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Subject: SPACE Digest V10 #186

SPACE Digest                                     Volume 10 : Issue 186

Today's Topics:
                 Re: Pegasus
       Re: NASA Headline News for 10/26/89 (Forwarded)
              Galileo Questions
     Re: how is Voyager gaining speed as it encounters Jupiter ?
     Re: how is Voyager gaining speed as it encounters Jupiter ?
           Condensed CANOPUS - August 1989
----------------------------------------------------------------------

Date: 26 Oct 89 18:07:58 GMT
From: mailrus!sharkey!itivax!vax3![e-mail]  (Allen W. Sherzer)
Subject: Re: Pegasus

In article <[e-mail]> [e-mail] (Bob Slaughter) writes:
>Any word on when the first launch of Pegasus was/will be?

There is a note about it in the current Avation Week. Launch is currently
set for December 7. They are having problems connecting Pegasus with the
B-52.

>Also, could someone point me to a good overview article on Pegasus, with
>design illustrations and other basic info.

There was a good one in a recent (last 8 weeks) Avation Week.

  Allen

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|  You know you have hit bottom when you sleep in a pool of your friends   |
|  vomit because it's warmer then the sidewalk.                            |
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Date: 27 Oct 89 02:05:11 GMT
From: mailrus!jarvis.csri.toronto.edu!utgpu!utzoo![e-mail]  (Henry Spencer)
Subject: Re: NASA Headline News for 10/26/89 (Forwarded)

In article <[e-mail]> NASA writes:
>NASA yesterday awarded a $64 million contract to General Dynamics
>Corporation to launch a government satellite.  The satellite,
>which is a joint venture of NASA and the Air Force, is scheduled
>to be launched in June 1990.  It will mark the first commercial
>launch by General Dynamics and will use an Atlas 1 launch
>vehicle.

Um, it would be too much to ask the *name* or *mission* of this satellite?
--
A bit of tolerance is worth a  |     Henry Spencer at U of Toronto Zoology
megabyte of flaming.           | uunet!attcan!utzoo!henry [e-mail]

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

Date:     Thu, 26 Oct 89 15:38:31 CDT
From: Will Martin <[e-mail]>
Subject:  Galileo Questions

Thanks to Peter Yee for the posting of the STS-34 Press Kit. There's a
lot of good info in there and it answered most of my questions about
Galileo right at the start!

I do have a few minor queries:

1) I seem to recall some traffic on the SPACE Digest some months or even
years back about litium batteries in space-rated hardware. As I recall
the discussion, it seemed to be that lithium batteries were not allowed
in payloads going up in the Space Shuttle, due to the risks of their
exploding or outgassing or doing something else nasty. The Galileo probe,
however, is powered by lithium batteries. I assume nothing else would
give the long 5-year dormancy followed by a brief 75-minute spasm of glory
as the probe executes its brief mission. :-)

Am I recalling the earlier discussion correctly? If so, was the restriction
on lithium batteries only on *commercial* versions? I am assuming these probe
batteries are not "stock" off-the-shelf items but instead specially
constructed custom components designed for this mission, and thus may be made
far safer than ordinary versions. Is this the case?  If so, can anyone
describe briefly how these differ from commercial versions? Are we likely to
see a spinoff from this for very-high-reliability commercial batteries, or
very-safe versions for use in explosive atmospheres or other critical
applications?

2) This is actually much more general than just Galileo-related: the
"T-minus" countdown chart included in the press kit listed a number of
"built-in holds", such as the one at T-27 hours and so forth. Why is the
countdown constructed this way? Why build in a "hold" of 8 hours instead
of just lengthening the countdown period by 8 hours and scheduling the
actions that take place during this hold at the same relative time?
It would appear on the surface that a "hold" should always be an
exceptional condition -- something caused by a problem -- as opposed to
a regular scheduled event expected to occur at some scheduled time.
There must be a good reason for these built-in holds, but I can't figure
it out. I'd appreciate enlightenment on the subject.

