Space & Astronomy/Space and Astronomy (October 1993).iso/mac/TEXT/SPACEDIG/V08/V8_345.TXT

Internet Message Format | 1991-07-08 | 19KB

Return-path: <[e-mail]>
X-Andrew-Authenticated-as: 0;andrew.cmu.edu;Network-Mail
Received: from po2.andrew.cmu.edu via trymail for +dist+/afs/andrew.cmu.edu/usr1/ota/space/[e-mail] (->+dist+/afs/andrew.cmu.edu/usr1/ota/space/space.dl) (->ota+space.digests)
          ID </afs/andrew.cmu.edu/usr1/ota/Mailbox/po2.andrew.cmu.edu.338.0.0>;
          Thu,  1 Sep 88 04:14:18 -0400 (EDT)
Received: from andrew.cmu.edu via qmail
          ID </afs/andrew.cmu.edu/service/mailqs/q007/QF.andrew.cmu.edu.231d04d9.56a174>;
          Thu,  1 Sep 88 04:06:30 -0400 (EDT)
Received: by andrew.cmu.edu (5.54/3.15) id <AA00351> for +dist+/afs/andrew.cmu.edu/usr1/ota/space/space.dl; Thu, 1 Sep 88 04:04:27 EDT
Received: by angband.s1.gov id AA06589; Thu, 1 Sep 88 01:05:43 PDT
    id AA06589; Thu, 1 Sep 88 01:05:43 PDT
Date: Thu, 1 Sep 88 01:05:43 PDT
From: Ted Anderson <[e-mail]>
Message-Id: <[e-mail]>
To: [e-mail]
Reply-To: [e-mail]
Subject: SPACE Digest V8 #345

SPACE Digest                                      Volume 8 : Issue 345

Today's Topics:
          Re: space news from July 11 AW&ST
   Self-reproducing probes (was: SETI: Why don't we hear anything?)
             Satellite brightness
         Re: ET phone home? (SETI)   RESPONS
                   Re: Seti
            Re: 95% vs. 99.9% reliability
                   Re: Seti
           Re: space news from Aug 1 AW&ST
                  nutrition
               Re: Ozone layers
----------------------------------------------------------------------

Date: 18 Aug 88 15:57:21 GMT
From: uplherc!esunix![e-mail]  (Bob Pendleton)
Subject: Re: space news from July 11 AW&ST

From article <[e-mail]>, by [e-mail] (Henry Spencer):
> ... Earliest full operational date
> for ALS is about the year 2000.  There is also a great deal of skepticism
> about whether ALS can really achieve its goal of a factor of 10 reduction
> in launch costs, and some doubt about whether it is really wise to pack
> many small payloads together into one launch.

A recent issue of Aerospace America had an article on ALS. It seems
that one of the main problems they are having is convincing engineers
that COST not performance is the major design factor. (A problem I'm
all too aware of.) Sexy technical solutions are not always the most
cost effective solutions.

A lot of people don't think that ALS can meet its cost goals. Just as
a reality check I put together this table. The numbers are all from
memory so acurracy is doubtful. It is based on the space shuttle.
Assuming a max payload weight of 43K lbs., an orbitor weight 150k
lbs., and an external tank weight of 75K lbs. I wanted to compute
costs of a pound in orbit counting just the payload weight, the
orbitor plus the payload, 193K lbs., and the orbitor plus the payload
plus the ET, 268L lbs., as delivered weight in orbit. I used three
different costs for a shuttle launch. They are all close to figures
I've heard, but I'm not sure anyone really knows what a shuttle launch
costs. So I've used $100M, $200M, and $300M.

    $100M    $200M    $300M
P     2325     4651     6976
P+O      518     1036     1554
P+O+ET      373      746     1119

Nothing about the shuttle was designed to be cheap. It was designed to
be reusable, and designed to have the very highest perfomance. It
looks like an expendable vehicle based on shuttle technology should
be able to put a payload of something less than P+O, say 150K lbs.
into orbit for a cost less than $2000/lb assuming $300M per launch.
(shades of Shuttle-C!)

It seems to me that a reduction in launch preparation cost, without a
reduction in vehicle cost, might be able to get you under $1000
dollars per pound. If you through in enough mights and maybes you can
convince yourself that $300 a lb. is achievable.

For a further reality check look at the Soviet proton and energia
boosters.

I'm starting to believe that the main reason ALS will
have trouble reaching its design goals is the "performance is
everything", "high tech or nothing" mind set of the companies doing
the work.

