Space & Astronomy/Space and Astronomy (October 1993).iso/mac/TEXT/SPACEDIG/V12_5/V12_571.TXT

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Subject: SPACE Digest V12 #571

SPACE Digest                                     Volume 12 : Issue 571

Today's Topics:
           Re: Pity The Much Abused Shuttle
   Aviation & Space Weekly Alert (was Re: LNLL Inflatable Stations)
           Re: Pity The Much Abused Shuttle
             Re: LNLL Inflatable Stations
               Re:  New Shuttle Engines
           Latest STS 38 orbital elements.
              Magellan Update - 11/16/90
               Re: New Shuttle Engines
            Re: Magellan Update - 11/16/90
              Ulysses Update - 11/16/90
 Re: Summary of responses to "the Ariane V36 failure" (long - sorry)

Administrivia:

    Submissions to the SPACE Digest/sci.space should be mailed to
  [e-mail].  Other mail, esp. [un]subscription notices,
  should be sent to [e-mail], or, if urgent, to
             [e-mail]

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

Date: 16 Nov 90 22:52:07 GMT
From: [e-mail]  (J. Taggart Gorman)
Subject: Re: Pity The Much Abused Shuttle

In article <[e-mail]> [e-mail] (Doug Mohney) writes:
>In article <[e-mail]>, [e-mail] writes
>
>Wrong Bbbbbuck. Shooting out the windshield on a jeep results in lots of glass
>and maybe you might kill someone. If you're Rambo, you dive out of the jeep,
>tastefully tuck-and-roll, then return fire. If the windshield of the shuttle
>gets shot out, and you don't happen to be wearing a space suit, you suck
>vaccuum. Should you be so fortunate enough to get into a space suit,
>Ivan-the-Terrible has now boarded the shuttle to finish the job he started.

  Since this shuttle would knowingly be going into combat, all personel
*would* be in 'suits, because depressurization would be the first thing mean
'ole Ivan would try.

  It looks like we're writing the script for Rambo VII, the one where the
bad Russian space Colonel captures Rambo's one-and-only-friend-and-best-buddy
and take him to his sekret nuklear space battle fortress.  Since NASA doesn't
want to waste a shuttle to save Rambo's one-and-only-friend-and-best-buddy,
good 'ole Rambo sneaks into the evil USSR and steals a Russian shuttle (damn!
forgot the name!  "My mind is going......" - Hal & me) and on the way to the
sekret nuklear space battle fortress, Rambo destroys all of the evil Russian
space forces, and several TIE fighters.
  Sounds like a winning script to  me!  :)

|     John Taggart Gorman Jr.    | "I'm a no rust build up man myself."
|                                |          -Christian Slater
| [e-mail] |             in 'Heathers'

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

Date: 16 Nov 90 23:13:48 GMT
From: mintaka!ogicse!unicorn![e-mail]  (Worth Henry A)
Subject: Aviation & Space Weekly Alert (was Re: LNLL Inflatable Stations)

In article <[e-mail]> [e-mail] (Henry Spencer) writes:
>In article <[e-mail]> [e-mail] (M Parigi) writes:
>>    By the way, how does the need for EVA's compare to that of FREEDOM's?
>
>I would expect considerably less, because there is less external equipment.
>My impression is that LLNL has gone in for putting things inside rather than
>outside, permitting shirtsleeves maintenance on most of it.

    The Nov 12th issue of AvLeak has, among several interesting space
related articles, a summary of the latest FREEDOM redesign goals, included:

    > The biggest single change is the elimination of the longitudinal
      truss and the associated EVA-intensive external experiments and
      other Orbital Replacable Units.

    > The modules will be tightly clustered and the solar & thermal
      radiator arrays will be mounted on a long trailing beam.

    > Besides reducing EVA requirements, this new configuration is expected
      to improve orbital stability and drastically reduce thruster usage.

    > Shuttle construction flights reduced to 18 (@ 4/yr) -- but still
      no interest in ELV's. First element in orbit is still planned for '95.

    > A restructuring of the project budget to something that may be more
      acceptable to Congress. Budget levels in $2.1-2.6B range with
      only small, if any, increases from yr-to-yr (Its at LOT easier to
      maintain a budget at the previous years level than to get a significant
      increase -- perhaps NASA management is finally starting to develop some
      political savvy, its only taken 30 yrs).