3) This is purely speculative -- I've been trying to figure out some
in-flight use for the many pounds of ablative heat shield that burns off
the probe during Jupiter-atmosphere entry. The problem is that it can't
be anything consumable, like maneuvering-thruster fuel, which would be
used during the flight, because that mass has to be there to be burned
off as heat shielding when the probe enters. Also, it has to be dense
and massive and approachng homogeneous, so it will function adequately
as ablative material. So far, the only thing I've been able to think of
is densely-packed electronics embedded in some potting compound. Or
perhaps some really futuristic crystalline mass of computing circuits
based on nanotechnology? (How about an AI that takes measurements
during the flight but then dies a fiery death during the probe entry?
Shades of HAL -- what a motivation to sabotage the mission! :-)

Maybe some sort of entirely-solid-state scanning mechanism to take
detailed star-chart type images during those long lonely years of travel
between slingshot points? Any other ideas?

(I'm sure better minds than I had spent many long hours trying to come
up with some sort of productive use for that otherwise-inert and
extremely-expensive-to-ship weight; anyone from NASA care to post any
notes on what might have been proposed, if anything?

Regards, Will Martin

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

Date: 26 Oct 89 22:55:14 GMT
From: att!drutx![e-mail]  (DL Olson)
Subject: Re: how is Voyager gaining speed as it encounters Jupiter ?

In article <[e-mail]>, [e-mail] (Henry Thomas) writes:
> Could someone explains me spacecraft like Voyager or Galileo can gain speed
> when they encounters Jupiter (resp. Venus)? I suspect it is linked to the
> loss of propellant at perihelie, but I need a clear explanation. Thank you.

It is called the "slingshot effect".  If you have a stone in a sling, each
time you pull the sling around you, the stone picks up speed.  If you pull
it fast enough, the stone will break away from the sling at that increased
speed.

With that in mind, let the planet represent you, its gravitational pull
be the sling, and the spacecraft be the stone.  Since the planet is also
moving in its orbit around the sun, the planet pulls the spacecraft around
with it (kind of like your pulling the stone in the sling around you).

If the spacecraft is pulled along fast enough, it breaks "orbit" at the
increased speed.  The planet actually slows down, because it gives up a
little of its orbital energy to the spacecraft.



David Olson
..!att!drutx!dlo

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

Date: 28 Oct 89 15:55:15 GMT
From: bfmny0![e-mail]  (Tom Neff)
Subject: Re: how is Voyager gaining speed as it encounters Jupiter ?

I must say that in the days when I didn't understand gravity assist,
describing it as the "slingshot effect" (and explaining how a kids'
slingshot works) never helped me understand anything!  The nickname is
fanciful and there's no real connection except that something gets
accelerated.

The easiest explanation is this: When we guide a spacecraft into a
near-miss encounter with (for instance) Jupiter, it falls INTO and
escapes AWAY FROM Jupiter with the same kinetic energy *relative to
Jupiter*; but because Jupiter is moving in its orbit, the net effect
*relative to the rest of the Solar System* is to tack part or all of
Jupiter's orbital velocity onto that of the spacecraft.  By choosing the
proper near-miss trajectory, and optionally by tweaking the motors near
closest approach, we can "apply" this extra momentum to move the
spacecraft someplace specific.

This has been asked ad nauseam recently; I think it goes in FAQ.
--
"NASA Announces New Deck Chair Arrangement For   \_/  Tom Neff
Space Station Titanic" -- press release 89-7654  \_/  [e-mail]

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

Date: 29 Oct 89 19:09:40 GMT
From: frooz!cfa250![e-mail]  (Steve Willner)
Subject: Condensed CANOPUS - August 1989


Here is the condensed CANOPUS for August 1989.  There are 6 condensed
articles and 18 articles by title only.  CANOPUS is copyright
American Institute of Aeronautics and Astronautics, but distribution
is encouraged.  See full copyright information at end.