            Bob P.
--
Bob Pendleton @ Evans & Sutherland
UUCP Address:  {decvax,ucbvax,allegra}!decwrl!esunix!bpendlet
Alternate:     utah-cs!esunix!bpendlet
        I am solely responsible for what I say.

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

Date: 19 Aug 88 18:04:57 GMT
From: tektronix!orca!tekecs!blast![e-mail]  (Kendall Auel)
Subject: Self-reproducing probes (was: SETI: Why don't we hear anything?)

In article <[e-mail]> Steve Willner writes:
>If it is possible for an advanced civilization to build and deploy
>self-reproducing, interstellar probes, probes could be continuously
>resident in each solar system.  If the civilization constructing the
>probes were irrationally hostile to other life forms, the probes
>could be programmed to detect life and sterilize any planets long
>before radio could be developed.

I'm curious what a self-reproducing interstellar probe would be
like.  We tend to think of Voyager and the like, but genetic
engineering may change our definition of "machine".  Maybe WE
are the self-reproducing probe :-).  There is a sci-fi story called
"The Seed", where a scientist discovers the true origin of life.
It was planted on Earth by a highly advanced civilization that
prizes smooth, shiny planets.  The alien race knew that eventually
the seed would grow to build H-bombs that melt the planet's crust.
I can't remember who wrote it, but I found it very entertaining.

Kendall Auel               ^ ^
                  /O O\
Tektronix, Inc.              | V |
Information Display Group    /  """  \
Graphics Workstations Division    / """"" \
([e-mail])     /|\ /|\

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

Date: 19 Aug 88 18:32:04 GMT
From: nbires!isis!scicom![e-mail]  (Bruce Watson)
Subject: Satellite brightness


Here is a short list of the brightest artificial earth satellites:

 Mag  Satellite
 ---  ---------
-2.5  Space Shuttle
-2.0*` KH-11
-2.0  Cosmos 1870
-0.5* MIR/Kvant/Soyuz TM/Progress complex
 0.0  Cosmos 1900 (to decay soon)
+1.0* Salyut 7/Cosmos 1686
+1.0  Cosmos 1834
+1.0  Cosmos 1890
+1.0  Cosmos 398 (highly elliptical orbit)
+1.0  LDEF
+1.5  Cosmos 56
+1.5  Cosmos 206

*=Confirmed by my observation.  Others are estimates.

Comments?  Additions or Corrections?

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

Date: 19 Aug 88 21:00:36 GMT
From: attcan!utzoo![e-mail]  (Henry Spencer)
Subject: Re: ET phone home? (SETI)   RESPONS

In article <96500002@datacube> [e-mail] writes:
>... given our fairly unimpressive track record, their
>elusive behavior could be due to a desire not to contact us...

The problem with this is that it assumes that the galaxy is culturally
homogeneous, so this argument applies to all intelligent species.  It
is not hard to construct any number of plausible arguments about why
one species would not contact us.  It is much harder to make those lines
of argument apply to *all* species in a galaxy that ought -- by what we
know -- to be teeming with them.  One would expect a certain amount of
variation in the behavior of intelligent species.

There are also moderately good biological arguments indicating that if
Earth is in quarantine, it has been in that state for several billion
years.  Not only must the galaxy be culturally homogeneous, it must have
been so for rather a long time.

This *could* be the explanation of the Great Silence, but it requires
rather a lot of assumptions.
--
Intel CPUs are not defective,  |     Henry Spencer at U of Toronto Zoology
they just act that way.        | uunet!attcan!utzoo!henry [e-mail]

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

Date: 19 Aug 88 21:28:07 GMT
From: attcan!utzoo![e-mail]  (Henry Spencer)
Subject: Re: Seti

In article <[e-mail]> [e-mail] (Paul F. Dietz) writes:
>A spacefaring society, even one restricted to a single stellar system,
>could have many trillions of members (but technology may make the concept
>of an individual obsolete), and each member could have a productivity orders
>of magnitude greater than 20th century Americans.  I would be very careful
>when proclaiming limits on what technological advances such a society might
>accomplish given millions of years.

I second this comment.  Consider:  There are people alive today who remember
a time when radio did not exist, man could not fly, and the total electrical
generating capacity of the world was measured in megawatts.  Today...  We
get live TV from Halley's Comet.  There is never a time, day or night, when
FEWER than a hundred thousand people are airborne.  And one gigawatt is a
single power plant, and not a really big one at that.