    > Changes to the project management structure are "off limits"
      (I suppose NASA feels that the optimal 'pork' distribution has
      already been achieved ;-) ).

    The Nov. 12th issue also has an article on the various non-USA
hypersonic development projects:

   > The contenders include GERMANY-ITALY-SWEDEN, FRANCE, JAPAN
     and British Aerospace-USSR (with growing Brit. gov. interest)

   > Public interest in Seanger(sp?) has already been credited with
     producing a dramatic increase in engineering/science university
     enrollment in Germany.

   > The Japanese plan to progress from scratch, thru a 2-Stage-Stage-To-
     Orbit vehicle, to SSTO in 20 yrs!

     In a related note, the Nov. 5th issue has several articles on the
USA hyperspace-plane combined design and a less-expensive, rocket based,
SDIO proposed alternative.

    These two issues are well worth a visit to your local library or
newstand. If you can't get hold of these issues, then stay tuned for one
of H. Spencer's fine reviews in the coming weeks.

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

Date: 16 Nov 90 21:38:13 GMT
From: newton.cs.jhu.edu![e-mail]  (Paul Callahan)
Subject: Re: Pity The Much Abused Shuttle

In article <[e-mail]> [e-mail] writes:
>One shot from a pistol could disable a Jeep.  Yet for
>some reason Jeeps are useful military vehicles.

Perhaps because they are a bit cheaper than space shuttles (not to mention
more numerous).  It's just a guess...

--
Paul Callahan
[e-mail]

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

Date: 16 Nov 90 06:40:08 GMT
From: munnari.oz.au!mel.dit.csiro.au!yarra!melba.bby.oz.au![e-mail]  (Gregory N. Bond)
Subject: Re: LNLL Inflatable Stations

>>>>> On 16 Nov 90 02:16:10 GMT, [e-mail] (M Parigi) said:
[ re. external maintainence of a spinning space station ]
eempa> You would have to either hook them on to something, or keep good hold of
eempa> things. You would have little chance of retrieving something if it was
eempa> dropped or came unhooked. Doing an EVA on the outside of the spinning
eempa> platform would be like doing repairs on the outside of a building (you
eempa> wouldn't want to fall) as compared to like doing a scuba dive on a
eempa> nonspinning platform.

A Small question of orbital mechanics:

Say the maint crew is on the outside of the spinning station
(replacing AE-31 units, whatever), and they drop a spanner.  It
"falls" away from the station at some speed (the rotational speed of
the station at that point), and takes up an independent orbit around
the earth.

That orbit would be a slightly perturbed version of the station orbit,
due to the (small) delta-v from the spinning station.

Under what circumstances will the orbit of the station and the spanner
intersect, and at what velocity would the collision happen (assuming
no manouvering of the station)?

My guesses: If, at the moment it is dropped, the velocity of the
spanner wrt station is at rightangles (either plane) to the orbital
velocity of the station, then spanner and station should meet twice
per orbit.  Parallel velocities and the spanner will move in or out
and they won't meet.  Inbetween, interpolate!  Max collision velocity:
(2x?) spanners' initial speed wrt station (i.e. very slow, as orbital
collisions go).

So are dropped spanners a serious hazard?

Greg.
--
Gregory Bond, Burdett Buckeridge & Young Ltd, Melbourne, Australia
Internet: [e-mail]    non-MX: [e-mail]
Uucp: {uunet,pyramid,ubc-cs,ukc,mcvax,prlb2,nttlab...}!munnari!melba.bby.oz!gnb

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

Date: 16 Nov 90 21:13:40 GMT
From: usc!wuarchive!cs.utexas.edu!news-server.csri.toronto.edu!utgpu!utzoo![e-mail]  (Henry Spencer)
Subject: Re:  New Shuttle Engines

In article <[e-mail]> [e-mail] (Brett Vansteenwyk) writes:
>I am curious as to how much of a design difficulty it is to have an engine
>operate (well or otherwise) at both sea level and in the vacuum ...

It's not an enormously big deal, but it is a nuisance.  Ignoring some
details, one gets maximum thrust out of a given exhaust stream if it
exits the nozzle at roughly ambient pressure.  This means that a nozzle
optimized for high altitude will be a good bit longer than a sea-level
nozzle, to give the gas more expansion.  An underexpanded nozzle, with
the gas exiting at higher than ambient, results in some loss of thrust.
A badly overexpanded nozzle causes the gas flow to break away from the
nozzle wall before reaching the end, which causes all manner of nasty
turbulence and problems of various kinds.  The SSME nozzles are in fact
mildly overexpanded for use at sea level, for the sake of performance
at high altitude, but not enough to cause major trouble.