---------- CONTENTS -- 6 ARTICLES CONDENSED OR IN FULL ----------

NASA AWARDS GRANTS FOR FUTURE EXPLORATION STUDIES - can890801.txt - 8/3/89
SCIENCE OBSERVATIONS SELECTED FOR HUBBLE SPACE TELESCOPE; TELESCOPE
    IS ROTATED FOR SHIPMENT - can890802.txt - 8/3/89
QUAYLE SAYS FLIGHT ACCIDENTS TO BE EXPECTED - can890806.txt - 8/3/89
UNUSUAL CLOUD:  A GAS RELEASE OR A "SMALL COMET" BREAKUP? - CAN890819.TXT -
    8/25/89
LONG PLANETARY "DATA STREAM" ABOUT TO START, KELLER SAYS - can890824.txt -
    8/30/89
------------------------------------------------------------------------

NASA AWARDS GRANTS FOR FUTURE EXPLORATION STUDIES - can890801.txt - 8/3/89

NASA's Office of Exploration has awarded a series of study contracts
to various organizations to provide NASA with ideas, concepts,
devices, systems, trajectories, operations or implementations which
could be applied to furthering human exploration of the solar system.
The 20 winners, selected from 115 proposals submitted in response to
the April 12, 1989, NASA Research Announcement, are located in 12
different states and come from five industry-related firms, two space
support-related organizations, and 13 universities.

SCIENCE OBSERVATIONS SELECTED FOR HUBBLE SPACE TELESCOPE; TELESCOPE
IS ROTATED FOR SHIPMENT - can890802.txt - 8/3/89

162 proposals were accepted following an intensive scientific peer
review of 556 proposals submitted by astronomers from 30 countries.
Approximately 20 percent of the proposals were from member nations of
the European Space Agency, a joint partner with NASA on the HST
project.  Observing time was heavily oversubscribed. During the first
12-month observing cycle {really only the last 5 of the 12 months
were available, though, because of checkout and time for "guaranteed
time observers"}, 11,000 hours of observing time were requested, with
only 1200 hours available.  The average length of an accepted
observation is 10 hours.

To utilize every moment of observing time and hence maximize
efficiency, HST is "over-booked" with accepted general observer
proposals by a ratio of 3:1. One hundred eight accepted proposals are
high priority and represent 90 percent of HST observing time. The
remaining 54 supplemental proposals essentially "fly standby." They
will only be executed if appropriate scheduling opportunities arise.

{The next proposal cycle will have more time available.}

QUAYLE SAYS FLIGHT ACCIDENTS TO BE EXPECTED - can890806.txt - 8/3/89

Vice President Daniel Quayle said that space flight accidents
involving loss of life are to be expected, but should not be a reason
for halting manned space flight.  Quayle spoke to reporters as he
arrived in Huntsville, Ala., for a quick tour of NASA's Marshall
Space Flight Center today.

Earlier in the day the Congressional Office of Technology Assessment
released a report asserting that there is an 88 percent chance of
loosing a Space Shuttle orbiter within the next 40 or so missions.
The report did not say it would be a Challenger-type accident, with
loss of crew, but did say that the orbiter would be so seriously
damaged as to remove it from action.

"I don't necessarily go along with that forecast at all," Qualye
said. "Of course there are risks [in space flight]. Let's face it,
this is a dangerous mission," but added that "it's part of the
American culture to be pioneers....  I don't think that [risk] should
be a reason to shut the door."

When asked by a reporter whether he would like to travel in space,
Quayle said, "There are people who think I'm already there."

