Space & Astronomy/Space and Astronomy (October 1993).iso/mac/TEXT/SPACEDIG/V12_4/V12_493.TXT

Internet Message Format | 1991-06-28 | 16KB

Return-path: <[e-mail]>
X-Andrew-Authenticated-as: 7997;andrew.cmu.edu;Ted Anderson
Received: from beak.andrew.cmu.edu via trymail for +dist+/afs/andrew.cmu.edu/usr11/tm2b/space/[e-mail] (->+dist+/afs/andrew.cmu.edu/usr11/tm2b/space/space.dl) (->ota+space.digests)
          ID </afs/andrew.cmu.edu/usr1/ota/Mailbox/Qb9yOfG00VcJE1Hk5r>;
          Fri, 26 Oct 1990 03:33:03 -0400 (EDT)
Message-ID: <[e-mail]>
Precedence: junk
Reply-To: [e-mail]
From: [e-mail]
To: [e-mail]
Date: Fri, 26 Oct 1990 03:31:27 -0400 (EDT)
Subject: SPACE Digest V12 #493

SPACE Digest                                     Volume 12 : Issue 493

Today's Topics:
              Re: Deep Lunar Dust Story?
              Re: Venus/Magellan, poles
       Re: You Can't Expect a Space Station to be Cheap
                 Re: Ulysses
            Re: Pioneer 11 article
              results of query on skills

Administrivia:

    Submissions to the SPACE Digest/sci.space should be mailed to
  [e-mail].  Other mail, esp. [un]subscription notices,
  should be sent to [e-mail], or, if urgent, to
             [e-mail]

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

Date: 23 Oct 90 10:49:27 GMT
From: mcsun!ukc!edcastle![e-mail]  (J Gillespie)
Subject: Re: Deep Lunar Dust Story?

[e-mail] (JOSEPH T CHEW) writes:

>Arthur C. Clarke, in his science writing, may have been a moondust skeptic
>as far back as the late  '40s, cf. an earlier posting, but, wearing his
>other hat as a science-FICTION writer, he milked the idea much longer.
>"A Fall of Moondust" (think of it as "The Posiedon Adventure" set in a
>lunar valley full of guess-what) came along in the early '60s, I believe.

>--Joe
>"Just another personal opinion from the People's Republic of Berkeley"

Another SF writer, Larry Niven, has used the deep dust idea wrt Mars,
but not the Moon, because (and I think most of this was written after
lunar landings, but before Mars landings), Mars has just enough atmosphere to
prevent vacuum cementing, but the Moon doesn't.  Vacuum cementing
apparently takes place when there are no adsorbed gases on the surfaces of two
solids in contact with one another to prevent them from bonding in some
unspecified way.  The bottom line is, fine dust in a vacuum becomes rock
pretty fast, but in just a little atmosphere will stay dusty.

On Niven's Mars, meteor dusty looked and acted like a thick, oily
liquid, and formed "oceans" in some places.

James Gillespie

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

Date: 23 Oct 90 18:47:31 GMT
From: usc!zaphod.mps.ohio-state.edu!mips!bridge2!3comvax![e-mail]  (Michael McNeil)
Subject: Re: Venus/Magellan, poles

In article <[e-mail]>
[e-mail] (Greg Macrae) writes:
>Mercury is tide locked with the sun.  That is one side always faces the sun.

Mercury is *not* tide locked with the sun.  Its rotation rate, 59 days
as I recall, is not at all the same as its revolution rate of 88 days.
Although it was thought for a long time (80 years or so) that Mercury
was tidal locked, its correct rotation has been known since the 60's.

--
Michael McNeil            [e-mail] (3comvax.UUCP)
3Com Corporation        ucbvax!hplabs!oliveb!3comvax!michaelm
Santa Clara, California        work telephone: [phone] x 5-208

    To be an Error & to be Cast out is a part of God's design.
        William Blake

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

Date: Wed, 24 Oct 90 20:32:28 -0400
From: "Allen W. Sherzer" <[e-mail]>
Subject: Re: You Can't Expect a Space Station to be Cheap
Newsgroups: sci.space
Cc:


In article <[e-mail]>
>Thanks for your assistance.   I would like to continue if you
>have time.

Glad to. I do however have a request: can you please single space
your replies? It makes them more readable. Thanks.

>Aha !  Ten years lifetime - that changes everything, do you have
>any idea how much cheaper Fred would be if it only had a ten year
>lifetime requirement ?   I do not have any numbers, but it is a
>whole new ball game !   Seems LNNL and co are talking apples
>versus oranges.....

I'm sure Freedom would be much cheaper with a ten year life time.
So what? I can launch a LLNL station every ten years for thirty
years for about 20% what Freedom costs. Of course I suspect we
will learn a lot about space stations in that ten years and
we may very well want something different. With LLNL we can change
the design if we want. With Freedom we will be stuck with it.

