Space & Astronomy/Space and Astronomy (October 1993).iso/pc/text/spacedig/v16_3/v16no370.txt

Internet Message Format | 1993-07-13 | 33KB

Date: Fri, 26 Mar 93 05:44:54
From: Space Digest maintainer <[e-mail]>
Reply-To: [e-mail]
Subject: Space Digest V16 #370
To: Space Digest Readers
Precedence: bulk


Space Digest                Fri, 26 Mar 93       Volume 16 : Issue 370

Today's Topics:
                           Aurora spotted ?
                            Craf's Budget
                                 DC-X
                             Flame Derby
               Flame Derby (was Re: Luddites in space)
             Flight time comparison: Voyager vs. Gallileo
                        How long to cool Venus
                          How to cool Venus
                          Life in the Galaxy
                      Magellan Update - 03/22/93
       Play the Hat Game (was Re: Goldin's comment on Station)
     Predicting gravity wave quantization & Cosmic Noise (2 msgs)
                Robots, intelligence, and luddites :-)
                     SR-71 Maiden Science Flight
   Stockman, Mark, and Keyworth (was Re: Flight time comparison...)
                STS-55 (Columbia) abort (was Aurora?)
                      temperature of Lunar soil
                           Understatements
                  Why use AC at 20kHz for SSF power

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----------------------------------------------------------------------

Date: 25 Mar 93 22:38:08 GMT
From: Dillon Pyron <[e-mail]>
Subject: Aurora spotted ?
Newsgroups: sci.space

In article <[e-mail]>, [e-mail] writes:
>>For example, the SR-71 flying at Mach 3+/85,000 ft. normally took
>>about 200 miles to decelerate/decend when coming in for a landing.
>>Dean Adams (Tue, 23 Mar 93 07:17:28 GMT):
>
>From Mach 3.5 to speed 0 across 200 miles => mean deceleration a
>little less than 0.2 g. Is this a good performance ? How does work
>the SR-71 used by the NASA ?

Sudden and rapid decelleration and descent are unhealthy for aircraft.  You
need to allow for airframe cooling and to avoid shock cooling of the engines.
There is also a danger of flameout if you just pull the throttle back to idle.

>
>>> "Airquakes" seem not pleasant. (J. Pharabod)
>>It does not seem to be that much of a problem. (D. Adams)
>
>Why then these articles in the Los Angeles Times and Los Angeles
>Daily News? It seems that many people were afraid of a possible
>earthquake. And if there were a real earthquake, wouldn't some
>people stay home saying "that's just Aurora"?

Trying living in LA for a year.  Earthquakes are not some rare occurance.  The
only thing of note was that the seismologists were saying that there was
nothing in the ground to cause that.  If they hadn't said anything, no one
would have taken much notice.  I went through 6 quakes in one year.  Even had
one of my glasses break when it popped off a counter.

--
Dillon Pyron                      | The opinions expressed are those of the
TI/DSEG Lewisville VAX Support    | sender unless otherwise stated.
[phone] (when I'm here)     |
[phone] (when I'm home)     |God gave us weather so we wouldn't complain
[e-mail]          |about other things.
PADI DM-54909                     |

------------------------------

Date: Thu, 25 Mar 93 19:10:56 EST
From: Tom <[e-mail]>
Subject: Craf's Budget

>>>CRAF was cancelled because it had overrun its budget massively, and Congress
>>>was giving clear signals that this would not be tolerated.  This had nothing
>>>to do with the manned/unmanned wars.
>
>>I have a quibble:  FRED has overrun it's budget, but it lives.  Why the
>>'selective prosecution', if it's not about manned/unmanned, or at least
>>an effect of un/manned?

>Because Congress gave CRAF/Cassini an absolute total overall budget cap
>(with the stipulation that CRAF died first if there were overruns),
>something that has not been done for most other projects, including Fred.

>Few NASA projects, manned or unmanned, would survive to fly if they had
>firm budget limits.  Overruns are a way of life for NASA space projects.

So why the change?  When you say 'congress', do you mean all of them, for
this particular project, suddenly got fiscally concious, only to forget the
whole discipline thing for the next project that came down the pike?  Or
were there particular people, in Congress or NASA, say, that had an
attitude or an axe to grind, or what?  Surely there is more to this kind
of uncharacteristic behavior than just whim.  Any ideas?