UNUSUAL CLOUD:  A GAS RELEASE OR A "SMALL COMET" BREAKUP? - CAN890819.TXT -
8/25/89

Contributed by Patricia Reiff/Rice University

    On the evening of Saturday, August 19, 1989, at 9:30 pm CDT,
I spotted a small (less than 1/2 degree across), very bright cloud.
It was as bright as a typical dense cumulus cloud illuminated by
sunlight; however, the sun had set over an hour earlier.  Since the
sky was otherwise completely cloudless (the Milky Way was visible) I
called it to the attention of my family and friends immediately.  It
expanded and dimmed rather quickly.  By 9:35 it had acquired the
shape of a symmetric, stylized fish or space shuttle (about 1 x 2
degrees) angled about 45 degrees to the horizon with the fins in the
lower left and the nose pointed to the upper right.  It fluctuated in
brightness as it continued to expand and dim.  Examination of the
cloud through 11 x 80 astronomical binoculars revealed no central
object and no striations but a fairly sharp edge all around.  No
sonic boom was heard.  By 9:40 it had expanded to about 2 x 5
degrees, still at 45 degrees to the horizon.  By 9:45 it was
subvisual but still observable through the binoculars, although the
edge was difficult to discern.  By 9:48 it was not distinguishable
against the sky haze at all (the moon, two days past full, was just
beginning to rise).  The object was roughly halfway between Arcturus
and Spica, and did not appear to move.  Our location was roughly ten
miles north of Hockley, Texas (45 miles northwest of Houston).

{more details omitted}

    So what was it?  {many obvious possibilities ruled out} Reiff
would appreciate hearing other ideas or information on this cloud.

 Patricia H. Reiff, Senior Research Scientist
 Internet    [e-mail]   (128.42.10.3)

HIPPARCOS UPDATE - can890821.txt - 8/29/89

ESA officials have stated that the Hipparcos mission should observe
the planned number of stars, but that the accuracy will be lower.
"The Tycho catalog mapping 400,000 stars, and the Hipparcos catalog
giving the positions of 120,000 stars, can still be compiled by the
satellite," said ESA Project Scientist Michael Perryman.

"The precision will be a factor of 10 less than expected. However, we
still hope to achieve a positional accuracy 15 times greater than
from the ground."  Each star probably will be observed only 10 times
rather than 80, and the mission may last only 6 months to two years,
depending on radiation degradation of the solar cells. That rate
should become known in about a month.

"We hope at least to get the positions and magnitudes of stars, if
not the measurement of the parallaxes and proper motions," Perryman
said.  {Unfortunately, it was the parallaxes and to a lesser extent
the proper motions that were the major scientific interest of the
mission.  This is a serious loss.--SW}

LONG PLANETARY "DATA STREAM" ABOUT TO START, KELLER SAYS -
can890824.txt - 8/30/89

A stream of planetary data that will last into the 21st century is
about to begin, NASA Associate Deputy Administrator Sam Keller told
reporters Tuesday afternoon at Marshall Space Flight Center in
Huntsville, Ala.  In reviewing the future of planetary exploration,
Keller said that with Magellan (Venus), Galileo (Jupiter), and
Ulysses (solar interplanetary) launched or about to be, and with
other planetary spacecraft planned or in development, "the U.S. will
have a continuous stream of data to the year 2006."

But those spacecraft will be targeted to orbit specific bodies rather
than playing interplanetary billiards.  "The chances of returning to
Triton, as exciting as it was, are not very good now" he said, and
would probably rely on a high-energy mission with a single gravity
assist at Jupiter.

When asked whether the science community would see on Space Station a
repeat of the "Famous 40," Keller said that, "We will try not to pick
what we can't fly."  The "Famous 40" refers to Shuttle/Spacelab
payloads selected in the late 1970's. Most have not flown on Shuttle
and at least one appears to have been recycled for Space Station.
"We will attempt to honor the commitments that have been made," he
said, and "not make any commitments that cannot be honored in a
particular time."

Among other topics that Keller discussed with reporters:

A joint manned Mars mission with the USSR cannot be decided for at
least another decade since it will take that long to get such an
effort into early planning following Space Station and the Moon.
Meanwhile, joint efforts involving the Mars Observer, ozone mapper on
Meteor 3, and gamma-ray burst detector on the International
Solar-Terrestrial Physics program are providing the "first
engineer-to-engineer discussions" between the two nations.

