Space & Astronomy/Space and Astronomy (October 1993).iso/mac/TEXT/SPACEDIG/V11_3/V11_333.TXT

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Subject: SPACE Digest V11 #333

SPACE Digest                                     Volume 11 : Issue 333

Today's Topics:
      Help! Best viewing time for Austin from Brisbane Australia
              Re: Fermi paradox
                 Sex in space
                 Hubble Orbit
Re: Not-so-Silent Running (Was Re: a bunch of other irrelvant things)
                Re: Our galaxy
                  Re: Radar
         Re: Materials (Was: Re: Energy consumption)
                  Re: Radar
     Re: PegBlimp (was Re: Pegasus launch from Valkyrie  (or ...)
         Apology for being on the East coast
----------------------------------------------------------------------

Date: 30 Apr 90 01:02:56 GMT
From: zaphod.mps.ohio-state.edu!samsung!munnari.oz.au!metro!bunyip!moondance!batserver.cs.uq.oz.au![e-mail]  (Anthony Lee)
Subject: Help! Best viewing time for Austin from Brisbane Australia

Could someone please tell me the current location (30-4 to 4-5) of
Comet Austin ?  What's the best time for viewing from Brisbane
Australia ?  My position is 27degree 30 minute South and 152 degree
30 minute East.

Thanks in advance
Anthony
--
Anthony Lee (Humble PhD student) (Alias Time Lord Doctor)
ACSnet:    [e-mail]    TEL:+(61)-7-371-2651
Internet: [e-mail]        +(61)-7-377-4139 (w)
SNAIL: Dept Comp. Science, University of Qld, St Lucia, Qld 4072, Australia

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

Date: 29 Apr 90 18:21:06 GMT
From: oliveb!tymix!hobbes![e-mail]  (Phil Nelson)
Subject: Re: Fermi paradox

In article <[e-mail]> [e-mail] (Christopher Neufeld) writes:
>In article <[e-mail]> [e-mail] (Phil Nelson) writes:
>>
>>With only one observable example of a planet with life on it, probability
>>is not a useful tool for answering this question. We need more information.
>>
>   No, I think you can say that the probability that there is exactly
>one life-bearing planet in the universe is no more than 1/e.

    (long analysis deleted)


  I assert that probability is not useful in such an extreme case, you
answer by doing an analysis. It looks very impressive to me, but it doesn't
change my point. I don't mean to discourage speculation, or to assert that
life does not exist elswhere, just that the assumption that life must exist
elsewhere because there are so many stars out there unscientific.


> Christopher Neufeld....Just a graduate student  | "Like most
> [e-mail]              | intellectuals he is


--

Phil Nelson . uunet!pyramid!oliveb!tymix!hobbes!pnelson . Voice:408-922-7508

    Treasures gained by wickedness do not profit,
             but righteousness delivers from death.     -Proverbs 10:2

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

Date: 29 Apr 90 21:10:34 GMT
From: snorkelwacker!bu.edu!dartvax!eleazar.dartmouth.edu![e-mail]  (Chris May)
Subject: Sex in space

Forgive me if this has already been discussed many times before,
but a friend and I are interested in knowing whether anyone has
had sexual intercourse while in orbit.  With the double-deck
shuttle and crew members of both sexes on many flights, it seems
someone might be able to do so (given the cooperation of one's
colleagues, of course).  Are there any technological barriers
(ahem...like short-circuiting the ship's electronics. . .you know
what I mean. . .0g sex seems like it could be rather messy)?
Has this been done as part of a regular physiological experiment,
or (more likely) as an unauthorized romp?  Who did it, if it has
indeed been done?  Would the offending couple be booted from the
astronaut program if caught?

Thanks,

--ccm

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

Date: 29 Apr 90 19:42:30 GMT
From: usc!cs.utexas.edu!news-server.csri.toronto.edu!qucdn![e-mail]
Subject: Hubble Orbit

Can someone out there tell me why they chose 380 miles as the height of
the Hubble orbit?  Was it just because the shuttle couldn't carry it any
higher?

