Space & Astronomy/Space and Astronomy (October 1993).iso/mac/TEXT/SPACEDIG/V16_3/V16NO341.TXT

Text File | 1993-07-13 | 30KB | 737 lines

Date: Sat, 20 Mar 93 05:00:10
From: Space Digest maintainer <[e-mail]>
Reply-To: [e-mail]
Subject: Space Digest V16 #341
To: Space Digest Readers
Precedence: bulk


Space Digest                Sat, 20 Mar 93       Volume 16 : Issue 341

Today's Topics:
                 ALTERNATIVE Comet Rendezvous Mission
                           Aurora spotted ?
                         CD for Pluto Mission
                      Galileo Update - 03/19/93
               Just a little tap (was Re: Galileo HGA)
                         Lunar ice transport
                      plans, and absence thereof
     Predicting gravity wave quantization & Cosmic Noise (2 msgs)
         Road & Track road tests 1996 JPL Rocky IV Microrover
Small Expendable Deployer System Launch Advisory (was Re: Launch Windows
                 SR-71 Maiden Science Flight (3 msgs)
                       Student paper on comets
Threat of mass cancellings was Re: Anonymity is NOT the issue (2 msgs)
    Water Simulations (Was Re: Response to various attacks on SSF)
                  Why use AC at 20kHz for SSF Power?

    Welcome to the Space Digest!!  Please send your messages to
    "[e-mail]", and (un)subscription requests of the form
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    (BITNET), rice::boyle (SPAN/NSInet), utadnx::utspan::rice::boyle
    (THENET), or [e-mail] (Internet).
----------------------------------------------------------------------

Date: Fri, 19 Mar 1993 10:30:21 GMT
From: Dan Tilque <[e-mail]>
Subject: ALTERNATIVE Comet Rendezvous Mission
Newsgroups: talk.politics.space,sci.space,alt.sci.planetary,sci.astro

[e-mail] writes:
>
>                      ALTERNATIVE Comet Rendezvous Mission

Super low-cost (so low it would even satisfy William Proxmire)
Alternative Comet Rendezvous Mission:

    Wait for a comet to rendezvous with us.

And then there's the super low-cost Pluto flyby...

---
Dan Tilque    --     [e-mail]

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

Date: Fri, 19 Mar 93 16:12:09 MET
From: [e-mail]
Subject: Aurora spotted ?

Lawrence Curcio writes (Wed, 17 Mar 1993 15:52:29 -0500):

>How do you know this isn't an ordinary extraterrestrial UFO ?
>
>-Larry
>
>P.S...... :)

Because, up to the present time, extraterrestrial UFOs are extraordinary.
This is what the philosophers call "Occam's razor". I am not very fond
of philosophy, and don't understand much in it (but is there much to
understand ?). However, this Occam's razor principle sounds good. If
I understand correctly, its application can be summarized as follows:
when there are an ordinary and an extraordinary explanation for the
same phenomenon, always choose the ordinary one...

J. Pharabod

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

Date: 19 Mar 93 12:51:00 GMT
From: FRANK NEY <tnc!m0102>
Subject: CD for Pluto Mission
Newsgroups: sci.space

Unless I had a news.hallucination, someone on the group mentioned that
there was a 300g allocation for some sort of commemorative device.
This would fall within the range of a CD-ROM.
--
The Next Challenge - Public Access Unix in Northern Va. - Washington D.C.
703-803-0391 To log in for trial and account info.

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

Date: 19 Mar 1993 16:47 UT
From: Ron Baalke <[e-mail]>
Subject: Galileo Update - 03/19/93
Newsgroups: sci.space,sci.astro,alt.sci.planetary

Forwarded from Neal Ausman, Galileo Mission Director

                                 GALILEO
                      MISSION DIRECTOR STATUS REPORT
                               POST-LAUNCH
                           March 12 -18, 1993
SPACECRAFT

1.  On March 12, as part of the 10 rpm spinup activities, real-time commands
were sent to open the Star Scanner shutter and collect attitude and wobble
data before transitioning to low spin.  Commands were then sent to update the
attitude control subsystem parameters to the low spin values.

