Space & Astronomy/Space and Astronomy (October 1993).iso/mac/TEXT/SPACEDIG/V11_3/V11_354.TXT

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Subject: SPACE Digest V11 #354

SPACE Digest                                     Volume 11 : Issue 354

Today's Topics:
        Re: (How to get rid of) space garbage
        Gravity (was Re: Radar (was Re: Drake Equation
            Re: Re: Dyson spheres?
Re: Not-so-Silent Running (Was Re: a bunch of other irrelvant things)
              Re: Decompression
   Two communications satelllites to be launched in May (Forwarded)
       Re: NASA Headline News for 05/02/90 (Forwarded)
        Re: (How to get rid of) space garbage
               Manned mission to Venus
            Re: Voyager Update - 05/02/90
----------------------------------------------------------------------

Date: 3 May 90 17:17:26 GMT
From: swrinde!zaphod.mps.ohio-state.edu!sdd.hp.com!elroy.jpl.nasa.gov!aristotle![e-mail]  (Peter Scott)
Subject: Re: (How to get rid of) space garbage

In article <[e-mail]>,
[e-mail] (Christopher Neufeld) writes:
> In article <[e-mail]>
[e-mail] writes:
> >Of course, one would hope that it wasn't in the wrong position when
> >Hubble came around one orbit, or whoops...
> >
>    Well, I chose 80000km for my proposal. It's out of the way of pretty
> well everything. This scheme wouldn't be workable in LEO because of the
> very low density of the sail needed to hold up against 1g of acceleration
> (remember, the object isn't orbiting, so there is no "centrifugal
> pseudo-force").

Well, actually I was thinking of accidentally shining the beam down the
barrel of the HST... there are a number of other satellites out there
one would not want to do this to, the aiming of this thing would have to
be carefully worked out.  After all, it doesn't sound as though it would
be practical to turn it off.

This is news.  This is your       |    Peter Scott, NASA/JPL/Caltech
brain on news.  Any questions?    |    ([e-mail])

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

Date: 3 May 90 14:09:53 GMT
From: [e-mail]  (David Salzberg)
Subject: Gravity (was Re: Radar (was Re: Drake Equation

In article <[e-mail]> [e-mail] (Philip Walden) writes:
-Actually you are all right. Close to the array or high gain antenna
-(probably about a few aperture lengths) the radiation will exhibit
-a more linear effect with distance. Much farther away, everything
-looks like a point source and exhibits the inverse-square relationship.
-This applies to all fields, such as gravity. A flat earth of infinite
-radius would have a constant gravitational field with height. This is
-true even on our spherical earth. Within a few thousand feet of the
-surface, most calculations can consider the strength of gravity as
-a constant.

In fact, geophysicists who study gravity anomolies assume a flat earth.
This is not a bad approxmiation because on the scales event of a
thousand km, the earth is essentially flat (that is, the curvature would
change baseline measurements by 1.3%, which is far lower than
observational errors).  This approximation of a flat earth does not work
on large, planet scale observations (such as free oscliations) or for
highly precisie measurements (such as VLBI), but for some work, the
earth is considered to be flat (for mathmatical simplifications).

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

Date: Thu, 3 May 90 18:10:37 EDT
From: John Roberts <[e-mail]>
Disclaimer: Opinions expressed are those of the sender
    and do not reflect NIST policy or agreement.
Subject: Re: Re: Dyson spheres?


>From: usc!cs.utexas.edu!news-server.csri.toronto.edu!utgpu!watserv1!maytag!watdragon!watyew![e-mail]  (Brian or James)
>Subject: Re: Re: Dyson spheres?

