Message-ID: <8aBIAcW00VcJQLzE59@andrew.cmu.edu>
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To: space+@Andrew.CMU.EDU
Date: Wed, 25 Apr 90 02:26:49 -0400 (EDT)
Subject: SPACE Digest V11 #316

SPACE Digest                                     Volume 11 : Issue 316

Today's Topics:
			    Re: HST focus
		     Re: Dyson spheres, heat flow
	     Re: "Family Portrait" (Has anyone seen it?)
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Date: Tue, 24 Apr 90 10:34:40 EDT
From: John Roberts <roberts@cmr.ncsl.nist.gov>
Disclaimer: Opinions expressed are those of the sender
	and do not reflect NIST policy or agreement.
Subject: Re: HST focus


>From: swrinde!cs.utexas.edu!news-server.csri.toronto.edu!utgpu!utzoo!henry@ucsd.edu  (Henry Spencer)
>Subject: Re: NASA to brief media on Hubble Space Telescope instrument test

>...and to head off some more, it's in the constellation Carina, and there
>is no intrinsic interest in it -- that's just the direction HST will happen
>to be pointed at the time.  The image is not expected to reveal anything,
>except perhaps that more work is needed on focusing. :-)

The polymer frame that holds the HST optics contains a certain amount of 
water absorbed from the atmosphere. Once in space, it is expected to dry
out over the course of days or weeks, and as it dries, the frame will change
shape. Designers have tried to construct the frame so it will have an optimal
shape when fully dry and in 0g. In the meantime, it should still be usable
due to the range of motion provided by the actuators.
                John Roberts
                roberts@cmr.ncsl.nist.gov

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Date: 25 Apr 90 04:56:41 GMT
From: uokmax!spcoltri@apple.com  (Steven P Coltrin)
Subject: Re: Dyson spheres, heat flow

In article <9004242137.AA02290@cmr.ncsl.nist.gov> roberts@CMR.NCSL.NIST.GOV (John Roberts) writes:
>Additional question: in "Ringworld", Larry Niven describes a cooling system
>for use in a spaceship near a star - since cooling by radiation is impractical,
>the waste heat is pumped to a collection point within the ship, from which it
>will be dispensed when the ship is no longer near a star. Could this work, and
>if so to what extent? I could make a guess, but that's all it would be.

That would depend on how good your heat sink and pump (and insulation) were...
and how much risks you want to take.
A better system occurred to me awhile ago; presuming the _Lying Bastard_ was
fusion-powered (I don't remember if it was ever stated, even), then the power
plant is going to be producing helium exhaust.  Just pump your waste heat into
it and jettison.  Comments?

   --SPC
'Dammit, Jim, I'm a linguist, not an engineer!'

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Date: 23 Apr 90 17:44:46 GMT
From: att!cbnewsl!sw@ucbvax.Berkeley.EDU  (Stuart Warmink)
Subject: Re: "Family Portrait" (Has anyone seen it?)

> 	What happened to the "Family Portrait" (a photograph that would
> 	depict some planets of our solar system altogether) that was
> 	supposed to be taken by the Voyager 1?

As of last Friday, all images had been transmitted to Earth. However, one
series of images (a sequence of 10 or so in the inner-solar system region)
was lost because of rain at the receiving site. So...they were commanded
to be re-transmitted - but then a failure at the receiver (Pasadena?)
cause the images to be missed *again*! A third attempt was to be made
early this week (4/23), I understand.

The instrument was not damaged in the process of taking the images, and
all but Mercury and Pluto are visible (Pluto wasn't even attempted). From
what I gather, the rings of Saturn are even visible! (sort of, I guess).

Pictures will be released in various sizes, such as "outer planets" and
"inner planets", etc, right up to the full large-wall size mosaic, which
covers not only the planets, but also star fields in roughly straight
paths between the planets. The planets were imaged in colour, too.

The images will be released at the end of May (the 25th rings a bell?).
The NA&SM in DC will be one of two places with the full mosaic; I can't 
remember the other one.

I got this information "straight from the horse's mouth" at a JPL talk
about the Neptune encounter, at the National Acadamy of Science (?) in NY City.
Any possible deviations from reality are caused by memory errors on my part!
-- 
------------------------------------------------------------------------------
Stuart Warmink, Whippany, NJ, USA  |  sw@cbnewsl.ATT.COM  |       Hi!
-------------------------> My opinions are just that <------------------------

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End of SPACE Digest V11 #316
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