     The spacecraft, under stored sequence control, initiated the spin down
at approximately 2123 UTC and completed at 2149 UTC for a duration of 26
minutes.  After the spin down to 2.84 RPM, real-time commands were sent to
enable spin corrects and reduce the spin rate deadband, complete the attitude
control subsystem parameter updates, perform a wobble compensation, and return
to cruise mode (dual-spin at 3.15 RPM).  During the spin down, the minus S1A
thruster temperature exhibited an unusual profile.  Specifically, approximately
six minutes after the spin-down began, the minus S1A thruster increased in
temperature by 25 degrees C (171.8 degrees C) over approximately three minutes
and then stabilized and subsequently decreased slightly prior to soakback.
The temperatures, however, were well within the safe operating range of the
thrusters.

2.  On March 13, the High Gain Antenna (HGA) calibration mini-sequence was
transmitted to the spacecraft without incident. This mini-sequence covered
spacecraft activities on March 14, 1993.

3.  On March 14, the HGA uplink RF (Radio Frequency) test activities were
performed on the spacecraft.  An X-band uplink signal was transmitted to the
spacecraft with the X-band to S-band Down Converter subsystem (XSDC) turned on.
As the spacecraft turned from 5 to 17 degrees off the Earth, uplink S-band
AGC (Automatic Gain Control) data was collected to determine the presence of
any antenna gain pattern.  Analysis of the RF data is in process.

4.  On March 15, a NO-OP command was sent to reset the command loss timer to
240 hours, its planned value during this mission phase.

5.  The AC/DC bus imbalance measurements have not exhibited significant change
(greater than 25 DN) throughout this period.  The AC measurement reads 20 DN
(4.5 volts).  The DC measurement reads 144 DN (16.9 volts).  These measurements
are consistent with the model developed by the AC/DC special anomaly team.

6.  The Spacecraft status as of March 18, 1993, is as follows:

       a)  System Power Margin -  70 watts
       b)  Spin Configuration - Dual-Spin
       c)  Spin Rate/Sensor - 3.15rpm/Star Scanner
       d)  Spacecraft Attitude is approximately 7 degrees
           off-sun (lagging) and 8 degrees off-earth (lagging)
       e)  Downlink telemetry rate/antenna- 40bps(uncoded)/LGA-1
       f)  General Thermal Control - all temperatures within
           acceptable range
       g)  RPM Tank Pressures - all within acceptable range
       h)  Orbiter Science- Instruments powered on are the PWS,
           EUV, UVS, EPD, MAG, HIC, and DDS
       i)  Probe/RRH - powered off, temperatures within
           acceptable range
       j)  CMD Loss Timer Setting - 240 hours
           Time To Initiation - 162 hours


GDS (Ground Data Systems):

1.  The March System Engineers Monthly Report (SEMR) review was conducted
Thursday, March 11.  A review of current Project and Institutional (DSN and
MOSO) system status was conducted.  Near-term  delivery schedules, past months
accomplishments and potential problem areas were discussed.  No significant
schedule changes or significant problems were reported.


TRAJECTORY

     As of noon Thursday, March 18, 1993, the Galileo Spacecraft trajectory
status was as follows:

    Distance from Earth         94,267,000 km (0.63 AU)
    Distance from Sun           239,247,000 km (1.60 AU)
    Heliocentric Speed          103,500 km per hour
    Distance from Jupiter       594,763,900 km
    Round Trip Light Time       10 minutes, 32 seconds