Another thing to remember is time to develop. If we began when
the idea was proposed, the first LLNL station would end it's
operational life before Freedom even begins its. A lot of science
isn't going to get done waiting for Freedom.

Now all other things being equal wouldn't we be better off using
the LLNL design and send a new one up every ten years?

>Note: atomic oxygen is not O2, it is O or AO.

Sorry. I just typed it in without thinking. You are of course correct.

>Rad-hard electronics generally makes use of expensive "limited
>edition" chips developed by the military.

Of course since LLNL is in the 'radiation buisness' being a DoE lab.
As I said NASA didn't list it as a problem so I assume they think
their approach is valid.

>+The LLNL Earth Station goes up in 1 HLV flight. This can be done
>+because  the inflatable structures greatly reduce weight and
>+launch volume.

>Aha again !   Another case of apples and oranges.

Why? If Freedom used expendables instead of insisting on using
the Shuttle their costs would also drop. At $500 to $900 a pop
those assembly costs add up fast. Why is that apples and oranges?

>Does LLNL figure in the cost of developing HLV in their costing ?

Does Freedom figure in the cost of developing the Shuttle in their
costing? Not only do they not figure in that cost, they also use
subsidized numbers.

The LLNL plan however, does figure both development and the true
operational cost. They have two qualified contractors
signed up to do it for a fixed fee. This HLV will cost less than
ONE shuttle flight to develop. It will lift twice what the Shuttle
lifts for a quater to half the launch costs.

>Seems kind of expensive to develop a whole new HLV then only fly it
>once.

Since it's development and operational costs are so far below the
Shuttle, it isn't expensive at all. In addition, doing it in one
launch with deployment in shirt sleves reduces risk. No EVA is required
for station construction.

Besides, they plan to fly it 20 times. Maybe somebody else can
also use it. However even at one use it will be far far cheaper
than using the Shuttle.

>Cheaper to use a smaller SSX and take it up in several peices.

Now *THAT'S* risky. The above HLV's are all based on existing
technology. Over 90% of the parts can be bought today. SSX
on the other hand requires a lot of new stuff. It would be
far more risky for LLNL to use SSX.

>+They are claiming 1KW per kilo of silicon. NASA says that is an
>+order of magnitude better than the state of the art. (Dr. Wood
>+provided them with samples).
>
>Samples alone mean little....

Fine. If it doesn't work they will use what does work. It won't
affect their schedule and will have only minor impact on cost
(1 to 2 million).

BTW, they do plan to qualify the cells in the three years they
need for design and HLV development.

>+Either way, this is a minor issue. The weight budget for power
>+is big enough to use what NASA says is the state of the art.

>Then why did they bother proposing amorphous Silicon ?

Because it will save the taxpayers a couple of million $$. I
think that's a great reason.

> >5 - LLNL's Nickel-hydrogen batteries are nothing new...

>+ Interesting. The NASA assessment says these batteries won't
>+work [3].  Why is Freedom using batteries which NASA says won't
>+work? If they will work, why is NASA saying they won't?

>Could be a design detail.   Maybe LLNL have some new exotic
>variant of NiH cells.

Nope. They are off the shelf.

>NiH cells are already in orbit on several spacecraft,

Which makes NASA's reaction even more strange.

> >6 - What experience does LLNL have in the following areas of
>> space applications:-

>+ Don't know in detail (why don't you call and ask?).

>Prefer to minimise my long distance calls.

Me too. I just figured since you are about 2000 miles closer... :-).

>Do you have e-mail address for anybody there ?

Don't have one. Anybody from LLNL reading this?

>Any of those guys coming to
>southern California any time soon ?

Invite them down.

> >The impression I have is that LNNL trades off safety and risk
>> versus cost.

>+ And who doesn't? The only way for Freedom to avoid those trade
>+ offs is to not build it.

>At first sight you can save an awful lot of money by accepting
>higher risks, but then again expensive spacecraft like Shuttles
>and Space Station, are very expensive and their replacement cost
>must be figured in the risk equation.

Quite correct. But then since the LLNL approach costs 5% as
much as the station and half the cost of a new orbiter and the
LLNL station has an ACRV, this risk is justified.

>+Tell me something, as a safety engineer on Freedom what are the
>+odds of a death due to a major breach of the habitation module?

>100 %, except for those wearing EVA suits.  Same for LLNL.

Of course the odds of anybody being in a breached module is lower
in the LLNL station. I would assume therefore that it is actually
safer in this respect.

>>There is nothing clever about taking risks, any fool can do
>> that.

>+That implies that the people flying on Freedom are either not
>+taking any risks or are fools.

>Foolishness is proportional to degree of risk taken.

Tell me, how much risk would you consider acceptable? Since the LLNL
is about as risky as Apollo, do you also think Apollo was a mistake?

>NASA keeps asking for assured crew return vehicle, congress keeps
>deleting it from the budget.

Given the cost of the NASA ACRV this comes as no suprise. Why
not just buy a Soyuz?