Or was this just a year that congress got tight-wad, and CRAF was chosen
by people at NASA when the cut-or-lose-funding ultimatum was delivered?

-Tommy Mac
-------------------------------------------------------------------------
Tom McWilliams | 517-355-2178 (work) \\     Inhale to the Chief!
[e-mail]  | 336-9591 (hm)\\  Zonker Harris in 1996!
-------------------------------------------------------------------------

------------------------------

Date: Wed, 24 Mar 93 22:39:51 CST
From: "Norman P. Paterson" <[e-mail]>
Subject: DC-X
Newsgroups: sci.space

John R. Manuel <[e-mail]> writes:

> In article I write:
>
> >Are there any articles in Aviation Week, or somewhere similar, about DC-X
> >that someone can refer me to? I'm curious to see the design of the thing
> >and in particular, how it will manage re-entry and still be re-usable.
>
> I've got a bit more information about DC-X (thanks everyone for the
> pointers), but I still have my question about re-entry: how is DC-Y*
> going to be able to re-enter the atmosphere without experiencing engine
> damage? If it assumes an Apollo-like attitude on re-entry, I'd think that
> there would be a lot of ablative damage to the engines. What do the
> designers plan to do to prevent such damage and still make DC-Y
> immediately reuseable?
>
> * - Apparently DC-X isn't intended to go any higher than a few tens of
>     thousands of feet so it won't experience the worst effects of re-entry.
>
> ---------------------------------------------------------------------------
> John R. Manuel                                     [e-mail]
> 64-4-570-4024 (office)                           NIWAR Atmospheric Division
> 64-4-566-6166 (fax)                                 Wellington, New Zealand
> ---------------------------------------------------------------------------

According to my limited knowledge, DCX is only to fly within the
atmosphere - it is a testbed for a VERY much larger version which will be
a space truck - a replacement for the Shuttle.

[e-mail]
The Inquiring Mind BBS, Winnipeg, Manitoba  204 488-1607

------------------------------

Date: Thu, 25 Mar 93 20:10:56 EST
From: Tom <[e-mail]>
Subject: Flame Derby

Geo. Wm. Herbert suggests;
> Nick: hold your breath for a minute and don't post anything tomorrow.
> Dennis: hold your breath for a minute and don't post anything tomorrow.

> You two are both smart enough not to have to get into flame wars every
> few months...

Bill Higgins responds;
>Maybe they should both take a break and gang up on Allen.

Huh?  I'm confused.  I can't keep track of the interwoven web of harmonious
and divergent ideologies referred to here.  Maybe we could save a whole
lot of bandwidth and time if we could get a statement from each of our
potential contenders on the things they won't budge on.  Y'know, Nick could
tell us what he thinks, then Allen, Pat, et. al, followed by ONE rebuttal
each, explaining why they disagree or agree with each in turn.  Then, since
each contender had had their  say about each other, all this back and forth
would end.    NOT!

If anyone starts this, I say give points for enjoyability of reading, like
humor, flow, clarity, rather than 'winnable' points, like volume, logic, or,
God forbid, facts.  If we aim for audience enjoyment, at least the exercise
would have some redeeming value. :-)

Bill again;
>What do you think, George, are pat and Steinn promising new contenders
>in the Flame Derby?

Well, Pat, yes, but I'd have to go with Fred McCall over Steinn :-)
Sorry Steinn.

-Tommy Mac
-------------------------------------------------------------------------
Tom McWilliams | 517-355-2178 (work) \\     Inhale to the Chief!
[e-mail]  | 336-9591 (hm)\\  Zonker Harris in 1996!
-------------------------------------------------------------------------

------------------------------

Date: 25 Mar 93 22:40:38 GMT
From: Brad Whitehurst <[e-mail]>
Subject: Flame Derby (was Re: Luddites in space)
Newsgroups: sci.space,talk.politics.space

In article <[e-mail]> [e-mail] (fred j mccall 575-3539) writes:
>In <1or2vi$[e-mail]> [e-mail] (Pat) writes:
[etc.]
>>|   What do you think, George, are pat and Steinn promising new contenders
>>|   in the Flame Derby?
>>|
>>|Eek, and here I've been holding my breath for a whole day now!
>>|Definitely time to stop - no point anyway, I can never equal the
>>|ideological purity of previous champions ;-)
>>|
>>I'll have to agree with Stein.  Neither of us even vaguely come
>>close to Dennis or Nick,  although, I may be close to fred :-)
>
>No, Pat; you're clearly in the lead.  I generally only flame back; you
>seem to be self-starting.
>
    Hmm, so maybe the pair is hypergolic?  :-)

--

Brad Whitehurst    |   Aerospace Research Lab
[e-mail] |   We like it hot...and fast.

