Space & Astronomy/Space and Astronomy (October 1993).iso/pc/text/spacedig/v15_1/v15no155.txt

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Date: Wed,  2 Sep 92 05:01:21
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Subject: Space Digest V15 #155
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Space Digest                Wed,  2 Sep 92       Volume 15 : Issue 155

Today's Topics:
                        Inflationary universe
                   LDO shuttle and pilot readiness
                             Oil workers
                            Rats in space
                                 SPS

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Date: Tue, 1 Sep 1992 13:46:18 GMT
From: Hartmut Frommert <[e-mail]>
Subject: Inflationary universe
Newsgroups: sci.astro,sci.space,sci.physics

[e-mail] (Ahmed Abd-Allah) writes:

[..]

>To make a long story short: where is the following thought experiment
>wrong?

>If the universe started out as a finite ball that got bigger and
>bigger, then that means that today it is just a bigger ball, right?

Right.

>If Omega is one, then this means that the expansion is slowly approaching
>zero, I believe - but never quite reaching it.

Right.

>Does this mean that, if
>we were 'immortal', we could head out in some space travel vehicle
>which chugs along at some constant speed which would EVENTUALLY be greater
>than the speed of expansion - so in a flat universe we WOULD end up
>back where we started?

If the universe has a trivial topology, and the cosmological constant Lambda
is ZERO (that is the "standard standard" cosmological model) then of course
not. Otherwise it MAY be possible to reach the same place IN 3-SPACE, i.e.
crossing the world-line of a particle-at-rest ("the Earth") after
circumnavigating the universe. IF that's posible depends on topology,
Lambda and the matter contents of the universe, as well as possible
modifications of GR.

>Just that if we tried to repeat the same journey, it
>would be different?

Again dependent on the items given above.

>I guess I am having trouble understanding why having a forever expanding
>finite universe means that it is infinitely large TODAY.  It can't be
>right?  At any point in time, a flat universe will be finite in size.

There are flat as well as positively and negatively curved universes
(solutions of the cosmological eq's) which are finite, and others that
are infinite in volume. I think it's not clear how this topological property
can change, so the universe should be either finite or infinite at any time.
--
 Hartmut Frommert, Physics, Univ of Constance, | + Whale killing is murder. +
 P.O.Box 55 60, D-W-7750 Konstanz, Germany | + Eat whale killers, not whales.
 E-Mail: <[e-mail]> or <[e-mail]>
+    "Windows NoT" expands in German to "Windows Noch Teurer"
+                                                ^even   ^more expensive

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

Date: Tue, 1 Sep 1992 17:01:57 GMT
From: Mark Littlefield <[e-mail]>
Subject: LDO shuttle and pilot readiness
Newsgroups: sci.space

In article <[e-mail]>, [e-mail] (GRASSO CHRISTOPHER A) writes:
|> After being on orbit for 2 months, how realistic is it for a shuttle pilot
|>     to be capable of performing a reentry and landing? Seating in the
|>         shuttle is upright, airliner-style, while seating in a capsule is
|>         reclined to horizontal.
|>
|>     If the extended stay in microgravity damages the shuttle pilots'
|>     ability to bring the spacecraft back for a landing, doesn't this
|>     mandate a separate ACRV if shuttle is to be used for resupply and
|>     crew rotation?
|>
|>         -Chris
|>
|>
|> --
|>  Chris Grasso
|>  CSC
|>  Univ. of Colorado, Boulder
Besides the obvious problems associated with microgravity, the pilot
has had 2 months in which he (or she, as there's a woman pilot now)
has done no training.  Now, if you ask a fighter pilot how their reactions
are after a 2 month break from training, they'll tell you that after
as short a time as 2 week skills begin to degrade.  I'd hate to see
what a shuttle pilot is like after 2 months of no sim time.

=====================================================================
Mark L. Littlefield              Intelligent Systems Department
internet: [e-mail]
USsnail:  Lockheed Engineering and Sciences
          2400 Nasa Rd 1 / MC C-19
          Houston, TX 77058-3711
====================================================================


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

Date: 1 Sep 92 12:22:35 GMT
From: John Roberts <[e-mail]>
Subject: Oil workers
Newsgroups: sci.space

-From: [e-mail] (Nick Szabo)
-Subject: Re: SPS feasibility
-Date: 20 Aug 92 09:40:44 GMT

-In article <[e-mail]> [e-mail] (Tom) writes:
->Imagine how cheap shuttle launches would
->be if the workers were paid comparably to Arabian oil workers.

-Imagine how expensive Saudi oil would be if the oilfield workers cost
-the same as astronauts, $10 million per hour.  :-(

Interesting that this was chosen as an example. I don't know about native
workers, but US engineers are sometimes hired to work in Saudi Arabia for
a few months to a year or more, at sky-high wages. I knew one fellow who did
that. He liked it pretty well, but his wife eventually got tired of having to
wear heavy clothes, not being allowed to drive, etc.