> I'd like to point out that my 'second rate' Dyson sphere at least
>requires no superstrong materials or phenominal orbit coordination
>to build and maintain. The heat problem is a pain, but I suspect it
>can be dealt with, with perhaps a minor cost in the Sun's life
>expectancy :).
>                            JDN

No offense intended - it's a clever idea. The only shortcoming (other than
possibly burning out the sun) is the low density of the spherical surface -
it would have to be mostly sail. If a person plus habitat is 500kg, than the
sphere could support about 1.5 people per square kilometer. On a sphere with
a radius of 1.4 AU, you could only have about 8.8E17 people, a mere 200 million
times the current population. :-)

I'm interested in spheres held apart by electromagnetic forces. This might not
be practical with fixed magnetic fields, but changing fields and active
control might make it possible. I suspect electromagnetism could support
a much greater mass than light pressure alone.

By the way, heating of the center star is a problem with *any* Dyson sphere,
unless the inner surface is kept cold by active pumping of heat. This active
pumping would take up much of the solar energy available. This might be a
fundamental limit on the utility of Dyson spheres.
        John Roberts
        [e-mail]

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

Date: 3 May 90 07:23:59 GMT
From: xavax![e-mail]  (Phillip Harbison)
Subject: Re: Not-so-Silent Running (Was Re: a bunch of other irrelvant things)

In article <[e-mail]> [e-mail] (Henry Spencer) writes:
>>>Have you heard of a Rocket called Saturn V ? There are 2 still available
>>>for your contemplation if you haven't ...
>>     Only two?!?!?!?  Last I checked, there was one at Kennedy, Johnson, and
>>one at Huntsville...

I believe there are two in Alabama.  One is laid out on the ground at the
Space and Rocket Center.  You can walk up inside the huge F1 engines.  The
other is on display at the welcome center on I-65 just south of the AL and
Tennessee border.  I've seen S-Vs on display at both locations at different
times, although its possible they were the same rocket.

The Space and Rocket Center also has examples of most of the other US
rockets and missiles (at least the NASA and Army stuff), including a
Saturn I, Nike-Herc, Nike-Ajax, Little John, etc. and a mockup of the
shuttle assembly.  I also recall they recently got a mockup of the
upcoming space station.  It is a worthwhile attraction to visit if you
are ever down this way.

>The one at Huntsville is a "test article", a pre-production prototype that
>was never considered flight-ready.  (I've seen it, and read the signs on
>it carefully.)  So one can argue that it wasn't a "real" Saturn V.

Marshall Space Flight Center does most of the stress testing.  They take
the prototype, strap it to one monster of a test stand, then shake the
piss out of it.  The prototype is "real", otherwise not much would be
learned by the testing.  Usually, the test vehicle undergoes enough
stress that it wouldn't be prudent to place it in service.  Would you
want to take a flight in the Enterprise knowing it was shaken within a
few milliseconds of mechanical fracture? :-)  Of course some changes
may occur between the test vehicle and the production vehicle, especially
if the testing turns up a problem.

The real fun takes place when one of these babies breaks loose from
the stand with the engines ignited.  Can you say "loose cannon"?  I
knew you could.  This has happened with some smaller prototype missiles.
Kinda hurts the value of real estate near MSFC and Redstone Arsenal,
wouldn't you think? :-)

--
Live: Phil Harbison, Xavax, P.O. Box 7413, Huntsville, AL 35807
Uucp: [e-mail]
Bell: 205-539-1672, 205-880-8951
--
Live: Phil Harbison, Xavax, P.O. Box 7413, Huntsville, AL 35807
Uucp: [e-mail]
Bell: 205-539-1672, 205-880-8951

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

Date: 1 May 90 14:02:29 GMT
From: mcsun!ukc!stl!stc!root44![e-mail]  (Geoff Clare)
Subject: Re: Decompression

In article <[e-mail]> [e-mail] (Alan Duester) writes:
>Note: Locking your nose shut so air doesn't leak out is a tricky thing.
>The first time you try it, you'll also lock your throat if you are
>anything like the normal SCUBA student. We're not used to doing it
>without training. If in doubt, hold your nose and keep the throat open.

I disagree - it's not difficult at all.

