (26 months) does not do this, but still
has to pay the price in fuel.

					   Frank Crary
					   UC Berkeley