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Mon, 6 May 91 01:31:25 -0400 (EDT)
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Date: Mon, 6 May 91 01:31:17 -0400 (EDT)
Subject: SPACE Digest V13 #489
SPACE Digest Volume 13 : Issue 489
Today's Topics:
United Space Federation, Update 5/1/91
Status of Space Station FAQ Response Effort
Re: Terraforming Mars? Why not Venus?
Re: Gas Guns and Tethers
Re: Terraforming Venus
GIF viewer
Re: Atlas Centaur bites the big one, 4/18
Re: Tethers
Re: Saturn V and Design Reuse: Saturn VI? (RBB: Real Big Booster)
Re: Tethers
Re: GREAT IDEA
Re: Galileo works?
Re: Terraforming Venus?
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In article <ce7711w163w@w-dnes.UUCP> waltdnes%w-dnes@torag.uucp writes:
>Theoretical problem 1) The centre-of-mass of the combined structure has
>instantaneously dropped closer to the earth's surface without the orbital
>velocity increasing. The result should be a lower orbit.
There are a variety of low-thrust high-exhaust-velocity propulsion systems
that are useless for boost from Earth's surface but are eminently suited
to slowly raising that orbit back up again. This does mean that some
fraction of your payload to orbit has to be fuel for the orbit-raising
system, but the high exhaust velocity means that the fraction is not 100%
or anywhere near it.
>As the shuttle climbs the tether, the space-station+tether descend a bit.
>Since we're dealing with a closed system, the centre-of-mass must remain
>in the same orbit.
In this case, the orbit lowering is temporary, because you return the
shuttle to the ground by reversing the process. (That also eliminates
the need to carry along fuel for retrofire.)
>Practical problem 1) Conservation of angular momentum... Unless the
>shuttle matches velocity *VERY* closely with the station, the two bodies
>will be spinning around each other at some horrendeous rpm's by the time
>the shuttle has climbed all the way up the tether.
The simple fix is just to make the station very much heavier than the
shuttle.
--
And the bean-counter replied, | Henry Spencer @ U of Toronto Zoology
"beans are more important". | henry@zoo.toronto.edu utzoo!henry
------------------------------
Date: 1 May 91 21:10:45 GMT
From: dog.ee.lbl.gov!hellgate.utah.edu!caen!math.lsa.umich.edu!zaphod.mps.ohio-state.edu!ub!ubvmsc.cc.buffalo.edu!v096my2q@ucbvax.Berkeley.EDU (Mark A Wieczorek)
Subject: Re: Terraforming Venus
In article <1991May1.173813.17587@en.ecn.purdue.edu>, irvine@en.ecn.purdue.edu (/dev/null) writes...
>
>I think Venus might be a bit easier to Terraform than Mars. With Mars, you
>have to find a way to add air pressure, with Venus, you have to find a
>way to decrease it (never minding the fact that both are poisonous
>right now ... :) )
>
>This could be an opportunity to try out bio-technology. Send a group of
>microbes that "eat" sulphur in sulphuric acid, cleaning the air.
Sending microbes to venus may help clean up the air, but I can't
imagine it having much of an effect on the atmospheric pressure or surface
temperature. Supposively, Venus, Mars and Earth at one time had the
same amount of water on the planet. Since venus receives about twice? as
much solar energy as Earth the water has vaporized which causes the
huge atmospheric pressure, while on mars it may be frozen out in the
polar caps and soil. I think the main issue here is to first heat up the
martian surface by throwing in some CFC's or something similar, or possibly
permanently shielding venus from the sun. After the atmosphere is
normalized by human standards then we can worry about wether or not it's
or not and how we would go about cleaning up that.
Also when people talk about bombarding either mars or venus with
comets. Where are they going to come from and how are they going to get here?
Is their any evidence that their actually is an oort cloud, or is this
just a nice hypothesis?
Mark Wieczorek
------------------------------
Date: 1 May 91 21:40:38 GMT
From: psuvm!gws102@psuvax1.cs.psu.edu
Subject: GIF viewer
Does anyone know where I can get a GIF viewer for a MAC, IBM, and/or UNIX works
tation. Information on any of these computer formates would be appreciated.