Multiple stages, with upper stages ignited only at high altitude, offer
somewhat of a way out of this.  The first stage is still a compromise,
because it finishes its burn in much thinner air than it started in,
but the upper stages can use fairly uncompromised high-altitude nozzles.
People have explored more devious schemes, like variable-length nozzles,
but no real use has been made of them yet.

>... If this is a heavy constraint, why light
>the SSMEs at sea level at all ...

One very important practical reason is that the #1 time for engine trouble
is at ignition.  Lighting the SSMEs on the pad means that the more benign
kinds of engine failures simply cause a pad abort.  There may also have been
some hope that gimballing the SSMEs would suffice for control, and the SRBs
wouldn't need gimballed nozzles, although in fact that didn't pan out.

>By the way, I remember that there is some consideration (or ongoing effort)
>to adapting the RL-10 to operate at sea level.  Is this a good example of
>this sort of design "difficulty"?

In principle, all you need is a shorter nozzle, although you have to think
about things like the effect on the cooling system.  There may be some
issues in ignition, too.
--
"I don't *want* to be normal!"         | Henry Spencer at U of Toronto Zoology
"Not to worry."                        |  [e-mail]   utzoo!henry

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

Date: 16 Nov 90 21:13:34 GMT
From: van-bc!ubc-cs!news-server.csri.toronto.edu!utgpu![e-mail]  (Ted Molczan)
Subject: Latest STS 38 orbital elements.

Here are the first four STS 38 orbital element sets from NORAD:


1 20935U 90 97  A 90320.02911865  .00527620  15306-3  25599-3 0    28
2 20935  28.4678 243.5197 0006234 264.2180  21.9681 16.19915601    01

1 20935U 90 97  A 90320.04174710  .00000532  00000-0  73360-8 0    13
2 20935  28.4687 243.4563 0006495 267.8366  92.1432 16.20314645    19

1 20935U 90 97  A 90320.20017361  .00320873  40597-4  25599-3 0    39
2 20935  28.4683 242.1896 0037834 196.9133   7.8577 16.11416272    39

1 20935U 90 97  A 90320.40850694  .00161290  68898-5  25599-3 0    47
2 20935  28.4646 240.6373 0006560 286.7334  43.3613 16.02355418    67


The fourth set is the most current and reflects the manoeuvre to a
higher orbit that was predicted by AV WEEK.  The orbiter can be
expected to manoeuvre to a slightly lower orbit, shortly after
payload deployment, which is expected sometime today.

Although we now have precise elements for the orbiter, there remains
much for observers to do.  The main task now is to try and observe
the payload.  If it is an imaging reconnaissance satellite, as
reported by AV WEEK, and if past practice is followed, then it will
remain in its deployment orbit for about 7 days, and then manoeuvre
to its operational orbit.

All shuttle and payload observation reports are welcome.

--
Ted [e-mail]

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

Date: 16 Nov 90 23:33:53 GMT
From: mintaka!think.com!sdd.hp.com!elroy.jpl.nasa.gov!jato!mars.jpl.nasa.gov![e-mail]  (Ron Baalke)
Subject: Magellan Update - 11/16/90


                         MAGELLAN STATUS REPORT
                           November 16, 1990

     The Magellan spacecraft is now performing nominally in mapping mode
after experiencing its third loss-of-signal incident yesterday morning.  It
has just completed its 344th mapping orbit.

     Shortly after 9:00 AM PST yesterday, the spacecraft failed to return to
Earth communications after the mapping pass of orbit #825.  The S-band signal
was reacquired about 40 minutes later, and signal level indicated that the high
gain antenna was off Earth point by 1-1/2 to 2 degrees.  The X-band signal
required for radar data playback could not be acquired.

     Engineering telemetry indicated that the control system had detected a
"heartbeat loss" similar to the incidents in August.  The spacecraft had
switched some components, such as the gyros and the Input/Output unit, but was
continuing to execute its command sequence.  The next three star calibrations
were rejected because the one to three degree corrections would be greater than
the limit set within the attitude control system.

