Space & Astronomy/Space and Astronomy (October 1993).iso/mac/TEXT/SPACEDIG/V12_5/V12_570.TXT

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Subject: SPACE Digest V12 #570

SPACE Digest                                     Volume 12 : Issue 570

Today's Topics:
           Re: Pity The Much Abused Shuttle
          Re: CRAF/Cassini Update - 11/09/90
               ELV Launch Loads
             Re: LNLL Inflatable Stations
          Re: Spectacular event over Europe
             Galileo Update #2 - 11/16/90
           Re: Pity The Much Abused Shuttle

Administrivia:

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

Date: Fri, 16 Nov 1990 13:00-EST
From: [e-mail]
Subject: Re: Pity The Much Abused Shuttle

In regards to the comments by hydra!francis (Francis Vaughan):

> Just how proof to an air launched guided sat-killer missile do you think
> the shuttle is? Sitting duck is the term that comes to mind. It can't even
> run.
>
> At boarding range a high velocity rifle could cripple the shuttle in
> a minute. Just loose a few of those nice tiles in critical places and
> its a goner on reentry. Let alone what would happen if you disabled
> any of the host of critical systems. You could nearly kill the shuttle with
> a slingshot and a well aimed rock.

Your "unable to run" argument is fallacious; putting propellant in the
cargo bay and carrying it into orbit would make the shuttle extremely
maneuverable.

I think you're overestimating the shuttle's vulnerability to light arms;
I doubt a burst from an uzi would do any serious damage.  But in any
case, doesn't your vulnerability argument apply to a Jeep too?  Jeeps
are unarmored.  One shot from a pistol could disable a Jeep.  Yet for
some reason Jeeps are useful military vehicles.

> " Is the satelite in the enemy shuttle cargo bay Igor?"
>
> "Yes Ivan"
>
> "Activate the self destruct Igor"

It would certainly be prudent to disable or jam an enemy satellite's
communications facilities before bringing it aboard.

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

Date: 16 Nov 90 18:27:37 GMT
From: usc!cs.utexas.edu!news-server.csri.toronto.edu!utgpu!utzoo![e-mail]  (Henry Spencer)
Subject: Re: CRAF/Cassini Update - 11/09/90

I wrote:
>...not a good place for solar power.  You have the usual annoying problem
>of it being night half the time, but the real killer is the dust storms,
>which can cut surface illumination to nearly zero for months at a time.

Some correspondence with folks in a position to know indicates that the
latter is a bit of an overstatement.  There is still a fair bit of light,
as it turns out, although it may well be inadequate for viable solar power.
--
"I don't *want* to be normal!"         | Henry Spencer at U of Toronto Zoology
"Not to worry."                        |  [e-mail]   utzoo!henry

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

Date: 14 Nov 90 02:59:55 GMT
From: swrinde!zaphod.mps.ohio-state.edu!usc!elroy.jpl.nasa.gov!zardoz.cpd.com!dhw68k!ofa123![e-mail]  (Wales Larrison)
Subject: ELV Launch Loads


   Allan, you had asked for typical launch loads for different
launch vehicles.  The following data was produced from the vehicle
"User Handbooks" for a project looking at launching a payload on
different vehicles.
   Launch vehicle vibration induced accelerations are combined with
launch vehicle steady state accelerations to produce spacecraft
design load factors (i.e., accelerations that must be considered for
spacecraft structural design).  These load factors are a function of
both launch vehicle characteristics and spacecraft dynamics.
Therefore it is necessary to design the spacecraft so the dynamic
coupling between spacecraft and launch vehicle low frequency modes
is avoided.  Minimum lateral mode frequencies should be above 10 Hz.
Minimal axial mode frequencies differs for all ELVs (I didn't want
to transcribe several tables) and varies from 15 Hz for the Atlas to
31 Hz for the Ariane. Note the following data includes no design
margins.  A margin of 1.4 is typical for design purposes. (Negative
indicates compression in axial loads - units in standard G's)
                          Axial           Lateral
   Atlas                  -6/+2           -2/+2
   Titan III              -7/+3         -2.5/+2.5
   Titan IV             -6.5/+3         -3.5/+3.5
   Delta II             -6.5/+0          -2.5/+2.5
   Ariane IV              -7/+2.5        -2.5/+2.5
   Proton                 -4/0             -3/+3
   Shuttle                -3/+0          -1.0/+1.0
   Shuttle Emergency    -3.5/+2.0        -3.7/+3.7  [1]