SPECIAL TOPIC

1.  As of March 18, 1993, a total of 67634 real-time commands have been
transmitted to Galileo since Launch.  Of these, 62528  were initiated in the
sequence design process and 5106 initiated in the real-time command process.
In the past week, 54 real time commands were transmitted: 54 were initiated
in the sequence design process and none initiated in the real time command
process.  Major command activities included commands to open the star scanner,
collect attitude and wobble data, update attitude control subsystem parameters,
enable spin corrects and reduce the spin rate deadband, perform a wobble
compensation, uplink the HGA RF test mini-sequence and reset the command loss
timer.
     ___    _____     ___
    /_ /|  /____/ \  /_ /|     Ron Baalke         | [e-mail]
    | | | |  __ \ /| | | |     Jet Propulsion Lab |
 ___| | | | |__) |/  | | |__   M/S 525-3684 Telos | Don't ever take a fence
/___| | | |  ___/    | |/__ /| Pasadena, CA 91109 | down until you know the
|_____|/  |_|/       |_____|/                     | reason it was put up.

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

Date: Fri, 19 Mar 1993 16:11:32 GMT
From: Nick Haines <[e-mail]>
Subject: Just a little tap (was Re: Galileo HGA)
Newsgroups: sci.space

In article <[e-mail]> [e-mail] (Pat) writes:

   Besides,  if the HGA opened, and the probes went off course, it would
   be a wash.  the orbiter would get most of the imaging data, but the probe
   mission may get lost.   kinda a trade off.   Lousy deal, but no worse then
   the deal we got now.

`the deal we got now' is a fine one. We're going to get 70% of the
mission objectives. Most of the real science on Galileo will go ahead.
Most of what we'll miss will be pretty pictures (which we'll still get
enough of to keep the TV people happy).

I fail to understand why people are so _desperate_ to get the HGA
open. Certainly it's insane to suggest jeopardizing the mission merely
in order to get a few more pictures (e.g.  the recent suggestion of
an aerobrake manouevre at Jupiter to stress the HGA).

Nick Haines [e-mail]

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

Date: 19 Mar 93 16:08:48 GMT
From: Russ Brown <[e-mail]>
Subject: Lunar ice transport
Newsgroups: sci.space

In article <[e-mail]> [e-mail] (Henry Spencer) writes:
>In article <[e-mail]> [e-mail] (Ross  Borden) writes:
>>be buried in the regolith (an excellent insulator).  Does anyone know
>>what the mean temperature of regolith is at, say, 2 meters ?
>
>We only have a few data points, but they're all within a degree or two
>of 255K.  The variation is from site to site -- the temperature at any
>particular site is absolutely constant at that depth.

Usenet works!

Keihm and Langseth reported (1973 Apollo 17 data) a mean temperature of
256K at 1.3 metres; little variation would be expected at that depth in
the regolith.

At the surface, the temperature varied from 102K to 384K during the
lunar day.

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

Date: 19 Mar 1993 12:03:23 -0500
From: Pat <[e-mail]>
Subject: plans, and absence thereof
Newsgroups: sci.space,alt.sci.planetary

In article <[e-mail]| [e-mail] (Nick Szabo) writes:
|[e-mail] (Pat) writes:
|
|>JPL  A) Has their plate pretty full doing existing missions.
|
|Quite the opposite, they are laying people off and rapidly
|revamping their strategies in search of new missions.  It's
|a time of flux at JPL, a time for it to incorporate new
|strategies and visions to take advantage of the new technology
|and knowledge we have going into the 21st century.
|

If JPL had more money, they'd be working the missions that are
already on their punchlist.   CRAF.  Magellan cycle 5,  Ongoing
voyager, mariner data analysis.  MO, Lunar Observer.  I know
I've banged JPL hard for spending too much money to achieve
goals,  but I think that's an administrative problem.
They only have n scientists and designers,  and they already
have beaucoup things to do.  NEAR is approved,  MESUR looks go.
I really doubt they can divide resources much farther.

|>     B) is oriented to certain mission types, and prospecting
|>    is a little out of their balliwick..
|
|JPL, Caltech, and universties that work closely with it such
|as U. of Arizona, are chuck full of planetary scientist/geologists.
|There are dozens of quite talented planetary geologists who work
|in the oil and mining industries.  JPL and the planetary science
[szabo deleted on Prospecting, plasma science...]