 Mike Smith                                  [e-mail]
 Queen's University                          [e-mail]
 Computing and Communications Services       [phone]

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

Date: 29 Apr 90 15:50:28 GMT
From: mcsun!ukc!icdoc!syma![e-mail]  (Nick Watkins)
Subject: Re: Not-so-Silent Running (Was Re: a bunch of other irrelvant things)

In article <[e-mail]> [e-mail] (David Ray) writes:

>The movie sucked. It didn't make sense that a NASA-like space federation
>would have gone to all the expense and planning to build these space
>greenhouses, maintain them, have them work perfectly, and then decide
>to nuke then for beaurocratic reasons.

Have you heard of a Rocket called Saturn V ? There are 2 still available
for your contemplation if you haven't ...

Nick


--
Dr. Nick Watkins, Space & Plasma Physics Group, School of Mathematical
& Physical Sciences, Univ. of Sussex, Brighton, E.Sussex, BN1 9QH, ENGLAND
JANET: [e-mail]   BITNET: [e-mail]

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

Date: Fri, 27 Apr 90 15:43:24 +0200
From: mpirbn![e-mail] (Daniel Fischer)
Subject: Re: Our galaxy
Cc: [e-mail]

 In <23 Apr 1990 08:17 CDT> Will Martin <[e-mail]> asks:
> I have heard ... that our galaxy is ... a barred spiral. Were there indeed
> such news reports, and were they accurate?
The discovery in question was announced at the 175th meeting of the American
Astronomical Society; usually papers given there are *very* hot, and the
final versions do not appear in the scientific journals until many months
(or > 1 year) later. Regarding the type of our galaxy, the story was told e.g.
in the SCIENTIFIC AMERICAN Vol.262 (April 1990) p.12 and in the JOURNAL OF THE
BRITISH ASTRONOMICAL ASSOCIATION Vol.100 (April 1990) p.51. There we read:
] Leo Blitz (Maryland) and David Spergel (Princeton) ... have reexamined data
] on the velocities of hydrogen clouds relative to the rest of our galaxy...
] They have formulated a dynamical model... The new finding is that in the
] vicinity of the galactic centre the distribution [of matter, mostly stars]
] is more like a rugby ball (the Americans described it as a water melon) than
] a spheroid. Observed from the Andromeda galaxy, the Milky wWay would look
] like the mildest form of a barred spiral galaxy, perhaps similar to M58...

+- [e-mail] --- Daniel Fischer --- [e-mail] -+
| Max-Planck-Institut f. Radioastronomie, Auf dem Huegel 69, D-5300 Bonn 1,FRG |
+----- Enjoy the Universe - it's the only one you're likely to experience -----+

P.S.: Why don't you like "the Milky Way"? To me it preserves something of the
old romantic views of the sky. Furthermore, as far as I know, >>The Milky Way
Galaxy<< is the official name of our site here, at least in English. In German
it can be more confusing as some speak of 'the billions of milky ways'...

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

Date:         Sun, 29 Apr 90 13:08:03 CDT
From: John Nordlie <[e-mail]>
Subject:      Re: Radar

A lot of discussion is going on about the power dissapation of
radar signals over distance.  One fact that I have not seen
mentioned is that the inverse square law is being applied
to radar signals as if they were point sources, radiating energy
equally in all directions.  This is not the case with radar (or
just about any other radio transmission).  Radar is radiated from
an antenna in a highly directional beam.  Simply plugging in the
transmitter power and distance into the inverse square equation will
not give you an accurate estimation of signal strength.
The width and shape of the beam must also be taken into consideration.
I am not an EE, so I don't know what equations you need to solve
this problem.  Any radio-types out there know?
----------------------------------------------------------------------
  "I compute, therefore I am."           John Nordlie
----------------------------------------------------------------------

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

Date: Mon, 30 Apr 90 00:42:31 EDT
From: [e-mail] (Keith F. Lynch)
To: [e-mail]
Cc: [e-mail], [e-mail]

> I am under the impression that the ancients used much the same
> conventional names for the maria that we do today.

I looked it up - the maria and the mountain ranges were named by
Johannes Hevelius in the 1640s.  The major craters were named by
Giovanni Riccioli in the 1650s.

It's important to realize that before the 1600s, people had a very
different view of other worlds.  They weren't regarded as other
worlds at all, but as unchanging perfect luminous abstractions
endowed with perpetual motion, like Plato's ideals made visible.

