Space & Astronomy/Space and Astronomy (October 1993).iso/mac/TEXT/SPACEDIG/V16_5/V16NO542.TXT

Internet Message Format | 1993-07-13 | 12KB

Date: Fri,  7 May 93 05:50:39
From: Space Digest maintainer <[e-mail]>
Reply-To: [e-mail]
Subject: Space Digest V16 #542
To: Space Digest Readers
Precedence: bulk


Space Digest                Fri,  7 May 93       Volume 16 : Issue 542

Today's Topics:
        Another SF Irritation RELIEVED! Doctor Who vindicated.
                          HST Orbit Reboost
             HST Servicing Mission Scheduled for 11 Days
                       Long term Human Missions
           Science Fiction (was Re: STS-1 DISASTER/COVERUP)
                     Shuttle Landings in Florida
              Space Station Redesign, JSC Alternative #4
             Visas for astronauts after an abort (2 msgs)

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

Date: Fri, 7 May 1993 03:29:05 GMT
From: Aaron 'Wigs' Wigley <[e-mail]>
Subject: Another SF Irritation RELIEVED! Doctor Who vindicated.
Newsgroups: sci.skeptic,sci.space

Richard A. Schumacher ([e-mail]) wrote:
: This "reverse the polarity!" crap always bugged the hell out of me, too,
: until I found an actual, live, real-life example of it working! I quote
: from Aviation Week and Space Technology for 2 July 1990, page 25:

According to a HP-48 calculator owner, the best way to totally reset the
calculator is to put the batteries in backwards. It works by forcing the
capacitors to discharge much faster (instantly compaired to waiting for
up to an hour).

: ! Once again, life imitates art.

The Wigs of Oz,
Aaron Wigley
[e-mail]

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

Date: 4 May 1993 10:34 EST
From: David Ward <[e-mail]>
Subject: HST Orbit Reboost
Newsgroups: sci.space

I'm rethinking my MTTDFSR (Mean time to Deorbit from STS Release).
Earlier, I thought 5 years was an approximate number, based on SMM,
LDEF, and the current GRO orbit.  However, I failed to consider that
all three drag periods occurred during Solar Max.  Since we're
on the downside of the solar activity curve, the drag-down may not
be as quick as I anticipated (7 years?--beginning of next cycle).
However, that _still_ might be too fast, if there's a major delay
in the shuttle program, such as another accident.

Just doing some flame control...

David W. @ GSFC

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

Date: 4 May 1993 10:21 EST
From: David Ward <[e-mail]>
Subject: HST Servicing Mission Scheduled for 11 Days
Newsgroups: sci.space,sci.space.shuttle,sci.astro

In article <[e-mail]>, [e-mail] writes...
>
>If it has no propulsion system, how does it maneuver itself?  I don't think
>viewing targets are chosen by it constantly "staring" at a particular azimuth
>and waiting for the object to come into view... :-)
>_______________________________________________________________
>Harvey Brydon         | Internet:   [e-mail]
>Dowell Schlumberger   | P.O.T.S.:   [phone]
> There is no such word as "Irregardless".  Or "Degradate".

Like most other spacecraft, HST has a set of reaction wheels which turn
electrical energy into angular momentum.  As the wheels spin one way, the
spacecraft spins the other in order to conserve momentum.  HST is a
zero-momentum spacecraft, such that the angular mometum held in spacecraft
rate, wheel rate, and gyroscopic effects is held near zero via constant
magnetic torque interaction with Earth's magnetic field.  This "magnetic
unloading" dumps momentum added to the spacecraft system via drag torque,
gravity-gradient torques, etc.

Mail me a note at my e-mail if you'd like more info.  I'm sorry if this
isn't the clearest explanation in the world, but it'll give the basic
concept.

BTW--regarding the HST reboost--ask the SMM scientists who saw their
spacecraft de-orbit in 1989 (~1 year before Solar Max) whether or not
reboosting HST when you get a chance is a good idea.  It may not seem
like there are orbit problems now, but the mean-time-to-deorbit-from
-STS-release (MTTDFSR) appears to be about 5 years, based on LDEF, SMM,
and extrapolating GRO's current reboost from 350 km.

David W. @ GSFC
[e-mail]

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

Date: 4 May 1993 23:12:46 -0400
From: Pat <[e-mail]>
Subject: Long term Human Missions
Newsgroups: sci.space,sci.space.shuttle,sci.astro

Maybe you should invest in land in the isle of wight.

I was just seeing who would catch the reference.

pat

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

Date: Thu, 6 May 1993 12:52:37 GMT
From: "Bruce T. Harvey" <idsssd!bruce>
Subject: Science Fiction (was Re: STS-1 DISASTER/COVERUP)
Newsgroups: sci.space

in article <[e-mail]>, [e-mail] says:
> IMPORTANT-INFO:

Not.

Well, we know by the control-Z at the end of the article that the poster
is using either a DOS or a CP/M machine.  If it weren't for the disk
space used, I'd enjoy the reading.  However, at this point, I'd like to
see some new chapters in this fiction, as all of this is old hat, now.
Either publish the science fiction or move on to a different genre.