Just pretend you're blowing up a balloon.
--
Geoff Clare, UniSoft Limited, Saunderson House, Hayne Street, London EC1A 9HH
[e-mail] (Dumb mailers: ...!uunet!root.co.uk!gwc)  Tel: [phone]

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

Date: 3 May 90 21:24:54 GMT
From: trident.arc.nasa.gov![e-mail]  (Peter E. Yee)
Subject: Two communications satelllites to be launched in May (Forwarded)

Jim Cast
Headquarters, Washington, D.C.                        May 3, 1990
(Phone:  [phone])

Jean Drummond Clough
Langley Research Center, Hampton, Va.
(Phone:  [phone])

Jan Bodanyi
Department of Defense, Washington, D.C.
(Phone:  [phone])


RELEASE:  90-64

TWO COMMUNICATIONS SATELLLITES TO BE LAUNCHED IN MAY


     Two Mulitiple Access Communications Satellites (MACSATs) are
scheduled to be launched by NASA aboard a Navy-owned Scout rocket
on May 9 from Vandenberg Air Force Base, Calif.  The 90-minute
launch window opens at 1:49 p.m., EDT.  The program is sponsored
by the Department of Defense Advanced Research Projects Agency
(DARPA).

     The MACSATs, developed by Defense Systens Inc., will provide
a global store-and-forward message relay capability at UHF
frequencies for a variety of Department of Defense users during
test demonstrations to be conducted this year by DARPA.

     The Scout program is managed by NASA's Langley Research
Center, Hampton, Va.  The 73-feet-long, four stage, solid-
propellant rocket motor launch vehicle is built by the Missiles
Division of LTV Missiles and Electronics Group, Dallas, Texas.
First launched in 1960, Scout has had 98 successful missions in
112 attempts, including 56 successes in 57 launches since 1967.

                             - end -

NOTE TO EDITORS:  The Scout/MACSAT launch will be carried live on
NASA Select television via Satcom F-2R, Transponder 13, C-Band
located at 72 degrees west longitude, frequency 3960.0 MHz,
vertical polorization, audio monaural 6.8 MHz.  Media
representatives may view the launch in the NASA Headquarters
auditorium, 400 Maryland Ave., S.W., 6th floor, room 6104.

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

Date: 3 May 90 15:45:27 GMT
From: sdd.hp.com!samsung!sol.ctr.columbia.edu!IDA.ORG!pbs![e-mail]
Subject: Re: NASA Headline News for 05/02/90 (Forwarded)

In article <[e-mail]>, [e-mail] (Peter E. Yee) writes:
> -----------------------------------------------------------------
> Wednesday, May 2, 1990                Audio Service: 202/755-1788
> -----------------------------------------------------------------
> This is NASA Headline News for Wednesday, May 2...
> (several news items deleted)
>                             ********
> The Apollo 204 spacecraft will be moved from the Langley Research
> Center, May 20 and placed in permanent storage in an abandoned
> missile silo at Cape Canaveral Air Force Station in Florida.  The
> Apollo has been in storage at Langley Research Center since 1967.
>
Is this just the command module (CM) or the whole command & service module
(CSM) assembly?  Being a block I spacecraft this would have to be modified to
reflect later safety standards impossed after the Apollo fire destroyed a
capsule of nearly identical internal design.   However, if this can be done
with resonable effort, Apollo 204 could become a nearly off the shelf Orbital
Transfer Vehicle.  I know from studying my 1/144 scale models that an Apollo
CSM will fit inside a Shuttle cargo bay.  Lift the Apollo into orbit with a
Shuttle and leave it there.  (Perhaps after space station construction is far
enough along to serve as a base of operations.)  Serviced in orbit it could
then ferry payloads from LEO to GEO or even to lunar orbit.