------------------------------

Date: 25 Mar 93 17:41:00 GMT
From: Eric H Seale <[e-mail]>
Subject: Flight time comparison: Voyager vs. Gallileo
Newsgroups: sci.space

[e-mail] (Dave Michelson) writes:
>In article <[e-mail]> [e-mail] (William Reiken) writes:
>>>
>>> A dearth of funding for planetary science didn't help much either.  As I
>>> recall, Reagan's "Science Advisor" recommended cancelling ALL funding
>>>
>>
>>    Can you please give a name for this quy.
>
>According to the account given by Bruce Murray in "Journey into Space", the
>man with the black hat (and the secret "Black Book") was Reagan's budget
>director, David Stockman.
>
>Apparently Stockman's "hit list" included the American part of the Inter-
>national Solar Polar Mission (the European part was later named Ulysses),
>the Venus Orbiting Imaging Radar (scaled back to the Venus Radar Mapper,
>later named Magellan), Shuttle-Centaur (which wasn't finally cancelled
>until after the 51L accident) and, by September 1981, NASA's entire
>solar system exploration program.  Only deft maneuvering saved Galileo
>and, ultimately, JPL.  Only the Shuttle was off limits to Stockman's axe
>because of its importance to National Security.
>
>George Keyworth, Reagan's science advisor, was apparently a good friend
>to Science in general but lacked the influence enjoyed by either his
>predecessors or his colleagues.

I guess I haven't used those particular neurons in a while... :-)   I
could have sworn I remembered some off-the-cuff remark by Keyworth (in
his earlier days) to the effect that space exploration was a "waste" of
funds "better" spent on SDIO (grrrr...).  Musta' been Stockman.  I'll
have to pick up the book so I can recover that part of my brain.

Eric Seale
#include <disclaimer.std>

------------------------------

Date: 25 Mar 93 17:07:49 GMT
From: Del Cotter <[e-mail]>
Subject: How long to cool Venus
Newsgroups: sci.space

[e-mail] (James Davis Nicoll) writes:

>    Could one of the thermodynamics-literate people on the net make
>a guesstimate as to how long it would take for the the Venerian  atmosphere to
>cool enough  so that the various components of the atmosphere liquified/
>solidified, given a sudden lack of illumination from the sun? I have a
>gut feeling it would take an inconvenient amount of time for Venus to
>cool, but I trust math over gut feelings.

I tried it once, and got between 200 and 2000 years to snow out the CO2,
depending on the assumptions about emissivity, heat capacity, latent
heat, and so on.  Several other factors need to be taken into consideration,
not least convection, but I *think* (ICBW) that 2000 years could be taken
as an upper bound.

Even so, it's a surprisingly short time.

BTW, I think the idea of snowing out Venus was Dyson's idea originally, and
Freitas wrote a paper suggesting:

    Snow out CO2
    Ship out CO2 as blocks
    Warm up again and terraform

but I haven't got the references here.
--
 ',' ' ',','  |                                                  |  ',' ' ',','
   ', ,','    |       Del Cotter       [e-mail]      |    ', ,','
     ','      |                                                  |      ','

------------------------------

Date: 25 Mar 93 13:56:10 GMT
From: Gary Coffman <ke4zv!gary>
Subject: How to cool Venus
Newsgroups: sci.space

In article <[e-mail]> [e-mail] (Paul Dietz) writes:
>In article <[e-mail]> [e-mail] (Gary Coffman) writes:
>
> > I think you're wrong about this, in practice if not in principle.
> > And I'd point to the same Soviet test as a counter argument. It's
> > been reported that the Soviet test was intended to be a 100 MT
> > device, but that their hydrocodes weren't advanced enough to
> > allow them to make a bomb that big that wouldn't disassemble
> > itself prematurely.
>
>And what *I've* heard is that they did not wrap a U-238 blanket around
>that device (which would have boosted the yield to 100 MT), perhaps
>because they didn't want that much fallout.  Dissassembly is
>less of a problem in larger devices, since the time it takes
>to dissassemble increases with device size.