"No matter how hard you try, ya just can't train them nose hairs!" -Don Martin

--
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Manager Appli. Devlopmt.::  INTERNET:     wb3ffv!idsssd!bruce%uunet.uu.net@...
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[phone] x315, x352:: SnailMail: 222 Schilling Cir.,Hunt Valley, MD 21031
::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::

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

Date: Fri, 7 May 1993 01:17:18 GMT
From: Henry Spencer <[e-mail]>
Subject: Shuttle Landings in Florida
Newsgroups: sci.space

In article <[e-mail]> [e-mail] (Claudio Oliveira Egalon) writes:
>When the Shuttle returned to flight, there was some
>talk that landing the Shuttle in Florida was not as
>safe as landing in California so, I am wondering if
>NASA has already ironed out  these safety concerns
>since the last few missions have landed in FL or is
>NASA just compromising safety to save money???

Both.

There have been a number of changes that have generally made landing at
the Cape safer than it was.  On the other hand, landing at Edwards is
always going to be safer, if only because the weather is more predictable
and there is (usually) a better choice of runways.

Whether landing at Edwards makes enough of a difference to justify the
extra cost is a more subtle question.  In any realistic flight program,
you *always* compromise safety to save money, because there is *no limit*
to how much you can spend making the thing a little bit safer.  Sooner
or later, you have to say "that's enough" and fly.

Personally, in this case I suspect that operational expediency is being
given a bit more weight than it really should get.  At eight flights a
year, I don't think it would cripple the program to land at the Cape
only when Edwards is unavailable... and that would be a better policy.
--
SVR4 resembles a high-speed collision   | Henry Spencer @ U of Toronto Zoology
between SVR3 and SunOS.    - Dick Dunn  |  [e-mail]  utzoo!henry

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

Date: Thu, 6 May 1993 18:27:52 GMT
From: Jay Thomas <[e-mail]>
Subject: Space Station Redesign, JSC Alternative #4
Newsgroups: sci.space

In article <[e-mail]>, [e-mail]
(Andy Cohen) wrote:
>
> In article <[e-mail]>, [e-mail] (Dave
> Michelson) wrote:
> >
> > In article <[e-mail]> [e-mail] (Michael F. Santangelo) writes:
> > >[e-mail] (David B. Mckissock) writes:
> > >
> > >...text of options "A" and "B" deleted...
> > >
> > >>Option C - Single Core Launch Station.
> > >>This is the JSC lead option. Basically, you take a 23 ft diameter
> > >>cylinder that's 92 ft long, slap 3 Space Shuttle Main Engines on
> > >>the backside, put a nose cone on the top, attached it to a
> > >>regular shuttle external tank and a regular set of solid rocket
> > >>motors, and launch the can. Some key features are:
> > >>  - Complete end-to-end ground integration and checkout
> > >>  - 4 tangentially mounted fixed solar panels
> > >>  - body mounted radiators (which adds protection against
> > >>    micrometeroid & orbital debris)
> > >>  - 2 centerline docking ports (one on each end)
> > >>  - 7 berthing ports
> > >>  - a single pressurized volume, approximately 26,000 cubic feet
> > >>    (twice the volume of skylab).
> > >>  - 7 floors, center passageway between floors
> > >>  - 10 kW of housekeeping power
> > >
> > >Somehow I have a strange attraction for this idea (living in
> > >a modular home maybe has altered my mind).  The only thing
> > >that scares me is the part about simply strapping 3 SSME's and
> > >a nosecone on it and "just launching it."  I have this vision
> > >of something going terribly wrong with the launch resulting in the
> > >complete loss of the new modular space station (not just a peice of
> > >it as would be the case with staged in-orbit construction).
> >
> > I certainly like this "Option C"...  It's much more like the original
> > Phase B studies from the early 1970's.  Good stuff!
>
> This is actually more like the stuff from Phase A and MOL....Phase B ended
> with a "Power Tower" approach....
>
> It's also VERY expensive in terms of upfront development costs....so all
> you get is a redistribution of costs from the shuttle flights to the
> contractors who build it.

Its not so expensive. It is a shuttle derived heavy lift viechile. The
shuttle is developed. Secondly, its a cylinder, its not to hard to set up.


However, why not use this as a base. Keep the ET attached. Eventually you
can turn that into a truely huge station.

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

Date: 7 May 93 03:58:25 GMT
From: "David M. Faubert" <[e-mail]>
Subject: Visas for astronauts after an abort
Newsgroups: sci.space

>>I have a question that has been ringing in my
>>head for a while. What if after a launch, there is
>>one of these nasty aborts and the Shuttle has
>>to land in a foreign country (Spain or Morroco).
>>Do the astronauts need a visa for staying there
>>or NASA has some kind of special arrangement
>>with the governments of these countries???

In the short time the astronauts are performing an emergency landing they
must fill out a landing card and state the purpose of their visit. Usually,
this will make customs that much less painful for officials and astronauts
alike.


Dave

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

Date: 6 May 93 20:45:32 GMT
From: Vernon K Lindsay <[e-mail]>
Subject: Visas for astronauts after an abort
Newsgroups: sci.space

G. Harry Stine wrote an SF novel called _Shuttle Down_.  It is about a
shuttle launched from Vandenburg having a main engine failure.  The only
possible landing site is Easter Island.  The unexpected need for Chilean
visas was treated as a political problem and the politicians handled it
with a lot of hand waving and averted eyes.

The main part of the story involves the logistics of bootstrapping
shuttle-style technology into a tropical paradise to get it on the back of
a 747 and returned home.

Vern Lindsay

--
"The meek shall inherit the Earth, the rest will inherit a Universe." A. Bond
Internet: [e-mail]                                GEnie: VKLINDSAY

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

End of Space Digest Volume 16 : Issue 542
------------------------------