  Note [1].  Shuttle emergency lateral loads are driven for
emergency landings - assuming a heavy orbiter "slapping" down hard
on its landing gear and slamming on its brakes.  Normal, measured
landing G's are usually less than 0.5 G lateral and axial.
   Note [2].  ELVs also have to design to typical "pyro shock" load
of1500-2500 G/sec which occurrs when the explosive bolts on the
payload shroud separate, and more severely, when the pryo separation
devices go off to separate the payload from the ELV.  Shuttle
payloads typically use a spring system for separation from the
vehicle (IUS, PAM) or electrically driven latches (LDEF, Space
Telescope, SPAS, etc), or a combination of the two.  Shuttle pryo
shock levels during ascent are in the vicinity of 500 G/sec or less
from SRB and ET separation, which are intentionally attenuated or
dissipated through the structure.

    Last set of random comments.  You could probably use an ELV for
launch, assuming you had a trained, willing and well-conditioned
young crew, and equipped the ELV with a launch escape tower. F-16
pilot trainees are centrifuge tested to 6 Gs for a period of a few
seconds, so 8 G's or so should be tolerable for few minutes ( Just
don't ask them to do much for an while afterwards....)
    Does anyone remember the loads imposed by the Apollo launch
escape system?  I remember the Gemini had very high-G ejection seats
(they were rumored to be a guarantee of back injury if used - and
were only to be used if the choice was quick death rather than slow
death).  How about the Mercury escape system loads?  Soyuz?
    Also, does anyone have any particulars on the "Little Joe"
program at White Sands which qualified the Apollo launch escape
system?  I seem to remember about a half-dozen or so suborbital
tests, including several failures.  Anybody have costs of that?
----------------------------------------------------------------
Wales Larrison                        Space Technology Investor




--
Wales Larrison
Internet: [e-mail]
Compuserve: >internet:[e-mail]
--------------------------------------------------------------------------

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

Date: 16 Nov 90 19:29:48 GMT
From: rochester!sol![e-mail]  (Brian Yamauchi)
Subject: Re: LNLL Inflatable Stations

In article <[e-mail]> [e-mail] ("Allen W. Sherzer") writes:
   In article <[e-mail]> you write:
   >>>You would have little chance of retrieving something if it was
   >>>dropped or came unhooked.

   >>Depends on how valuable it was. I'm sure hand tools would be left but
   >>astronauts would be retrieved.

   >Correct me if I'm wrong, but the astronauts (and tools) would be
   >awfully hard to catch up to to bring back.
   >
   >[calculations showing astronaut flying away at 50ft/sec deleted]

   These numbers look good to me. I guess we will need to tie him to
   the ladder :-).

I suppose you could use clamps like the ones mountain climbers use to
attach themselves to their lines.  Of course, it would still be
possible to fall while moving.

   I was thinking we could save weight by using an
   umbilical to connect the astronaut to the life support system. Perhaps
   we can make the umbilical strong enough to support him/her should
   they fall off.

My guess would be that such an umbilical would be much too cumbersome.
You would also have to worry about getting the line snagged on
something and developing a tear.

   >I really do like the idea of a spun station, but either:
   >      a) despin the station for EVAs or
   >      b) give the astronauts MMU's to get back!

   I think MMU's would be out of the question. They would weigh too
   much at the lower levels. Also, MMU's require too much maintenance.

   How about bungey cords like the kind they use to jump off bridges?

Yow!  All sorts of bad cartoon images spring to mind :-).  The
astronaut playing "snap the whip" with the station (and losing).  The
astronaut being slammed from one module to another like a giant paddle
ball.  The astronaut's cord getting tangled around the hub and the
astronaut spiraling in, in smaller and faster circles until *SPLAT*.