Wouldn't the lunar and Planetary science institute at JSC be a better
site for this stuff.  They already have all the Data on the planets.
And texans know all about drilling for oil.   Besides they have been
looking for a mission since apollo ended.

And witht he senate seat for Texas up for grabs,  Clinton needs political help
there.



|
|>get basic operating costs in space down by 2 orders of magnitude.
|>Then the market will do the rest.
|
|But right now planetary science is operating without any feedback
|from markets, real or potential.  That's why we haven't flown
|a lunar orbiter -- there's not much basic science for it to do,
|but it is one of the top-priority projects from a future-market
|prospecting point of view.  Planetary science and the associated
|native materials processing plays a central role in dropping costs
|by orders of magnitude, leapfrogging the very slow trend in
|launch cost reduction since the 1960's by opening up sources of
|industrial supply off earth.


Nick,  no matter abou;Processing basic industrial stocks in orbit,
the Hardware has to fly up,  and that still costs way to much.
All the ideas you talk about have their place, in time,  but until
we can get Boxes up there cheap,  get techs up there cheap
and reliably,  it doesn't matter if king midas's moon is just on the
dark side of tycho.

pat

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

Date: 19 Mar 93 11:42:37 GMT
From: [e-mail]
Subject: Predicting gravity wave quantization & Cosmic Noise
Newsgroups: sci.space,sci.astro,sci.physics,alt.sci.planetary

In article <[e-mail]>, [e-mail]. (Thomas E. Smith) writes:
> same time (I forget if gravity travels the speed of light, or is instantly
> propagated)

Instantly propagated????? - Are you nuts?  :-)
Then we wouldn't get waves and that would screw up the relativity theory!

Volker

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

Date: Fri, 19 Mar 93 13:07:44 GMT
From: Greg Stewart-Nicholls <[e-mail]>
Subject: Predicting gravity wave quantization & Cosmic Noise
Newsgroups: sci.space,sci.astro,sci.physics,alt.sci.planetary

In <[e-mail]> [e-mail] writes:
>In article <[e-mail]>, [e-mail]. (Thomas E. Smith) writes:
>> same time (I forget if gravity travels the speed of light, or is instantly
>> propagated)
>
>Instantly propagated????? - Are you nuts?  :-)
>Then we wouldn't get waves and that would screw up the relativity theory!
>
>Volker
>
 <dumb question on> Wouldn't a gravity wave distort space, and affect
the instrumentation to exactly the same degree as the object being
measured ???
 -----------------------------------------------------------------
               ** Of course I don't speak for IBM **
Greg Nicholls ... [e-mail] (business) or
                  [e-mail] (private)

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

Date: 18 Mar 93 22:35:54 GMT
From: Ken Kiesow <[e-mail]>
Subject: Road & Track road tests 1996 JPL Rocky IV Microrover
Newsgroups: sci.space

Does anyone remember the comparison betw. the Concorde
and the QE2?  That one was quite humorous as well...

Ken Kiesow
[e-mail]

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

Date: Fri, 19 Mar 1993 16:45:09 GMT
From: Nick Haines <[e-mail]>
Subject: Small Expendable Deployer System Launch Advisory (was Re: Launch Windows
Newsgroups: sci.space

So what happened?

Nick Haines [e-mail]

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

Date: 19 Mar 93 09:20:21 GMT
From: Jostein Lodve Trones <[e-mail]>
Subject: SR-71 Maiden Science Flight
Newsgroups: sci.space

Just a small simple question (sorry if I missed this earlier..)

When was the first SR-71 flight? (not first science flight, but *first*)

Thanks!
Cheers,
    Jostein

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

Date: Fri, 19 Mar 93 10:26:02 GMT
From: Dean Adams <[e-mail]>
Subject: SR-71 Maiden Science Flight
Newsgroups: sci.space

In article <[e-mail]> [e-mail] (Jostein Lodve Trones) writes:
>
>Just a small simple question (sorry if I missed this earlier..)
>
>When was the first SR-71 flight? (not first science flight, but *first*)

You mean the first flight EVER?

