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Subject: SPACE Digest V11 #323

SPACE Digest                                     Volume 11 : Issue 323

Today's Topics:
          NASA Prediction Bulletins:  Space Shuttle
       Three unconnected thoughts on STS-31 and the HST
              Re: Decompression
     Re: Three unconnected thoughts on STS-31 and the HST
      Re: IMPORTANT MESSAGE for Shuttle Landing Viewers
                Re: Our galaxy
           Re: Space Station Distribution Frequency
                Re: Our galaxy
      Re: Krystall addition to Mir delayed until June 1
       Black Holes Forever! (Was:  Re: Dyson spheres? )
----------------------------------------------------------------------

Date: 27 Apr 90 04:17:16 GMT
From: ncis.tis.llnl.gov!blackbird![e-mail]  (TS Kelso)
Subject: NASA Prediction Bulletins:  Space Shuttle


The most current orbital elements from the NASA Prediction Bulletins are
carried on the Celestial RCP/M, [phone], and are updated several times
weekly.  Documentation and tracking software are also available on this
system.  As a service to the satellite user community, the most current
elements for the current shuttle mission are provided below.  The Celestial
RCP/M may be accessed 24 hours/day at 300, 1200, or 2400 baud using 8 data
bits, 1 stop bit, no parity.

STS 31
1 20579U 90037  A 90116.05462219  .00000000  00000-0  00000-0 0 00023
2 20579 028.4813 221.1360 0002583 316.9075 043.1762 14.84048541000232
HST
1 20580U 90 37  B 90115.92007935 -.00019413  00000-0 -22999-2 0   416
2 20580  28.4631 222.0038 0005784 272.7940  87.2151 14.84112255   202
--
Dr TS Kelso                           Assistant Professor of Space Operations
[e-mail]          Air Force Institute of Technology

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

Date: 25 Apr 90 14:50:19 GMT
From: eru!luth!sunic!mcsun!unido!mpirbn![e-mail]  (Daniel Fischer)
Subject: Three unconnected thoughts on STS-31 and the HST

Now that HST is where it belongs - that was the most dramatic launch ever, with
the exception of STS-26 perhaps - I cannot resist posting some thoughts...:
   a) How could it go up at all?! In AW&ST of 16 March 1987 p.64 it said that
every time something stops the countdown during the final 5 minutes, there will
inevitably be a scrub for this day, because the procedures to check out what
precisely went wrong are so complicated now. So this story was wrong, and NASA
still gan go ahead when they want to?! (Not a criticism, just asking!)
   b) Where did the '14 billion light year' myth originate? I must have heard it
about 20 times yesterday on TV & radio that "til now we could only see for
two billion light years, but now we can see 7 times farther with the HST" -
every few months the media celebrate a new quasar at 15+ billion light years,
and nobody realizes this contradiction. I've found the 'factor of 7' nonsense
even in NASA press kits and brochures -  w h y  must they tell everybody this??
   c) Finally, I'd like to add something to the 'how can we get HST pictures in
machine-readable form?' debate. On 23 Feb 1990 I talked with Benoit Pirenne who
is at the ST European Coordinating Facility, dealing with data distribution. He
told me that - after the 12...18 month priority interval, of course - almost
*everybody* can have all HST data on tape, optical disk etc. *for free*. This
option is open to amateur astronomers and space fans as well as for any
scientist: all you'll need is an account on their computer (at Garching, FRG;
but it should be very similar at Baltimore). And if you just want to browse
through the data catalog, you can even log in as a guest. This is a really
fascinating option, and in late '91/early '92 there might be more HST images
on the net or ftp-able than anybody is thinking about yet...

+- [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 -----+

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

Date: Thu, 26 Apr 90 10:11 EDT
From: [e-mail]
Subject: Re: Decompression
X-Envelope-To: [e-mail]

   In regards to 'breathing space':

   Once you have exhaled what's in your lungs, thus preventing them from
exploding (always unpleasant), you will probably want to prevent the O2
in your arteries from leaving.  In addition is seems a poor idea to
allow the water in your lung tissue to vacuum-boil away.  I suspect that
this would cause a lot of damage.

   The partial pressure of water at room temperature is 25 torr, out of
the 760 torr in one atmosphere.  At body temp I believe it's about 35
torr.  This means that if the pressure is under this exposed water will
boil.  Keeping the mouth open would allow a continuous low temperature
steam to exit the lungs.  (Can you say 'dry mouth'?)  In addition, the
O2 in your blood would be diffusing out as well.

   Were I to be in this situation I would blow out until I had just
about all the air in my lungs exhausted, then close up to prevent my
internal supplies of water and O2 from leaving.  I think that the
pressure generated by ~35 torr of water vapor plus whatever pressure of
diffusing O2 would damage the lungs less than letting the water and
oxygen leave.  If it indeed is not high enough to cause damage such a
tactic would give you more time to act in the vacuum - the rising
pressure in the lungs would slow the diffusion of oxygen from the blood.

   Comments from anyone?