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

Date: 3 May 90 18:03:04 GMT
From: swrinde!cs.utexas.edu!news-server.csri.toronto.edu!helios.physics.utoronto.ca!physics.utoronto.ca![e-mail]  (Christopher Neufeld)
Subject: Re: (How to get rid of) space garbage

In article <[e-mail]> [e-mail] writes:
>In article <[e-mail]>,
>[e-mail] (Christopher Neufeld) writes:
>> In article <[e-mail]>
>[e-mail] writes:
>>>Of course, one would hope that it wasn't in the wrong position when
>>>Hubble came around one orbit, or whoops...
>>>
>>    Well, I chose 80000km for my proposal. It's out of the way of pretty
>> well everything. This scheme wouldn't be workable in LEO
>
>Well, actually I was thinking of accidentally shining the beam down the
>barrel of the HST... there are a number of other satellites out there
>one would not want to do this to, the aiming of this thing would have to
>be carefully worked out.  After all, it doesn't sound as though it would
>be practical to turn it off.
>
   No, it can't be turned off in a reasonable period of time. The beam
isn't a death-ray, though. It has the same intensity as sunlight. The
beam would be seen to come from a point somewhat east of straight up
when you were at local midnight, to make its closest approach to the
Earth just darkside of the day-night terminator to the west of the
observer at local midnight. (By local midnight I mean a person on the
opposite side of the Earth from the Sun).
   This beam always shines into the faces of incoming particles, so the
HST wouldn't be pointed at the beam, since it would also be scooping up
atomic oxygen in that configuration.
   Local overheating in some satellites, which are suddenly lit with
normal intensity sunlight from both sides might be a problem, but they
wouldn't stay in the beam for more than five minutes at a time, and
would pass into the Earth's shadow partway through this interval.

>This is news.  This is your       |    Peter Scott, NASA/JPL/Caltech
>brain on news.  Any questions?    |    ([e-mail])


--
 Christopher Neufeld....Just a graduate student  |  "Spock, comment?"
 [e-mail]              |  "Very bad poetry
 [e-mail]          Ad astra! | captain."
 "Don't edit reality for the sake of simplicity" |

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

Date: 4 May 90 02:56:07 GMT
From: news-server.csri.toronto.edu!clyde.concordia.ca!mcgill-vision!quiche!calvin![e-mail]  (Mark SOKOLOWSKI)
Subject: Manned mission to Venus

I would like to start a new discussion about a manned mission to Venus.
I know that given the inferno that's there, it sounds crazy, but Venus has
many advantages over Mars:
- 3 month flight instead of 9, and lower energy requirements to go there.
- 8 times the mass of Mars, which means that it can trap any spaceship more
  easily than the red planet.
-  Notwithstanding its athmosphere, Venus is the TRUE twin of our Earth, and
   it should be therefore our main target from the cultural point of view.
- The athmosphere of Venus has the same quantity of oxygen as here.

And for those that doubt about my seriousness, I am glad to tell that I
will be the first to volunteer to go there... After all our technology
can enable us to make life bearable even at 900 F and 90 athmospheres

Mark S.
-------

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

Date: 3 May 90 17:21:38 GMT
From: sdd.hp.com!elroy.jpl.nasa.gov!aristotle![e-mail]  (Peter Scott)
Subject: Re: Voyager Update - 05/02/90

In article <[e-mail]>, [e-mail] (Ron
Baalke) writes:
|>
|>
|>                     Voyager Mission Status Report
|>                              May 2, 1990
|>
|>      On April 17, Attitude and Articulation Control Subsystem (AACS),
|> Computer Command Subsystem (CCS), and Flight Data Subsystem (FDS) memory
|> readouts and a playback of PWS and Imaging Science (ISS) data were
performed.
|> (The ISS data consisted of the "family portrait" images lost due to rain
                                                                       ^^^^
|> during the March 23 playback.)  Due to a maser failure at the 70
meter antenna
|> in Spain (DSS-63),[...]
      ^^^^^

The rain in Spain affects mainly antenna gain...?


This is news.  This is your       |    Peter Scott, NASA/JPL/Caltech
brain on news.  Any questions?    |    ([e-mail])

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

End of SPACE Digest V11 #354
*******************