The very first would have been the A-12, on April 26, 1962.

The first actual SR-71 few on December 22, 1964...

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

Date: Thu, 18 Mar 1993 17:56:55 GMT
From: Rob Healey <[e-mail]>
Subject: SR-71 Maiden Science Flight
Newsgroups: sci.space

In article <[e-mail]>, [e-mail] (John S. Neff) writes:
|> Please explain the advantage of the SR-71 over a ballon for UV
|> spectrophotometry. The maximum altitude of the SR-71 listed in a previous
|> post was about the same, or a little lower, than the normal altitude of
|> a ballon flight.

    The SR-71 can take measurements across a wider area at that
    height, it can also take measurments in day, night and terminator
    between day/night all in 1 flight, i.e. within a short period of
    time. This wide sample space may provide useful information beyond
    what a balloon's sample space would be.

        -Rob

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

Date: 19 Mar 93 13:08:32 GMT
From: Joe Cain <[e-mail]>
Subject: Student paper on comets
Newsgroups: sci.astro,alt.sci.planetary,sci.space

A non-science student is doing a project report on comets for her
planetary geology class. I am supplying some references but wanted to
ask if anyone has handy the latest proposal for a replacement for
CRAF. Also, what is the latest on the Kuiper belt idea?

(Tanks to the net also for the input from several to the student
writing up the "hazards from space" report. The new material will keep
him busy all next week.)

Joseph Cain        [e-mail]
[e-mail]        scri::cain
[phone]        FAX [phone] or -0098

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

Date: Mon, 15 Mar 1993 09:14:21 GMT
From: Darin Wayrynen <[e-mail]>
Subject: Threat of mass cancellings was Re: Anonymity is NOT the issue
Newsgroups: news.admin.policy,news.admin,comp.org.eff.talk,sci.space,alt.privacy

In article <[e-mail]> [e-mail] (Joe Sharkey) writes:
>In article <keng.731967549@tosgcla> [e-mail] (Ken Garrido) writes:
>>
>>Now I'm not a news wizard, but can't you generate a file which *automatically*
>>screens the messages which are presented to you ?
>...
>>Why don't we _just_ _not_ _listen_ to anonymous posts ?
>
>Maybe because some of pay real money out of our own pay check( (sic) for news?
>
>Much better if this stuff didn't exist: who pay good money for something that's
>just going in the bit-bucket?
>
>>Ken Garrido     [e-mail]     Martin Marietta Aerospace
>                                   See!   ---->^^^^^^^^^^^^^^^^^^^^^^^^^
>
>joe.

Here's something to think about Joe.  We all hide behind an electronic
wall here.  You're name might not even be Joe Sharkey.  Mine might not
be Darin Wayrynen.  For you to say that someone's post is worthless
because they hide behind a name that states that they are remaining
anonymous is sort of silly.

Do you think that because your name isn't synonymous with anonymous
that means it carries more weight?

>--
>Joe Sharkey      [e-mail]      ...!uunet!ibmpcug!jshark!joe
>150 Hatfield Rd, St Albans, Herts AL1 4JA, UK        Got a real domain name
>([phone]           Mail/News Feeds (v32/v32bis): [e-mail]

--
==========================================================================
Darin Wayrynen                        UUCP:     uunet!uupsi4!infogrf!darin
Paragon Consulting Group              INTERNET: [e-mail]
                                      PHONE:    [phone]

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

Date: Mon, 15 Mar 1993 10:06:25 GMT
From: Darin Wayrynen <[e-mail]>
Subject: Threat of mass cancellings was Re: Anonymity is NOT the issue
Newsgroups: news.admin,comp.org.eff.talk,sci.space,alt.privacy,news.admin.policy