                        Kevin Ryan

Internet: [e-mail]

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

Date: 26 Apr 90 14:27:44 GMT
From: ogicse!plains![e-mail]  (Jeffrey P. Bakke)
Subject: Re: Three unconnected thoughts on STS-31 and the HST

In article <[e-mail]> [e-mail] (Daniel Fischer) writes:
>Now that HST is where it belongs - that was the most dramatic launch ever, with
>the exception of STS-26 perhaps - I cannot resist posting some thoughts...:
>   b) Where did the '14 billion light year' myth originate? I must have heard it
>about 20 times yesterday on TV & radio that "til now we could only see for
>two billion light years, but now we can see 7 times farther with the HST" -
>every few months the media celebrate a new quasar at 15+ billion light years,
>and nobody realizes this contradiction. I've found the 'factor of 7' nonsense
>even in NASA press kits and brochures -  w h y  must they tell everybody this??

Feel free to correct me if I'm wrong but the 2 billion light years represents
the distance that we can 'see' with our current scopes.  This means using
visible light to identify objects.  When hear of 15+billion light year
objects being detected, more than likely it was found by radio telescopes
which operate on wavelengths other than those of visible light.  Radio
waves are not affected nearly as much by the cloud cover and ozone layer
of the earth.

Jeff Bakke
[e-mail]

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

Date: 26 Apr 90 17:13:22 GMT
From: usc!venera.isi.edu![e-mail]  (Paul Raveling)
Subject: Re: IMPORTANT MESSAGE for Shuttle Landing Viewers


In article <[e-mail]>,
[e-mail] (Mary Shafer) writes:
>
> For those of you who will be Official Guests, the Usenet RDV will be
> in front of the black F-18 (the HARV) 30 minutes after the landing.
> See you there.

    Here's a followon thought -- if we all come prepared, we
    could have a USENET picnic breakfast sometime after meeting
    at the F-18.  Considering space available, something like
    beach blankets on the ramp might work better than competing
    for the local picnic tables.  If there are USENETers with
    only hillside (not Official Guest) passes we could find
    a different spot that would be suitable to all.

    I've been thinking about bringing something very slightly
    elegant, but may wind up just bringing coffee and donuts
    ala Twin Peaks.  Maybe "the elegant" will be "damn good
    coffee -- and hot, too!".

    If you have thoughts about this I'd welcome them by email.
    (Mary and Steve Jay have already)


----------------
Paul Raveling
[e-mail]

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

Date: 26 Apr 90 15:06:04 GMT
From: mcsun!ukc!acorn!ixi![e-mail]  (Mike Moore)
Subject: Re: Our galaxy

In article <[e-mail]> [e-mail] (Alan Hepburn) writes:
>In article <[e-mail]> [e-mail] (Garrett A Wollman) writes:
>>
>>Of course, that's cheating.  What we need is a numbering system that's
>>not so geocentric; we should chose some other center (perhaps that
>>hypothetical point 10 kpc away?) from which to base our system...still
>>purely arbitrary, but it would at least free us to speak in less charged
>>terms about our home.
>>
>>
>
>     Actually, I think that referring to Earth as SOL-3 is more
>heliocentric than geocentric.  To be really detached, maybe we
>should refer to it on the basis of our position in the galaxy, or
>something along those lines.
>
>

Wouldn't that be galactocentric?  Einstein was right, relativity is
everything.  So (apart from the maths) why not just assume that we *are*
the centre of the universe, then we can be self-centred and proud of the
fact :-)

Disparate co-ordinate systems are a part of life, on a map we use a grid
system, but for me to tell you where I live I would give you an address
(i.e. I would use a different co-ordinate system) but I _could_ use
_either_ system and you would still understand where I lived so long as
you knew what I was talking about.  Then there is a third system, zip
codes (or postal codes), each defines a specific tract of land, so, you
use your system and I'll use mine, and when we have to communicate we'll
get a computer to do the translating!!:-)

BTW, do satellites have their own internal co-ordinate system, and is this
system different depending whether the satellite is orbiting earth or
travelling between planets?  What about non-ecliptic orbiters?


Mike
--
--------------------------------------------------------------------------
Usual disclaimer.....  etc                        | [e-mail]
True Intelligence is not knowing all the answers, |
it's knowing the right questions.                 |

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

Date: 26 Apr 90 23:35:36 GMT
From: zaphod.mps.ohio-state.edu!usc!cs.utexas.edu!texbell!nuchat![e-mail]  (Steve Nuchia)
Subject: Re: Space Station Distribution Frequency

In article <[e-mail]> [e-mail] (Tom Neff) writes:
>so my question still remains, Why does anyone think 20kHz was ever
>the right way to go?  I am sure there are concrete answers to some

The main argument in favor of it is that you can build a switching
mode power converter without putting a rectifier/filter/inverter
in front of it.  Essentially the whole power system is one big
inverter front end.  You want to run your *converters* at high
frequency so they respond quickly to control inputs and so their
magnetic components can be smaller.  Most of the mass in an electronic
gizmo is transformer iron, followed by packaging, then capacitors,
usually.  The calculation of the amount of iron required is complicated,
but at 60Hz it is outrageous, while at 400 Hz it is merely painful.
At 20 KHz it is well under control, like comparable to the copper
in the windings.  The capacitance required to filter the converter
output also decreases rapidly with frequency.  Big capacitors are
bulky, but their mass is considerable too.