A better idea might be to use something like the EVA Retriever being
developed for Freedom.  This is a robot which is designed to pick up
things that fall off the station -- like tools and astronauts.  The
advantage is that it can be deployed immediately to fetch the target
-- you don't have to wait for another astronaut to suit up.  It uses a
modified MMU, but at least you only need one, and weight is not a
factor since (1) it's a robot and (2) it can stay at the hub until it
is needed.
--
_______________________________________________________________________________

Brian Yamauchi                University of Rochester
[e-mail]        Computer Science Department
_______________________________________________________________________________

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

Date: 16 Nov 90 11:24:31 GMT
From: mcsun!unido!mpirbn![e-mail]  (Daniel Fischer)
Subject: Re: Spectacular event over Europe

In article <[e-mail]> [e-mail] writes:
>A spectacular event occurred on Nov. 5, around 18h UT (19h local time) over a
>large part of western Europe.  Something similar to a big meteorite or
>satellite atmospheric reentry has been observed by thousands of people [...]
>Could someone with connection to NASA, NORAD tells if the satellite hypothesis
>can be rejected ?  Such a large orbiting object should have been tracked.[...]

It *was* a reentry: NORAD has distributed the news that the event was caused by
the reentry & burnup of the upper stage of the rocket that carried the Soviet
comsat GORIZONT 21 into orbit on 3 October. Experienced observers on the ground
had guessed that fact already from the long duration of the phenomenon, 2 to 3
minutes: even a really big meteor (like the one from 1972 or the recent Euro-
meteor from Sept.1986) crosses the sky in a few seconds.

  [Sources: communication with D.Heinlein, Europ. Net for Meteor Cameras + AP]

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

Date: 16 Nov 90 21:55:14 GMT
From: csus.edu!wuarchive!usc!elroy.jpl.nasa.gov!jato!mars.jpl.nasa.gov![e-mail]  (Ron Baalke)
Subject: Galileo Update #2 - 11/16/90


                          GALILEO STATUS REPORT
                            November 16, 1990

     As of noon (PST) Thursday, November 15, 1990, the Galileo spacecraft is
11,584,870 miles from the Earth and traveling at a heliocentric speed of
60,140 miles per hour; distance to the Sun is 101,784,750 miles (1.09 AU).
Round trip light time is 2 minutes, 8 seconds.

     The sequence commanded flushing maneuver is in process as planned.  This
is the 21st flushing maneuver executed since launch. Later today the
spacecraft will execute a sun pointing maneuver of approximately 12.5 degrees.

     A non-interactive command was sent on November 9 to reset the EPD
(Energetic Particles Detector) LEMMS detector threshold to its normal low
setting.  The previous day, the threshold was increased in response to high
noise counts.  Subsequent monitoring of the detector performance indicated
proper operation and allowed a safe return to the lower threshold setting.

     A special EUV (Extreme Ultraviolet Spectrometer) memory readout was
performed on November 10 in response to anomalous operation observed after
commanding the instrument to the encounter mode.  The MRO (Memory Read Out)
revealed two bits of a single byte were corrupted.  The memory corruption is
similar to that observed during last December's 4-day science checkout
although at a different memory location.  The latest anomaly was recreated
and verified on the EUV simulator at the University of Colorado.  The cause
of this EUV anomaly and the previous December anomaly is being investigated
vigorously.  Commands were sent on November 13 to "patch" the corrupted
memory location and reset it to its proper state compatible with Earth
encounter data collection and proper instrument operation was restored.

     A NO-OP command was sent on November 12 to reset the Command Loss Timer
to 216 hours, the planned value for this mission phase.

     The TCM-7 (Trajectory Course Maneuver) sequence memory load was
successfully transmitted to the spacecraft on November 12.  The spacecraft
properly executed the maneuver on November 13.  The maneuver was comprised of
one axial segment and one lateral segment.  Spacecraft performance
throughout the maneuver activity was excellent.  The RPM (Retro Propulsion
Module) tank pressure and thruster temperatures were near predicted levels;
temperatures were similar to those observed in TCM-6.  No spin rate correction
was required between the axial and lateral burn segments or at the end of the
maneuver activity.  Attitude pointing perturbation was minimal beginning at
about 5 mrad and growing to almost 8 mrad after the axial segment.  This
pointing error was corrected with a sequence planned pointing correction to
near 0.5 mrad.  The lateral burn segment produced about 0.8 mrad of attitude
pointing perturbation, well below the 2 mrad threshold, and consequently the
sequence planned pointing correction was not performed.  Preliminary radio
frequency navigation data indicates an axial and lateral overburn of about one
percent which is near pre-maneuver execution predictions.

     Four delta DOR (Differential One-way Ranging) navigation activities were
completed this week - two on November 12 and two on November 15.  The
delta DOR activities were successful.  A total of 23 of the planned 27 delta
DOR activities are complete; 19 were successful.