Note that a U238 blanket wouldn't be to prevent disassembly. It's
to tap *fission* energy from the U238 fast fissioned by the high
neutron flux from the fusion core. That's a fission->fusion->fission
device.

>  > Of course a star is a perfect counterexample
>  > as well. Fusion only occurs in the core areas where both compression
>  > and temperature are extremely high. Trying for an intermediate
>  > yield, between the Soviet bomb and the Sun, presents formidable
>  > technical challenges.
>
>Actually, the history of the development of thermonuclear weapons
>is that big ones were developed first.  The first one, a bulky
>device using liquid deuterium/tritium, achieved 10 MT;  the first
>"dry" bomb with Li6-D achieved 15 MT.  Only later were the devices
>made smaller, prompted in part by the need for smaller reentry
>vehicles for increasingly accurate MIRVed missiles.

Well big computers came first too. I think that's mostly a matter
of technical prowess and not fundamental limitations.

>Laser fusion targets are to achieve yields of about 1 ton of TNT, with
>about .01 tons of driver energy, with core densities around 1000x
>normal.  Therefore, yields of about 1 MT with a 10 kT driver would
>naively require no compression (in practice, driving with a bomb is
>different from driving with lasers, so some compression is required
>here).  But clearly going to still larger bombs gives more slack, as
>the fuel density stays constant.  And we know we can build > 10 MT
>drivers, so there's three orders of magnitude of slack to play with.

I don't think I understand any of this. Laser fusion is supposed to
work by heating the target via compression. The two effects are
completely intertwined. I don't see how you're going to heat the
material without compressing it. What's to prevent an isothermal
expansion if the target material isn't constrained by compression?

My understanding of nuclear explosives is that the fundamental
problem is to prevent the device from dissassembling before
sufficient captures occur.

Gary

--
Gary Coffman KE4ZV          |    You make it,     | gatech!wa4mei!ke4zv!gary
Destructive Testing Systems |    we break it.     | uunet!rsiatl!ke4zv!gary
534 Shannon Way             |    Guaranteed!      | emory!kd4nc!ke4zv!gary
Lawrenceville, GA 30244     |                     |

------------------------------

Date: 25 Mar 1993 17:13:53 GMT
From: Carl J Lydick <[e-mail]>
Subject: Life in the Galaxy
Newsgroups: sci.space,alt.sci.planetary

In article <[e-mail]>, [e-mail] (Shari L Brooks) writes:
=
=In article <[e-mail]> [e-mail] writes:
=
=>From "Nature", Vol 362, 18 March 1993 (p. 204):
=
=> With these twin conditions, the authors estimate the size of
=>habitable zones around various types of star (fortunately, Venus and Mars
=>fall outside the limits for the Sun).
=
=why is this fortunate, somebody tell me.

Because if Venus and Mars fell within the range, the article wouldn't've been
published.
--------------------------------------------------------------------------------
Carl J Lydick | INTERnet: [e-mail] | NSI/HEPnet: SOL1::CARL

Disclaimer:  Hey, I understand VAXen and VMS.  That's what I get paid for.  My
understanding of astronomy is purely at the amateur level (or below).  So
unless what I'm saying is directly related to VAX/VMS, don't hold me or my
organization responsible for it.  If it IS related to VAX/VMS, you can try to
hold me responsible for it, but my organization had nothing to do with it.

------------------------------

Date: 25 Mar 93 13:33:43 GMT
From: Pat <[e-mail]>
Subject: Magellan Update - 03/22/93
Newsgroups: sci.space,sci.astro,alt.sci.planetary

In article <[e-mail]> [e-mail] writes:
|In article <1onp5v$[e-mail]> [e-mail] (Pat) writes:
|> How long will Magellan funding last, now that the conversion has been
|> made to the LMGT? And once the gravity data is collected after the
|> aero-braking exercise, is their any hope of collecting further radar
|> data, or does it look like the transmitters are pretty much shot.
|
|I think that Magellan project science support is due to expire at
|the end of September, although a NASA-sponsored "Venus Data Analysis
|Program" will taken over, so Magellan data will continue to be studied
|for years to come. The experiment has already generated about 400
|Gbytes of imagery and 10 Gbytes of altimetry.
|
|The degradation in down-link performance has been progressive. The
|last wide-band radar telemetry sent back in September 1992 was only
|partially readable, and even this was only made possible by heating
|the transmitter to the limit of its thermal tolerance. The target
|area (large volcanos named Hathor, Innini, and Ushas) hadn't yet
|been imaged by Magellan, so this high-temperature operation was
|adjudged worth the risk of melting something!
|
|No wide-band telemetry is needed for aero-braking or gravity mapping.
|While there is no lack of hope in this business, the odds seem to be
|stacked against receiving any more radar data.
|
|Peter Ford
|MIT Center for Space Research
|