Terrestrial matter was in random shapes, changed and decayed with
time, had sounds and smells, moved only when pushed, and was visible
only by reflected light.  Celestial matter was in perfect geometric
shapes, changed cyclicly if at all, never decayed, had no sound or
smell, moved without being pushed, and was luminous of itself.  The
sky was often identified with the abode of a perfect and all-powerful
God or Gods.

Galileo helped to overturn this view, by discovering mountains on
the moon, phases on Venus (which proved it circled the Sun, not the
Earth), spots on the Sun, moons of Jupiter, and stars not visible
to the unaided eye.  Newton finished the job by demonstrating how
the same physical laws can account for the behavior of all matter,
terrestrial or celestial, apples or moons.

The old view still survives in popular movies, in which aliens and
objects from space glow and glide effortlessly through the air.

> They are, after all, prominent to the naked eye.

They aren't clear enough that they can really be mapped and named.
The ancients accounted for them as reflections of the imperfect Earth
in the nearby moon.  (Meteors and aurorae were long recognized as
being in Earth's atmosphere.  Only comets were hard to explain away.)

> Kevin, KE9TV

Keith, formerly N4TP
                                ...Keith

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

Date: 29 Apr 90 03:11:37 GMT
From: usc!elroy.jpl.nasa.gov!zardoz.cpd.com!dhw68k!ofa123![e-mail]  (Wales Larrison)
Subject: Re: Materials (Was: Re: Energy consumption)

>>[Henry Spencer]
>>... Hermes will be mostly aluminum, for example, not
>>titanium like the shuttle.
>
>[George Herbert]
>The shuttle is good ole Aluminum alloys, much of it garden variety
>2024 and 7075 ... Which is not to detract from the general tone of
>your posting, which was that the shuttle pushed technology all over.
>It did, in almost all ways, and in retrospect building it out of
>titanium would have been a great idea because it would have ended up
>lot lighter with a corresponding higher payload, all for fraction of
>the total development cost...an example of bad early design economic
>failure.
>
    George is right, the shuttle primary structure is almost
exclusively made out of aluminum alloys.  (The alloy numbers look
right too...).  The only place on the primary structure that is not
alumimum is in the aft thrust structure, where the propulsive loads
from the 3 main engines and the ET/SRB stack are taken into the
orbiter.  This is a diffusion bonded titanium/boron composite
structure.  (And a real pain to build, I understand)
    But I disagree the selection of an all-titanium structure would
have reduced the shuttle development costs.   The choice of aluminum
over titanium for the primary structure was deliberate, as both
materials were considered in the Phase B and Phase C/D design studies
(see my previous posts for references).  The decision to go to
aluminum structure was primarily driven by the need to reduce
technical and programmatic risk.  While Titanium was stronger and
lighter it had several serious drawbacks - it was  more expensive,
was much more difficult to manufacture and shape, and had much worse
thermal properties.  Titanium was rejected on the bases of:  Don't
pick a material whose alloy properties were not very well known, for
which manufacturing processes were not well known, where material
availability could be an issue (the waiting list to get material for
large titanium parts was over 40 months at that time!), and which
would cost more.  Analyses indicated that picking titanium as the
primary structure would reduce the vehicle weight, would increase
the development cost, the materials cost, and the production cost.
This, plus programmatic (cost, schedule, and manufacturing) risk,
outweighed marginal savings from the increased performance.
   Lesser known, but just as important (at least according to the
references), was that titanium's thermal coefficent was  less than
aluminum.  In the event that a tile would be lost, or that reentry
flow would allow localized "hot spots" to develop on the shuttle,
titanium would not allow the heat to soak easily into  structure.
An aluminum structure, on the other hand, would allow the heat to
more easily spread over the whole primary structure, reducing the
appearance and hazard from localized hot-spots. While this property
was not enough to eliminate the hazard from major losses of tile,
analyzes showed the potential for damage from localized failures in
the technically-risky thermal protection system was reduced by
choosing aluminum.  By picking aluminum, the designers sacrificed
some performance, but they did so to reduce development cost,
development risk, manufacturing cost, and technical risks in other
areas where the risk was much higher.
-------------------------------------------------------------------
Wales Larrison             Space Technology Investor
"I don't care if it works, I can make it better"(Anonymous engineer)
"Shoot the engineers, give me something that works....."