In article <[e-mail]> [e-mail] writes:
>"William C. Hulley" <[e-mail]> writes:
>
>>
>> we can assume that three things will happen if rick enacts his
>> delightfully sensitive censorship scheme:
>>
>>     - his site will be cut off from the rest of the net,
>>
>>     - another anonymous site with a different naming scheme will be started
>>       within hours,
>>
>>     - someone will try to post anonymously and when that post is
>>       "moderatedly moderated" he or she will contact the EFF and the ACLU
>>       and begin, probably through the courts, an action to protect our
>>       first amendment rights.
>>
>> gee rick, i dunno, this ARMM thingy doesn't sound like such a good
>> idea, maybe you should think about it just a wee bit more before you
>> implement it.
>
>
>I think that you are right on this... first, if I posted anon and it suddenly
>disappeared then I'd sure start wondering what happened. Let's think now,
>the only way rick can stop a post if it his site is the first to receive
>it. Otherwise, the anon will get into the group and passed on endlessly.
>The only sites that will have this major kludge is his and any he feeds.
>

If I'm not mistaken, the cancel messages could easily past his system.
If he is sent Usenet mail from his feed before his feed feeds others,
and he cancels a message (and sends that cancel back to his feed), and
his feed honours that cancel, then the message he cancel will be
eliminated down wind from his feed.  If his feed further moves that
cancel along back to its feed, then it's possible it could cancel
another branch, and so on and so on.

What would happen is that the cancel would go everywhere and cancel
the message everywhere where local News Admins did not take pro-active
precautions against his cancels.

Sure the original anonymous message might be canceled hours/days after
it reached a site, but the fact remains, it would still be canceled...

By the way, I totally disagree with his tirade.

[deletions]

>-----------------------------------------------------------------------------
> Buy & Sell American When Possible!  <->  All Standard Disclaimers Do Apply!
> [e-mail]  (George W. Pogue  (Bill ))
>-----------------------------------------------------------------------------


--
==========================================================================
Darin Wayrynen                        UUCP:     uunet!uupsi4!infogrf!darin
Paragon Consulting Group              INTERNET: [e-mail]
                                      PHONE:    [phone]

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

Date: Fri, 19 Mar 1993 16:37:10 GMT
From: Frank Crary <[e-mail]>
Subject: Water Simulations (Was Re: Response to various attacks on SSF)
Newsgroups: sci.space

In article <[e-mail]> [e-mail] (Henry Spencer) writes:
>Nobody is saying that the water tanks are valueless.  The astronauts
>themselves say that the tanks are the best ground-based simulation of
>free fall.  The point is, the fidelity of most any simulation is limited,
>and *we don't know where the limits are*.  The Intelsat problem was a
>nasty surprise.  There are probably more such surprises lurking.

Just to toss in the Soviet Union's experience on Salyut 6 and 7 and
on Mir: On a few occasions, the Soviets have been unable to train
an EVA team on the ground, using water tanks (Either because schedueling
problems forced a different, untrained crew to make the EVA, or
because some immediate problem required an unplanned repair EVA.)
Untrained crews usually take about 50% longer than a trained one
to do the same job, but both take longer than the training/simulation
would predicet, becuase of unexpected problems, that water tanks
don't accurately simulate.

                                                    Frank Crary
                                                    CU Boulder

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

Date: 19 Mar 93 12:56:30 GMT
From: Thomas Clarke <[e-mail]>
Subject: Why use AC at 20kHz for SSF Power?
Newsgroups: sci.space

In article <[e-mail]>
[e-mail] (David B. Mckissock) writes:
Interesting discussion of the advantages of AC over DC and
then the advantages of higher frequency AC over lower frequency
AC deleted.
> This eliminates a
> major source of losses in modern power processing equipment,
> and typically cuts inverter losses in half, from approximately
> 10% to approximately 5%. Since a percent is around 500 W (on
> the PMC station), that means a savings on the PMC station of
> about $25 million. If we also add total life cycle costs
> for the entire mission, that savings can grow to between
> $100 million and $150 million, depending on how conservative
> your analysis rules are.