Now, the rest of the next cycle is going to be eaten up
by aero-braking and the gravity mapping mission,  but
if they can get teh transmitters running, it'd be
nice to try and get some more detailed radar data, but from what you say,
it looks like the radar has just about had it.

oh well.  but on the other hand, the mission has already
exceeded the nominal mission profile by about 4 times.

pat

------------------------------

Date: Thu, 25 Mar 1993 15:48:00 GMT
From: Barry Schlesinger <[e-mail]>
Subject: Play the Hat Game (was Re: Goldin's comment on Station)
Newsgroups: sci.space

In article <1ons6r$[e-mail]>, [e-mail] (Pat) writes...
>In article <[e-mail]> [e-mail] (Bill Higgins-- Beam Jockey) writes:
>|
>|Goldin's speech suggests a whole new parlor game: Trying to imagine what
>|these hats look like.
>|
What this hat question brings to my mind is what the NASA official
told the Thiokol people who were reluctant to launch Challenger -- to
take off their engineer's hat and put on their manager's hat.
                BMS

------------------------------

Date: 25 Mar 93 20:54:29 GMT
From: Matt McIrvin <[e-mail]>
Subject: Predicting gravity wave quantization & Cosmic Noise
Newsgroups: sci.space,sci.astro,sci.physics,alt.sci.planetary

[e-mail] (Gary Coffman) writes:

>Why would there be an amplitude change? The EM wave is transverse,
>the G wave is compressive.

Compressive?  I thought gravitational waves were transverse quadrupole
oscillations.  The oscillating tidal forces are transverse to the
direction of motion of the wave.
--
Matt McIrvin

------------------------------

Date: 25 Mar 1993 10:32 PST
From: SCOTT I CHASE <[e-mail]>
Subject: Predicting gravity wave quantization & Cosmic Noise
Newsgroups: sci.space,sci.astro,sci.physics,alt.sci.planetary

In article <[e-mail]>, [e-mail]. (Thomas E. Smith) writes...
>[e-mail] (Cameron Randale Bass) writes:
>>In article <[e-mail]> [e-mail] (Gary Coffman) writes:
>>>>But that brings up a point. What is the relativistic interaction between two
>>>>waves moving at light speed? How do they view eachother?
>>>
>>>I wish there were an easy way to pass drawings in this medium. It would
>>>make explanations so much simpler. First lets clear up some differences
>>>in terminology and conditions here. A gravity wave can be viewed, like
>>>a sound wave, as a compression wave in spacetime. It alternately compresses
>>>and stretches the fabric of space (hackneyed term) like a steel ball
>
>I don't think that it ever compresses space, only stretches.

Not only does it compress space, but it does so at the same time as it
stretches it in the perpendicular direction.  Gravity waves have spin 2,
which means that they produce quadrapole deformations of space.  In
one direction they stretch, and in the other direction they compress.

-Scott
--------------------
Scott I. Chase            "It is not a simple life to be a single cell,
[e-mail]         although I have no right to say so, having
                 been a single cell so long ago myself that I
                 have no memory at all of that stage of my
                 life." - Lewis Thomas

------------------------------

Date: 25 Mar 93 16:54:12 GMT
From: Henry Spencer <[e-mail]>
Subject: Robots, intelligence, and luddites :-)
Newsgroups: sci.space

In article <[e-mail]> [e-mail] (Shari L Brooks) writes:
>In this context, intelligence is the ability to analyse an unfamiliar
>situation and make a decision.  Wait.  No, that is intelligence in
>*any* situation...