Our own world, and our own society, has changed beyond recognition in a
single human lifetime.  Never mind the millions of years; extrapolating our
capabilities a measly *thousand* years is quite impossible.
--
Intel CPUs are not defective,  |     Henry Spencer at U of Toronto Zoology
they just act that way.        | uunet!attcan!utzoo!henry [e-mail]

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

Date: 19 Aug 88 18:24:01 GMT
From: attcan!utzoo![e-mail]  (Henry Spencer)
Subject: Re: 95% vs. 99.9% reliability

In article <[e-mail]> [e-mail] (Gregory N. Hullender) writes:
>I imagine they would also have sent various officials from Morton Thiokol
>and Nasa off to the Gualag, if not had them shot.

Sounds like a fine idea to me.  A good many of them deserved it.

>As I recall, a fair amount of the pressure for putting safety first came
>from the astronauts themselves...

True... but it's also true that there would have been no shortage of
volunteers to fly high-priority missions before definitive fixes were made.
Bear in mind that you've seen a biased sample:  the safety-first astronauts
like Sally Ride were the ones who got the publicity.

>Fortunately, we don't live in the Soviet Union; however, considering your
>callous disregard for human life and warm regard for the power of a police
>state to stifle dissent, perhaps you should consider relocating.

Tsk, tsk, let us avoid name-calling.  I don't consider it "callous disregard
for human life" to suggest that it is sometimes appropriate to let volunteers
take risks in a good cause.  (Especially since, given the chance, I'd be at
the head of the line.)  Nor do I think it to be "warm regard for the power of
a police state to stifle dissent" to suggest that current US politics give
too much weight to dissent -- any dissent -- and to endless debates about
contentious issues, and not enough to making decisions in a timely way and
getting the job done.  2.5 years after the Apollo fire, Armstrong and Aldrin
walked on the Moon.  Today, 2.5 years after Challenger, we're still waiting.
--
Intel CPUs are not defective,  |     Henry Spencer at U of Toronto Zoology
they just act that way.        | uunet!attcan!utzoo!henry [e-mail]

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

Date: 19 Aug 88 21:20:31 GMT
From: attcan!utzoo![e-mail]  (Henry Spencer)
Subject: Re: Seti

In article <[e-mail]> [e-mail] (Gerry Roston) writes:
>1) Intelligent life forms elsewhere have life spans that are similar in magnitude
>   to ours (say 50-500 years)

A poor assumption; our own lifespan is likely to increase dramatically within
the next century or so.

>2) Advanced civilizations are energy bound (I know, fusion might solve that, but...)

Have you looked at a graph of the energy available to mankind over the last
century?  It's difficult for people today to realize just *tiny* mankind's
resources were a mere half-century ago.  There is no obvious reason for the
trend to change, either; certainly there are no technological barriers
visible in the near future.  Capturing a small but significant fraction of
the total energy output of the Sun would be enormously expensive (by 1988
standards) but appears to present no fundamental difficulties.

>3) Advanced societies have limited budgets and would expect a return on investment

Again, check out the pattern in our immediate past.  Emigrating to North
America -- just the passage and the necessary startup supplies -- took
every cent the Plymouth Rock colonists had, and drove them so deep into
debt that it was 20 years before they were in the black again.  The Mormons
merely had to spend their entire life savings to emigrate to Salt Lake City.
I went to Australia for Christmas last year; it was expensive enough to
be annoying.  See the trend?  The maximum-probability projection is that
future human societies will be enormously wealthier than our own.

>4) Einstein's theory of general relativity is true

Actually, if you're thinking of the speed-of-light limit, you want special
relativity, not general relativity.

>... the simple answer is that -
>it is not:
>1) Financially feasible; if they are so advanced, what would the hope to get from us?

What's the financial return on climbing Mount Everest?  Or on operating
Fermilab?  The simple answer to your question is "knowledge".

>2) Politically practicle; what would be the point of an interstellar (commerce,
>   trade agreement, cultural exchange, etc. ), if it takes tens to hundreds of
>   years for messages to get from on civilization to the other.

In earlier times on Earth, it wasn't uncommon for trade to take place along
routes where travel from one end to the other (a trip made by goods and money
but seldom by people) would take years.

>3) Easily understandable from an individual perspective; what individual would
>   leave behind FOREVER, everything he/she/it knows about on the very remote
>   possibility of discovering another intelligent species? ...