>As the cost of aerospace systems escalates, the tendency to "push
>the envelope" naturally falls off.

NASA's *JOB* is to push the envelope.

>The B-2 test program made little if any attempt to "push the
>envelope" in the Chuck Yeager sense.

Rest assured it will before it becomes operational.

   Allen

--
+-------------------------------------------------------------------------+
| Allen W. Sherzer      |         What should man do but dare?            |
|   [e-mail]         |             - Sir Gawain                        |
+-------------------------------------------------------------------------+

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

Date: 24 Oct 90 23:36:32 GMT
From: csusac!csuchico.edu!petunia!ucselx!crash!pro-canaveral.cts.com![e-mail]  (Ken Hollis)
Subject: Re: Ulysses

Greetings and Salutations:

>From: [e-mail] (Robert W Murphree)
>Subject: Ulysses
>
>Dear Ron Baalke:
>
>Could you comment, either by E-mail or in sci.space or sci.astro about the
>possibility of an extended mission for Ulyssess?  After 1995 comes and the
>south pole of the sun is past, what's to stop Ulyssess from making the
>trip again and again?  What does the orbit evolve too?  Also, will the
>mission be limited by 1)expendables-attitude gas 2) power from the RTG
>etc. Is there political support at ESA for an extended mission?  Is JPL
>providing the communications and ESA the operations or what? Thanks..

I am not Ron Baalke :-), but maybe I can add a little.  From the STS - 41
Countdown Highlights, prepared by Marshall Space Flight Center, Rockwell
International Huntsville Operations:

Following its Jupiter encounter, Ulysses orbit will take it from a maximum
distance from the sun of approx. 500 million miles to its closest approach of
approximately 120 million miles.  The spacecraft will reach 70 degrees south
solar latitude in June, 1994 at a distance of approximately 200 million miles.
 The spacecraft's orbital position will remain to the south of 70 degrees
south solar latitude for about four months.  During this period the space
craft will be performing its primary mission studies of the sun's south polar
regions.  In February 1995, Ulysses will cross the ecliptic plane (the sun's
equator).  Beginning June, 1995, the spacecraft will perform the second phase
of its primary mission as it passes over the north polar regions of the sun.
The nominal mission will terminate in September, 1995 following the north
polar passage.

The spacecraft will, however, remain in a stable polar orbit around the sun.
The next polar passes will occur in 1999 - 2000.  Due to the gradual
degradation of the Radioisotope Thermoelectric Generation (RTSs), there will
be insufficient power at this time to assure full operation of the spacecraft.
However, a limited mission may be possible during this second set of polar
passes.  Mission operations will be conducted from the Jet Propulsion
Laboratory.  The operations will be conducted by a joint European Space Agency
(ESA) / JPL team.


--------->End of reading

Please, do not quibble with the terminology above, I am just typing what I
read.  Please send flames to /dev/null.

Ken Hollis

ProLine:  gandalf@pro-canaveral
Internet: [e-mail]
UUCP:     crash!pro-canaveral!gandalf

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

Date: Thu, 25 Oct 90 14:09 EST
From: [e-mail]
Subject: Re: Pioneer 11 article

Henry Spencer writes:
>result is fairly strong negative evidence that there is no major tenth
>planet.  (The effects on the Pioneer/Voyager trajectories would have been

Question:  How strong is "fairly strong?"  Does this mean that Pluto/Charon
are the most distant objects of significance in the solar system (excepting
the Oort Cloud), and what does this do to theories about the perturbations
of the orbit of the outer planets?  --> Furthermore, does this evidence
lend any support or remove it from the brown-dwarf solar companion idea?

Mark F. Jenkins
Bowling Green State University

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

Date: 25 Oct 90 00:02:01 GMT
From: [e-mail]  (Bill Seward)
Subject: results of query on skills

A week or so ago, I asked a question of this group.  The question was
"What set of skills would a computer professional need, besides
those already possessed, to work for NASA?"

I didn't get as many replies as I had hoped for, but I did receive some
good information fron a couple of NASA 'insiders'.

Each reply addressed a different area.  The first reply emphasized a
good basic knowledge of physics.  The problem quoted was trying to
explain programming needs to programmers who don't have the background
to understand the problemthat they are trying to address.

The second reply addressed a set of computer skill that the author
believed valuable.  Not quite on my intended topic, but interesting
anyway.  According to the author, the areas to be familier with
include C, Ada, FORTRAN and assembly languages; real-time programming;
Unix and distributed systems.

Thanks to both of you (and you know who you are) for the information.

------------------------------------------------------------------------------
| Bill Seward -- Analyst, Programmer, System Manager, User Training, and     |
|                whatever else needs doing.                                  |
|       Cutaneous Pharmacology & Toxicology Center, NC State University      |
| [e-mail]                            [e-mail] |
------------------------------------------------------------------------------

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

End of SPACE Digest V12 #493
*******************