Actually, what we really want is competence, which is not quite the same
thing.  Competence is the ability to get yourself out of trouble when
you get yourself into it.  It doesn't absolutely require intelligence,
if the environment is simple enough.  Unfortunately, planetary-surface
environments are not.
--
All work is one man's work.             | Henry Spencer @ U of Toronto Zoology
                    - Kipling           |  [e-mail]  utzoo!henry

------------------------------

Date: 25 Mar 93 10:48:02 -0600
From: Bill Higgins-- Beam Jockey <[e-mail]>
Subject: SR-71 Maiden Science Flight
Newsgroups: sci.space

In article <[e-mail]>, [e-mail] (Bob Combs) writes:
> And I think the public should have the opportunity for
> review of government programs.  There is too little
> accountability in the government in general.  Well,
> I better shut-up on this or people will start flaming
> me and telling me to take it to alt.gripe.government or
> something.

And nobody will *ever* offer you a ride on an SR-71...

Submarines, flying boats, robots, talking         Bill Higgins
pictures, radio, television, bouncing radar       Fermilab
vibrations off the moon, rocket ships, and        [e-mail]
atom-splitting-- all in our time.  But nobody     [e-mail]
has yet been able to figure out a music           SPAN:  43011::HIGGINS
holder for a marching piccolo player.
                     --Meredith Willson, 1948

------------------------------

Date: 25 Mar 93 22:23:13 GMT
From: "John S. Neff" <[e-mail]>
Subject: Stockman, Mark, and Keyworth (was Re: Flight time comparison...)
Newsgroups: sci.space

In article <[e-mail]> [e-mail] (Dave Michelson) writes:
>From: [e-mail] (Dave Michelson)
>Subject: Stockman, Mark, and Keyworth (was Re: Flight time comparison...)
>Date: Thu, 25 Mar 1993 21:25:42 GMT
>In article <[e-mail]> [e-mail] (Eric H Seale) writes:
>>>
>>>George Keyworth, Reagan's science advisor, was apparently a good friend
>>>to Science in general but lacked the influence enjoyed by either his
>>>predecessors or his colleagues.
>>
>>I guess I haven't used those particular neurons in a while... :-)   I
>>could have sworn I remembered some off-the-cuff remark by Keyworth (in
>>his earlier days) to the effect that space exploration was a "waste" of
>>funds "better" spent on SDIO (grrrr...).  Musta' been Stockman.  I'll
>>have to pick up the book so I can recover that part of my brain.
>
>There is no doubt that Keyworth was a big fan of SDIO, but he was also
>a strong promoter of the Hubble Space Telescope and Shuttle-based astronomy
>(like the Astro mission flown last year).  Privately, he wasn't a big fan of
>JPL but then he was from LANL :-)  Notice that I only said he was "a good
>friend to Science in general".
>
>The real bad guys were David Stockman (the man with the Black Book) and
>Hans Mark (the man with the Blue Hat).
>
>---
>Dave Michelson                             University of British Columbia
>[e-mail]                                  Antenna Laboratory

In the book "The Power Game" by Kedrick Smith he tells how SDIO came about.
According to McFarlane and Keyworth and others, Pres. Reagan wanted
to prevent leaks and had the staff of the National Secruity Council
do the draft the SDI speech. Keyworth was brought into the loop by McFarlane
to provide scientific support. Keyworth felt at that stage all he could
do was engage in damage control.  I realize that this could be just
self serving BS on the part of Keyworth, but I don't think it was because
of his subsequent actions and speeches.

------------------------------

Date: 25 Mar 93 16:50:35 GMT
From: Henry Spencer <[e-mail]>
Subject: STS-55 (Columbia) abort (was Aurora?)
Newsgroups: sci.space

In article <[e-mail]> [e-mail] (Gary Coffman) writes:
>... So liquid or solid, once you light the
>boosters, you're committed to getting enough altitude to do a RTLS. The
>holddowns can't keep the Shuttle on the pad against both main engines and
>boosters.

There's no good reason why they couldn't.  The Saturn V holddowns could,
and did.  And they didn't even use pyrotechnic release -- they were 100%
mechanical.
--
All work is one man's work.             | Henry Spencer @ U of Toronto Zoology
                    - Kipling           |  [e-mail]  utzoo!henry

------------------------------

Date: 25 Mar 93 10:41:57 CST
From: Greg Titus <[e-mail]>
Subject: temperature of Lunar soil
Newsgroups: sci.space

In article <[e-mail]> [e-mail] (Henry Spencer) writes:
>In article <[e-mail]> [e-mail] (Russ Brown) writes:
>>>(This is why we can separate day-night variation from steady-state
>>>temperature.  The day-night variation is zero at the depths in question.)
>>
>>The measurements above 1.5 m were subject to the constantly changing
>>surface conditions.
>
>You're overestimating this greatly.  The temperature variation at a
>depth of 0.5m is only a few degrees, and it tapers off to zero at
>maybe 0.8m.  ...
>The regolith is a *really* good insulator.