     The PPR (Photopolarimiter Radiometer) instrument was powered on November
14.  Instrument operation is normal; power and thermal profiles are within
predicted levels.  The PPR calibration scheduled for this morning was completed
as planned.  There were no unexpected events; data is being analyzed.

     The AC bus imbalance measurement dropped about 2 DN (.4 volt) and is
stable near 48.2 volts.  DC bus measurement is presently reading about 2 volts.
Both AC and DC changes occurred during periods of no spacecraft load
switching.  Very little (1-2 DN) AC/DC bus measurement change was observed
during the TCM-7 execution.  All other power-related and spacecraft telemetry
measurements are normal.

     The final Project GDS (Ground Data Systems) test for Earth 1 was
successfully completed with the Canberra 34 meter and 26 meter stations on
November 13.  A key objective was met with the successful test of the probe
data flow from the tracking station to the Probe Flight Operations Equipment
(PFOE) in the Galileo Mission Support Area (MSA).  This link is required to
support the Probe checkout scheduled for December 4th.  GDS testing has now
validated all GDS functions required for Earth 1 support.

     The DSN (Deep Space Network) and Project Flight Team personnel
participated in a "walk-through" rehearsal of the Earth Closest Approach
(ECA) operations on November 15th.  During the review several minor changes
to the sequence of events were suggested and accepted by the Flight Control
and Support Office.  This walk-through will be repeated next week.

     The LGA-2 (Low Gain Antenna-2) retraction and HGA (High Gain Antenna)
deployment reviews were held on November 14 and 15, respectively.  No
concerns/discrepancies were identified by the review board between expected
flight conditions and ground test data.  Expected flight conditions are well
within the ground test database.
      ___    _____     ___
     /_ /|  /____/ \  /_ /|
     | | | |  __ \ /| | | |      Ron Baalke         | [e-mail]
  ___| | | | |__) |/  | | |___   Jet Propulsion Lab | [e-mail]
 /___| | | |  ___/    | |/__ /|  M/S 301-355        |
 |_____|/  |_|/       |_____|/   Pasadena, CA 91109 |

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

Date: 16 Nov 90 21:02:57 GMT
From: mojo![e-mail]  (Doug Mohney)
Subject: Re: Pity The Much Abused Shuttle

In article <[e-mail]>, [e-mail] writes:

>Your "unable to run" argument is fallacious; putting propellant in the
>cargo bay and carrying it into orbit would make the shuttle extremely
>maneuverable.

And a bigger target. Remember, you *have* to open the cargo bay doors in orbit
(All that internal heat which needs to be radiated. Of course this makes a
wonderful signature for an IR homer missile, personified by several cheap,
light-weight models in your choice of man-portable or luggable by spacecraft).
Now, you could armor your extra propellant tanks (which, by the way, they are
JUST getting qualified to even put into the system), but armor is weight.
Weight is bad if you are putting something into orbit.

>I think you're overestimating the shuttle's vulnerability to light arms;
>I doubt a burst from an uzi would do any serious damage.  But in any
>case, doesn't your vulnerability argument apply to a Jeep too?  Jeeps
>are unarmored.  One shot from a pistol could disable a Jeep.  Yet for
>some reason Jeeps are useful military vehicles.

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.

But, hey, why use GUNS. A couple of handfuls of BBs or gravel (preferably
gravel, it won't show on radar) dropped into the orbital flight path and <poof>
major damage to the system... If you're real lucky, you get a hit on the nice
hydrozene tanks, thereby blowing a big hole in the bird when it goes up and
generally assuring you are going to do some hitchhiking.

>It would certainly be prudent to disable or jam an enemy satellite's
>communications facilities before bringing it aboard.

Sure. So what do you do when the Soviets declare war when you pick up their
satellite? Shuttle orbital flight-paths are carefully tracked by their version
of NORAD, and if one intersects with Spy-Sputnik, followed by Spy-Sputnik
going off-line, don't you think someone might suspect something?

Then the Soviets, determined to ruin your day, launch an SS-9 with ASAT warhead
(or more probably something they have tucked away for a rainy day with solid
fuel) and within 3-4 orbits turn the Rambo-Shuttle into scrap metal.

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

End of SPACE Digest V12 #570
*******************