John Roberts
[e-mail]

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

Date: 1 Sep 92 12:11:20 GMT
From: John Roberts <[e-mail]>
Subject: Rats in space
Newsgroups: sci.space

-From: [e-mail] (Frank Crary)
-Subject: Re: With telepresence, who needs people in Earth orbit?
-Date: 21 Aug 92 15:19:12 GMT
-Organization: U. C. Berkeley Open Computing Facility

-You might want to bounce this idea off a lab biologist: Experimental
-animals require _alot_ more than picking them up, putting them in
-the experiment and then putting them back in a cage. For example, they
-will sometimes actively resist being taken out of their cage (or put
-back in it), get away from who (or what)ever is carrying them back and forth,
-escape from their cages (requiring a very different sort of work to
-find again, etc...

That reminds me of my favorite space life sciences disaster scenario:

1) Shuttle astronauts on a biology mission, perhaps in the process of
making educational videos, decide that it would be great to show a rat
in midair, so one is released from its cage.

2) Rat amusingly runs in place in midair for a while.

3) Rat eventually is nudged or drifts until it contacts a wall, at which
point it takes off like a shot.

4) Before astronauts can react, rat has bounded onto flight deck, where it
naturally leaps through small access hole under dashboard and out of reach
of the astronauts, then it immediately begins to chew on all wires within
reach.

(The rat's name is Murphy, by the way. :-)

One would *hope* there are pretty stringent measures to prevent the rats
from getting loose.

Note that one method of rat/mouse transfer (picking it up by the tail to
prevent biting) wouldn't work in microgravity. I suppose you could improvise
by swinging the animal around in a circle, but it would look pretty silly.
Maybe a pair of crab tongs would work.

John Roberts
[e-mail]

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

Date: 1 Sep 92 12:33:38 GMT
From: John Roberts <[e-mail]>
Subject: SPS
Newsgroups: sci.space

-From: [e-mail] (Dani Eder)
-Subject: Re: SPS feasibility (WAS: SPS fouling astronomy)
-Date: 17 Aug 92 15:48:05 GMT
-Organization: Boeing AI Center, Huntsville, AL

-In reference to Earth heat balance calculations, I disagree with
-Mr. Coffman.  If terrestrial solar power is used, whether PV or
-thermal, you have to locally increase absorbtion of sunlight, since
-both PV cells and solar collectors are effectively darker than the
-ground over which they are built.  A darker earth is a warmer earth,
-despite the shifting of the heat load from the collector to the end
-using machines by way of electrical transmission lines.

It's not *quite* that simple, since darker surfaces also radiate more
efficiently at night. Darkness at various parts of the spectrum (including
thermal infrared) and the concentration of greenhouse gases (produced by
burning fossil fuel - another factor) have to be taken into account.

-In the case of microwave (not laser) SPS, the receiving antenna
-(rectenna) is metal, which tends to reflect more sunlight than
-the gound over which it is built.  If needed, the rectenna can
-be painted white to reflect even more.

And then it would radiate heat less effectively at night.

-Diamonds currently go for about $1000 per carat, or $5 M per kg.

I can see a 1-carat gem-quality, faceted diamond going for that price. A
raw diamond of that size or one of lesser quality should be much less. A large
gem-quality diamond is probably worth much more than that per carat.

John Roberts
[e-mail]

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        The Soviets were the first nation to place unmanned rovers on
    the surface of the planet Mars back in 1971, though unfortunately
    they were never able to utilize them.

        The MARS 2 and 3 mission plan was to orbit the Red Planet and
    place unmanned landers (similar in design to the LUNA 9/13 landers
    of 1966) on the planet and transmit data to Earth.  The landers
    also carried several small rovers attached to the craft by fifteen
    meter tethers.  They were to maneuver around the landing site and
    analyze the soil.  The landers were never used due to the apparent
    crash landing of MARS 2 and the communications failure of MARS 3
    after ninety seconds of transmission from the surface.

        This information was first revealed to the West in July/August
    1990 issue of The Planetary Society magazine THE PLANETARY REPORT.
    The issue includes a black-and-white photograph of the rover.

        Since the landers of the MARS 6-7 mission of 1974 were similar
    in design to MARS 2-3, it is possible that they too carried small
    rovers.  However, the MARS 6 lander crashed upon landing and MARS 7
    missed the entire planet and drifted off into solar orbit.

        The PHOBOS 1-2 mission landers were not rovers, though one
    lander was designed to hop across the moon's surface using metal
    bars.  The other lander type was to be anchored into the ground
    with a harpoon.  The mission never happened as planned when PHOBOS
    1 failed enroute in 1988 and its sister craft ceased transmitting
    while in Mars orbit just one week before the landing in 1989.

        Larry Klaes  [e-mail]
             or - ...!decwrl!verga.enet.dec.com!klaes
                 or - [e-mail]
                     or - [e-mail]

             "All the Universe, or nothing!" - H. G. Wells

        EJASA Editor, Astronomical Society of the Atlantic

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End of Space Digest Volume 15 : Issue 155
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