     At 3:19 PM PST, attitude updates were sent to the spacecraft to correct
the antenna pointing and mapping was resumed at 6:46 PM.  The quick recovery
from this loss of signal incident demonstrates the contingency plans which were
developed as a result of the earlier incidents.  In August, mapping was
delayed for at least 15 days.  Today, mapping was resumed after 9.75 hours,
with a loss of only 3 orbits.

     Stephen Saunders, Magellan's project scientist, provided images and text
for a special pictorial on Magellan to be published in the January Astronomy
Magazine.
      ___    _____     ___
     /_ /|  /____/ \  /_ /|
     | | | |  __ \ /| | | |      Ron Baalke         | [e-mail]
  ___| | | | |__) |/  | | |___   Jet Propulsion Lab | [e-mail]
 /___| | | |  ___/    | |/__ /|  M/S 301-355        |
 |_____|/  |_|/       |_____|/   Pasadena, CA 91109 |

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

Date: 16 Nov 90 17:59:07 GMT
From: eagle![e-mail]  (Dave Hall (Sverdrup))
Subject: Re: New Shuttle Engines

In article <[e-mail]>, [e-mail] (Greg Cronau) writes...
>
>I can understand why reviving the Saturn program would be damn near impossible,
>but what problems were encountered with reviving just the F-1 engine program?

In addition to lost documentation and tooling costs, two areas I am aware of
are:

1) Air pollution. The F-1 burns LOX and kerosene, producing a smoky hydrocarbon
exhaust. Not popular with environmentalists, especially in S. California where
the Rocketdyne test labs are located.

2) F-1 production test facilities were located in the San Fernando valley
(turbopumps at Rocketdyne/Santa Susana) and Edwards AFB (full-up
engine tests). These
facilities are way past the inactive stage - they have been either torn
down or become completely derelict. You are talking 100's of millions of
dollars (IMHO) to refurbish them.

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

Date: 17 Nov 90 01:46:10 GMT
From: mintaka!think.com!sdd.hp.com!elroy.jpl.nasa.gov!wciu!abode![e-mail]  (Eric C. Bennett)
Subject: Re: Magellan Update - 11/16/90


I guess this may be considered a 'dumb' question, but, what is the mission
objective (other than the obvious, i.e. mapping Venus) of the Magellan
spacecraft. In other words, what does the science community hope to learn
by mapping Venus?

Eric
--
     Eric C. Bennett     uucp: {elroy|cit-vax}!wciu!abode!eric
     El Monte, Ca    Internet: [e-mail]

If you can read this you aren't looking through the hubble space telescope!

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

Date: 17 Nov 90 06:28:45 GMT
From: uakari.primate.wisc.edu!sdd.hp.com!elroy.jpl.nasa.gov!jato!mars.jpl.nasa.gov![e-mail]  (Ron Baalke)
Subject: Ulysses Update - 11/16/90


                        ULYSSES STATUS REPORT
                         November 16, 1990

     At the end of yesterday's science operations, a maneuver was performed
on the Ulysses spacecraft to increase the spacraft's spinrate from 5 to 5.1
rpm and measure the effect on the nutation motion.  The increased spinrate
did slightly decrease the nutation, and further analysis will be required
before any more actions are taken.  Today's activities includes the
switch-on of the Solar Wind Plasma instrument and a mode change on the Solar
Wind Ion Composition instrument.
      ___    _____     ___
     /_ /|  /____/ \  /_ /|
     | | | |  __ \ /| | | |      Ron Baalke         | [e-mail]
  ___| | | | |__) |/  | | |___   Jet Propulsion Lab | [e-mail]
 /___| | | |  ___/    | |/__ /|  M/S 301-355        |
 |_____|/  |_|/       |_____|/   Pasadena, CA 91109 |

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

Date: 17 Nov 90 19:55:39 GMT
From: mentor.cc.purdue.edu!noose.ecn.purdue.edu!en.ecn.purdue.edu![e-mail]  (Philippos A. Peleties)
Subject: Re: Summary of responses to "the Ariane V36 failure" (long - sorry)

Could water injection into the combustion chamber have the same
effect as that for jet engines, i.e., increasing the gas density?
(I have seen something to this effect in the Rolls-Royce book
"The jet engine" but I am not sure about the details since I don't
have it with me).


Philip Peleties
--


I speak for myself, I think for myself, I work for myself ... but I don't want
to play by myself ... so bring your toys and let's share ...

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

End of SPACE Digest V12 #571
*******************