The Mars Observer still costs less than an all-new mission despite
cost growth that has gone far beyond the "production line" spacecraft
concept. Keller admitted NASA was "overly optimistic" on how low the
price could be held, but said that "the goal of not reinventing the
wheel is one that we should not lose sight of."

----------------- 18 ARTICLES BY TITLE ONLY -------------------------

MAGELLAN WEEKLY STATUS - can890803.txt - 8/3/89
VOYAGER STATUS REPORT - can890804.txt - 8/3/89
VOYAGER STATUS REPORT - can890805.txt - 8/3/89
VOYAGER DISCOVERS 3 ADDITIONAL MOONS AROUND NEPTUNE - can890807.txt - 8/4/89
MSFC CONDUCTS SUCCESSFUL ENGINE TEST - can890808.txt - 8/4/89
    [advanced Space Shuttle main engine]
JSC's COHEN TO LEAD NASA PREPARATION FOR NEW CIVIL SPACE GOALS - can890809.txt
    - 8/4/89
VOYAGER STATUS REPORT - can890810.txt - 8/14/89
MAGELLAN WEEKLY STATUS - can890811.txt - 8/14/89
EUROPE WORKING ON HIPPARCOS BOOSTER PROBLEM - can890812.txt - 8/18/89
VOYAGER STATUS REPORT - can890813.txt - 8/18/89
EUROPE WORKING ON HIPPARCOS BOOSTER PROBLEM - can890814.txt - 8/21/89
GALILEO FINALLY GETTING "OFF THE GROUND" - can890815.txt - 8/21/89
TV SCHEDULE FOR THE VOYAGER NEPTUNE ENCOUNTER - can890816.txt - 8/22/89
LAST PICTURE SHOW DRAWING TO A CLOSE - can890817.txt - 8/24/89
VOYAGER IMAGES SHOW STRIKING DETAILS - can890818.txt - 8/24/89
NASA RESEARCH ANNOUNCEMENT (NRA) 89-OSSA-17 - can890820.txt - 8/29/89
    [Origins of Solar Systems Research Program]
NASA RESEARCH ANNOUNCEMENT(NRA) 89-OSSA-18 - can890822.txt - 8/30/89
    [Long-Term Space Astrophysics Research Program]
NASA RESEARCH ANNOUNCEMENT(NRA) 89-OSSA-19 - can890823.txt - 8/30/89
    [Astrophysics Data Program]

----------------END OF CONDENSED CANOPUS-----------------------------

This posting represents my own condensation of CANOPUS.  For clarity,
I have not shown ellipses (...), even when the condensation is
drastic.  New or significantly rephrased material is in {braces} and
is signed {--SW} when it represents an expression of my own opinion.
The unabridged CANOPUS is available via e-mail from me at any of the
addresses below.

Copyright information:
------------------------------------------------------------------------
CANOPUS is published by the American Institute of Aeronautics and
Astronautics.  Send correspondence about its contents to the executive
editor, William W. L. Taylor ([e-mail]).
Send correspondence about business matters to Mr. John Newbauer,
AIAA, 1633 Broadway, NY, NY 10019.  Although AIAA has copyrighted
CANOPUS and registered its name, you are encouraged to distribute
CANOPUS widely, either electronically or as printout copies.  If you
do, however, please send a brief message to Taylor estimating how
many others receive copies.  CANOPUS is partially supported by the
National Space Science Data Center.
------------------------------------------------------------------------
--
-------------------------------------------------------------------------
Steve Willner            Phone [phone]         Bitnet:   willner@cfa
60 Garden St.            FTS:      830-7123           UUCP:   willner@cfa
Cambridge, MA 02138 USA                 Internet: [e-mail]

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

End of SPACE Digest V10 #186
*******************