However, since 20 kHz gear is not commercial off-the-shelf, whereas
aircraft-qualified 400 Hz gear is, how much extra would it cost
to develop this totally new technology?  Would the $25 million
savings in PMC (smaller solar array ?) offset the development
cost of this entirely new technology?  Clearly, life-cycle savings
don't count:  either Congress or NASA bureaucracy (depending on which
side of the debate you are) always goes for the lowest up-front cost :-(
I suspect that $25 million has been spent on 20 kHz feasiblity already.

--
Thomas Clarke
Institute for Simulation and Training, University of Central FL
12424 Research Parkway, Suite 300, Orlando, FL 32826
[phone], FAX: [phone], [e-mail]

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

Date: Fri, 19 Mar 93 15:45:53 EST
From: [e-mail]

Paris, 19 Mars 1993
Report du lancement de Spacelab D-2

Le lancement de la navette Columbia, qui devait emporter la
deuxieme mission allemande du Spacelab (D-2) ce dimanche
21 mars, a ete reporte de 24 heures pour des raisons d'ordre
meteorologique.

Delay of the launch of Spacelab D-2

The launch of the Shuttle Columbia scheduled to fly the
second german Spacelab mission (D-2) this next Sunday 21
March, has been delayed for 24 hours due to meteorological
reasons.



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

Date: Fri, 19 Mar 93 16:10:41 EST
From: [e-mail]

Press Release Nr.13-93
Paris, 19 March 1993

Searching for gravity waves in space

Three interplanetary spacecraft, ESA's Ulysses and NASA's
Mars Observer and Galileo, now quietly heading towards
separate destinations (the poles of the Sun, Mars and Jupiter
respectively), may soon prove the existence of waves in the
universe's gravitational field by bobbing on ripples in space
like corks bobbing on ripples in a pond.

Such gravity waves have never been directly detected,
although their existence was predicted in Einstein's theory of
relativity and there is indirect evidence that they exists. The
waves are believed to be produced by supernova explosions,
collapsing black holes and other events of this kind. Past
searches with ground-based equipment and single spacecraft
have failed to discover them.

This joint ESA/NASA experiment will run from the 21st of
March to April the 11th and for the first time three spacecraft
will make observations simultaneously, greatly increasing the
reliability of any detection. Astrophysicists are hoping to make
this major discovery by spending the next few weeks
"listening" for passing gravitational waves with the three
"borrowed" space probes at the same time in the most
sensitive detection system yet assembled to search for very
low frequency gravitational waves.

"For Ulysses it will be the second chance to search for these
rare events. Last March, Ulysses "listened" for a period of
about four weeks." said Dr. Richard G. Marsden, Deputy
Ulysses Project Scientist at ESA's  Research and Technology
Centre, ESTEC, in Noordwijk, the Netherlands. "Although no
gravitational waves were found on that occasion, the
experiment set new upper limits to their intensity, thereby
excluding a number of possible sources." said Prof. Bruno
Bertotti, Principal Investigator of the Ulysses Gravitational
Wave Experiment at the University of Pavia, Italy.

ESA's Ulysses spaceprobe was launched by Space Shuttle
Discovery on October 6, 1990 to become the first probe ever
to explore and circumnavigate the poles of the Sun. In
February 1992 the spacecraft approached Jupiter and made use



of the gravitational pull of the giant planet to "swing" itself
out of the ecliptic plane, the imaginary "disc" in which all the
planets of the Solar System orbit around the Sun.

"Ulysses is now 4,9 astronomical units -735 million km- from
the Sun and 20 degrees South of the ecliptic plane on its way
to fly over the South polar region of the Sun between May
and September next year" said Dr. Peter Wenzel, ESA's
Ulysses Project Manager.

A year later, in September 1995, Ulysses will have passed
over the North pole of the Sun completing its almost 5 year
long journey towards the unknown.




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

End of Space Digest Volume 16 : Issue 341
------------------------------