--- Opus-CBCS 1.12
 * Origin: Universal Electronics, Inc. (1:103/302.0)
--
Wales Larrison
...!{dhw68k,zardoz,lawnet,conexch}!ofa123!Wales.Larrison                             [e-mail]
714 544-0934 2400/1200/300

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

Date: 29 Apr 90 21:59:11 GMT
From: usc!cs.utexas.edu!news-server.csri.toronto.edu!utgpu!utzoo![e-mail]  (Henry Spencer)
Subject: Re: Radar

In article <[e-mail]> [e-mail] (John Nordlie) writes:
>... Radar is radiated from
>an antenna in a highly directional beam.  Simply plugging in the
>transmitter power and distance into the inverse square equation will
>not give you an accurate estimation of signal strength.

A directional antenna turns out, as I recall, to be the equivalent of a
rather more powerful source some distance behind the antenna, with the
antenna looking like a "window" on the source's emissions.  This alters
the inverse-square situation only slightly at the sort of distances
involved, provided you remember to allow for the greater effective power.
--
If OSI is the answer, what is |     Henry Spencer at U of Toronto Zoology
the question?? -Rolf Nordhagen| uunet!attcan!utzoo!henry [e-mail]

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

Date: 29 Apr 90 06:59:32 GMT
From: usc!jarthur!nntp-server.caltech.edu!gap![e-mail]  (David Palmer)
Subject: Re: PegBlimp (was Re: Pegasus launch from Valkyrie  (or ...)

[e-mail] (Russ Cage) writes:
>Time for me to question YOUR numbers:  The B-52 and many other
>aircraft can fly at 50,000 ft plus.  You mentioned a figure of
>3 times that (150,000 ft) as an altitude reachable by balloons.
>How many research balloons have been that high, and how much
>did they carry?  Anything even *close* to Pegasus size?
>According to my CRC, the air density there is about 1 g/m^3;
>supporting a 20,000 kg load would require a balloon with a
>volume of at least 20 million meters^3, or 700 million ft^3!
>That's a sphere 1100 feet in diameter!  Are you for real?

Big scientific balloons are up to 70 million ft^3.

A 23 million ft^3 balloon will carry about 4500 lbs to 120,000 feet
(sorry for the archaic units, but it's what the National Scientific Balloon
Facility uses).  This is exclusive of the balloon itself.  If you are
willing to settle for 100,000 feet, you can probably double the payload.

But one huge advantage of Pegasus is it's ability to launch
at short notice.  Balloons are very difficult to launch.  It
is quite common to make half a dozen launch attempts,
waiting for the wind to drop down to less than 8 knots or
so (for a 23 million ft^3), steady and predictable.
The wind direction must be predicted to within about 30 degrees a couple
of hours before launch.

Launching from an airplane is much much easier.

--
        David Palmer
        [e-mail]
        ...rutgers!cit-vax!gap.cco.caltech.edu!palmer
    I have the power to cloud men's minds -- or at least my own.

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

Date: 28 Apr 90 00:06:35 GMT
From: eagle!amelia!wilbur.nas.nasa.gov![e-mail]  (Eugene N. Miya)
Subject: Apology for being on the East coast

Over the past few weeks, I had a business trip to the East coast
and it turns out that the hosts where I normally read news (eos.arc....
and aurora.arc...) have been down for a move to a new building
[not my building].  I am just now getting to backlogged
mail/requests/employment etc. etc.  If your mail bounced, and you didn't
see the alternative mailbox below, please retry now.  You might remember
I used to have a different signature which talked about mailers.
But that's history.

Note: sending paper mail to a Center's public information office can
yield tons more information of a less sensitive nature than I have.
[Addresses from the month FAQ posting.]
I know, I got tons of paper mail as a kid writing to NASA while
growing up.  Right now, I'm more concern with performance measurement of
high performance computer architectures.

For interested future astronaut candidates, I've almost copied the
entire intro on applying.  This will shortly become a monthly
frequent questions posting in sci.space.  And, no, I don't have time to
read sci.space, but I've got other eyes reading for me, and I can tell
you still have flaming, cyclic discussions. ;)

And remember for employment mail: NASA is an Agency of the United States
Government.  US citizenship is required.  Other than that it's
yet another attempt at being an "Equal Opportunity Employer...."

--e. nobuo miya, NASA Ames Research Center, [e-mail]
  {uunet,mailrus,other gateways}!ames!eugene

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

End of SPACE Digest V11 #333
*******************