The argument against 20KHz is that you have to do a bunch of
research into how to build converters and switchgear for it,
how to control stray inductances in your wiring, etc ad nauseam.

The argument in favor of 400 Hz is that it is widely used in
aircraft, and a lot of equipment is available off-the-shelf to
run from it.  Even if NASA couldn't bring themselves to fly
off-the-shelf hardware, the manufacturers would be used to
working with it, so one could expect their performance to be
more predictable on custom work.

Similar arguments would apply to 60Hz, but the weight penalty
is pretty severe.  A quick glance in the catalogs shows a
shipping weight of 8 pounds for a 190 Watt 60 Hz transformer.
The power supply in your typical AT clone is rated at 200 Watts
and the whole supply, including case and fan, weighs less than
five pounds.

There is also a great deal of experience with DC, but I wonder
how the voltage was chosen?  Looks suspiciously like sqrt(2)*120,
which is the nominal value for rectified line current.  That's
what you work with before the inverter in a transformerless switching
mode power supply, like the ones in PCs.  160 VDC is higher than
you'd like from a shock hazard standpoint, but I suppose that
48V would increase the mass of copper and/or the copper losses too much.

One argument against DC is that, since the current doesn't reverse
several times a second, your fuses and circuit breakers have a harder
job to do.  This won't be much of a problem at the power levels they
are working at, and even when it is a problem the main penalty is
cost, not mass.

An argument in favor of DC is that there will be no conversion
loss when running from batteries.  If they had used any AC
there would have been losses just getting it onto the bus, which
would have been wasted if the load was resistive.  Of couse they
may decide to *regulate* the DC bus, in which case you get those
losses anyway.

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

Date: 25 Apr 90 19:32:15 GMT
From: hpcc01!hpcuhb!hpindda![e-mail]  (Don Coolidge)
Subject: Re: Our galaxy

>In a related topic, is there any "better" name for our galaxy than "the
>Milky Way"? Something that sounds more like a proper name and is more
>dignified?
----------
We have it from a somewhat reliable source that the Time Lords of Gallifrey
refer to it as "Mutter's Spiral".

If that's good enough for The Doctor, it's good enough for me.

;-)

Only marginally more seriously, isn't that pretty much an accurate English
translation of "galaxy"? So we're left with Sol, Terra, and Galaxy as the
Latin/Greek equivalents of The Sun, The Earth, and The Milky Way.

Names of prominent natural features stick around for millennia. The local
language may change, but the name remains. Folks come to consider it as
just a name after awhile, and they no longer think of the original meaning.
So, "The Galaxy" _is_ "The Milky Way".

An even better example is Mt. Monadnock in New England. Three tongues are
layered here, and the full translation is "Mt. MountainMountain". I like
"Mt. Monadnock" better, but it doesn't mean anything different...


- Don Coolidge

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

Date: 26 Apr 90 15:00:38 GMT
From: manta![e-mail]  (Michael A. Simpkins)
Subject: Re: Krystall addition to Mir delayed until June 1

In article <[e-mail]> [e-mail] (Glenn Chapman) writes:
>
>     On board the Mir space station cosmonauts Anatoly Solovyov and Alexander
>Balandin, now in orbit for 72 days,
>In addition an insulation
>blanket on the Soyuz TM-9 has come free, and is flapping when the station
>moves.  This movement is distracting the station's star trackers used in Mir's
>alignment system and making that problem worse.  Originally it was planned
>that repair materials for the blanket would be sent up with Krystall.
>
>                                                          Glenn Chapman
>                                                          MIT Lincoln Lab
----------------------------------------------------------------------------------------------------------------------------------------------------------------    I guess we all know what they DON'T carry in their tool box! :-)

    Maybe the Shuttle boys and girls can float them a roll on the
    way by.
                "What is dis DUCK tape?!"


                -simpkins-
                P.S. We used to call it racers tape
                    "Good for an extra 20 M.P.H."

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

Date: 26 Apr 90 07:02:30 GMT
From: bigbang.Berkeley.EDU![e-mail]  (George William Herbert)
Subject: Black Holes Forever! (Was:  Re: Dyson spheres? )

In article <[e-mail]> [e-mail] (Patrick Brewer) writes:
>
>    Last I heard (Playboy interview) Hawking has decided the black-holes
>can't exist. And he is now trying to prove it.

Not true. He decided that singularities can't exist, because of violations of
current quantum theory.  Black holes still exist, as far as we can tell :-)


*******************************************************************************
George William Herbert              JOAT For Hire: Anything, Anywhere: My Price
   UCB Naval Architecture undergrad: Engineering with a Bouyant Attitude :-)
-------------------------------------------------------------------------------
"Who?" the man managed.                    Whip me, Beat Me, Make me learn C...
"The Rastafarian Navy," Case said,         ++++++++++ [e-mail]  OR
"...and all we want is a jack into your    ========== [e-mail] OR
custodial system." -neuromancer            """""""" [e-mail]

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

End of SPACE Digest V11 #323
*******************