Think of it as a rammed-earth wall with somewhat more than 1000 miles
of concrete behind it for thermal mass.   ;-)

greg
--
--------------------------------------------------------------
Greg Titus ([e-mail])                   Compiler Group
Cray Research, Inc.                               Santa Fe, NM
Opinions expressed herein (such as they are) are purely my own.

------------------------------

Date: Thu, 25 Mar 93 19:58:59 EST
From: Tom <[e-mail]>
Subject: Understatements

Gary Coffman sez;
> Trying for an intermediate yield, between the Soviet bomb and the Sun,
>presents formidable technical challenges.

        James Nicoll comments:
>       Now, that's sig.file fodder.

Sounds like the answer I heard to the claim that space colonization was
a moribund idea, since it came from the same drive the hurt vast numbers
of indigenous cultures and entire ecologies:

"But space is not like a continent.  There is somewhat more than a lot of it."

Sorry, forgot who said it.

-Tommy Mac
-------------------------------------------------------------------------
Tom McWilliams | 517-355-2178 (work) \\     Inhale to the Chief!
[e-mail]  | 336-9591 (hm)\\  Zonker Harris in 1996!
-------------------------------------------------------------------------

------------------------------

Date: 25 Mar 93 17:30:00 PST
From: "RWTMS2::MUNIZB" <[e-mail]>
Subject: Why use AC at 20kHz for SSF power

On 23 Mar 1993 15:25:37 -0500, Pat <[e-mail]> writes:

/Boeings revenues. are probably not more then 15 billion,  but
/they are now sharing that market with Lockheed, McDac, Airbus......
/
/The COmmercial aviation market is probably 100 Billion.

Aviation Week, 15 March 1993, chart on p. 61: total dolar sales of
U.S.-manufactured fixed-wing aircraft over 33 klb, including exports
=~ $35 billion (1992), estimate for 1994 =~ $30 B.

Ibid., chart on p. 65: total large transport sales worldwide =~ $60 B (1992),
(1994 estimate =~ $50 B.)

Ibid., p. 73: estimate for next 20 years, ~ 13,000 new transports worth up
to $1 trillion.

/PS.  Aviation is a fairly large segment of the US economy.  Larger
/then you think.   Dallas, Wichita, Seattle and St Louis make
/aircraft a substantial part of their business.

Agreed.

Ibid., p. 38: total U.S. 1993 aerospace sales = $100 B (2/3rds of total market).

Ibid., chart on p. 38: 1992 global aerospace sales =~ $50 B military aircraft,
$15 B missiles, $10 B military space, $ 60 B civil aviation, $ 8 B civil space;
total =~ 150 B. (declines to 1996, then increases).

(yes, I know that doesn't add up but the scale of the graph is small, and I
cheated on civil space - see next line).

of special note: Ibid., p. 38: estimated growth in civil space manufacturing
of 40 % between 1991 and 2000 (up to $13 B), not including the ground-bases
segment equipment.

BTW, I've seen it said in various places that the aerospace industry is the
largest single contributor to a positive balance of trade for the U. S.

Ibid., chart on p. 83: total U.S. 1993 aerospace exports = $45 B.

Does anyone have the import or net numbers, and any comparitive numbers between
aerospace and other industries, e.g. automobiles, consumer electronics, etc.?

Final related $ note: 1992 NASA's budget ~1/3 U.S. military space budget and
~ 2/3 1967 NASA budget in constant dollars [from memory, refernce may be
suspect :-) ]

Disclaimer: Opinions stated are solely my own (unless I change my mind).
Ben Muniz     [e-mail]    w(818)586-3578
Space Station Freedom:Rocketdyne/Rockwell:Structural Loads and Dynamics
   "Man will not fly for fifty years": Wilbur to Orville Wright, 1901

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From: Jeff Bytof <[e-mail]>
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Subject: 25 kg. to Venus, how much would it cost?
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Using existing technology and launch vehicles, what would be the
cheapest way to deliver a 25 kg. payload to the upper Venusian
atmosphere?

-rabjab

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End of Space Digest Volume 16 : Issue 370
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