If one can assume robot precursors that would establish where intelligent
life is to be found, then the uncertainty largely vanishes.  As for who
would leave everything he/she/it knows behind forever, essentially everyone
who settled North America did just that.  And as Forward has pointed out,
the opportunity to spend the rest of your life studying a new solar system
is one that would attract an ample supply of volunteers among scientists.
--
Intel CPUs are not defective,  |     Henry Spencer at U of Toronto Zoology
they just act that way.        | uunet!attcan!utzoo!henry [e-mail]

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

Date: 20 Aug 88 07:17:11 GMT
From: [e-mail]  (Joe Beckenbach)
Subject: Re: space news from Aug 1 AW&ST


    VIMS is off the Mars Observer. The radar altimeter will be replaced
by a laser altimeter, leaving a bit more room on the nadir panel. High on
the Mars Observer Camera wish list is extra area for all the fun memory
chips needed for the on-board processing, the megabit chips [MOC requires
12 Mbytes] and the radiation-hard microprocessors, and all the other
electronics for instrument high performance. MOC wants to fly several
previously unflown [and, until now, untested] ICs; this should open
up the sophistication of instrumentation onboard future craft.

    Quick expansion on the instrument shuffle: the intent to include
a Russian receiver on the Mars Observer in support of an intended 1994
Russian mission with a French balloon experiment, forced the decision
to not delay launch until 1994. Besides, NASA HQ thought it wiser to
cut back on one instrument than to throw several instruments into a two-year
funding hold. [I believe the balloon is French: the faxed information
came in from Nice under the auspices of one of the French space research
groups.]

    Other brief notes: the engineering model of the Camera housing
went quite well, despite higher resonance amplitudes than expected.
The graphite-epoxy structure looks good in the photos I've seen; a show
last weekend [forget which one] had it on display. Fabrication of the
electronics and focal plane linear-array charge-coupled devices [CCDs]
are part of the next few months' efforts towards the production of the
engineering model. And even a cleanroom on campus by Thanksgiving for
putting the engineering model together [and flight model as well, if I
remember the schedules rightly].

    If the other teams are going along the way this team is, the
Mars Observer should be a solid piece of engineering ready in plenty of
time for the scheduled launch. Too bad I won't be in on this after
the start of September....
--
Joe Beckenbach    [e-mail]    Caltech 1-58, Pasadena CA 91125
Mars Observer Camera Project            Caltech Planetary Sciences Division
Ground Support Equipment Programmer [until 6 Sept, but can contact them much later]

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

Date: 20 Aug 88 13:04:40 GMT
From: portal!cup.portal.com![e-mail]
Subject: nutrition

maybe i'm just fishing for a job here but....

Is there a nutritionist at NASA that does stats on all the space jocks?
I mean here these people are on the cutting edge of science, and when
it comes to monitering what they eat, I hear nothing.

I mean Scientific American has had some VERY interesting articles on
what happens to the brain with intake of protein vs. carbos...

There are serveral articles on MEDLINE about nutrients and immune system
simulation...they don't want a cold while they are up there...it would
seem to me.

Have there EVERY been any studies made on nutrition vs. performance at
NASA? [I checked with their library and found very little]
I have hear about the bed rest deal for potential astronauts, any of
them take any extra vitamin c?

just wondering

lee wells

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

Date: 20 Aug 88 15:50:51 GMT
From: tektronix!tekcae!vice![e-mail]  (Keith Lofstrom)
Subject: Re: Ozone layers

Chlorine and Flourine are reputed to act as a catalyst in the O3 -> O2
reaction.  One of my sources suggests that, as a catalyst, it also
facilitates the other reaction.  The result:  at night, ozone decreases
"more than normal", and during the day, ozone INCREASES "more than normal".

Thus, the amount of daytime UV decreases (this is borne out by measured data)
and the amount of nighttime UV increases.  But since twice nothing is
still nothing, who cares?

Important question - the "ozone hole" in Antarctica increase was measured
DURING THE WINTER, when there is no sunlight near the pole.  Has the
same decrease been measured during the SUMMER?  Do the instruments even
work in sunlight?

Keith
--
Keith Lofstrom   ...!tektronix!vice!keithl   [e-mail]
MS 59-316, Tektronix, PO 500, Beaverton OR 97077  (503)-627-4052

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

End of SPACE Digest V8 #345
*******************