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Subject: SPACE Digest V12 #440

SPACE Digest                                     Volume 12 : Issue 440

Today's Topics:
     Re: Lifeless interplanetary travellers - where are they now?
         NASA Headline News for 10/09/90 (Forwarded)
           Re: disposal of N-waste into sun
            Re: deep space comm. protocols
               Any news on lightcraft?

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: 9 Oct 90 16:46:03 GMT
From: sun-barr!cs.utexas.edu!news-server.csri.toronto.edu!utgpu!utzoo![e-mail]  (Henry Spencer)
Subject: Re: Lifeless interplanetary travellers - where are they now?

In article <[e-mail]> [e-mail] (Daniel Fischer) writes:
>Who can tell what has become of all those Upper Stages that were used in the
>past 1.5 years to launch Magellan, Galileo and Ulysses? They were separated
>from the spaceprobes after those had reached their escape velocity, so they
>should be on similar orbits - what steps have been taken to increase their
>distance from the S/C so that accidental collisions or electrical interference
>are excluded? ...

Generally, arrangements are made to give the payload a small velocity
difference from the final stage.  This can be anything from just springs
in the separation mechanism up to a separation burn by a sophisticated
rocket stage.  The IUS is relatively smart and, as I recall, does a
separation burn with the last of its attitude-control fuel.  Relatively
dumb stages, like the final boost motor for Ulysses, just use spring or
pyrotechnic separation and hope for the best. :-)

Actually, even a little bit of separation velocity generally does the
job quite adequately, provided that subsequent velocity changes don't
act to bring the objects together again.  The most notorious case of
this was the amateur-radio satellite (Oscar 10?) that got rear-ended
by the Ariane third stage that had just deployed it -- the stage was
dumping propellants before shutting down, and the dumping gave it
enough forward delta-V to catch up with the satellite.

Space is so big and even small perturbations add up sufficiently over
time that the risk of collision long after separation is slight.  The
stuff ends up in semi-random orbits and blends into all the natural
space junk out there.

>... what has happend to the Galileo-IUS which should have
>been on a rather similar trajectory? Will it also come close to earth again?

I would be surprised.  Gravity-assist maneuvers require hitting a fairly
narrow window at the assist planet.  Galileo's IUS probably ended up
somewhere nearly random after Venus encounter.  Ditto for Magellan's.

>paper in the ESA BULLETIN #63 speaks of 11.4km/s relative to earth, while
>several U.S. media repeatedly talked of 15.2km/s - any explanations welcome].

This might be velocity at infinity vs. velocity at motor burnout.

>And finally: where will Phobos-1 end up? It couldn't orbit-insert at Mars, so
>will it return to earth on its Hohmann-style trajectory? When? ...

My guess would be that it came close enough to Mars to have its perihelion
changed.  Failing that, it would return to Earth's orbit, but the odds are
roughly zero that Earth would be nearby at the time -- Earth's orbit is
half a billion kilometers long.

>... Phobos-2 as well as the
>Viking-Orbiters should be in stable Martian orbits ...

Well, stable except for air drag, which is noticeable even for Mars's thin
atmosphere.  As I recall, Mariner 9 is scheduled to go down circa 1997, and
the Viking orbiters will follow early in the 21st century.  There was
originally hope that serious exploration of the Martian surface would be
underway before these unsterilized spacecraft crashed, but...

>...whether somebody takes care of the whereabouts of the interplanetary
>space debris. The pollution of earth's LEO and GEO is well-known by now, and
>steps to protection are being taken (er, planned (er, talked about)) - but
>who protects interplanetary space?

At present, protection really is not needed.  Tons of human junk are lost
in the gigatons of natural junk already present.  Near-Earth space has a
debris problem because it is small and there is intense activity there.
Ignoring the narrow belt around Clarke orbit for the moment, near-Earth
space essentially ends 1000km up, where the inner Van Allen belt starts
to really make itself felt.  That's about 500 billion [North American
billion, 10^9] cubic km.  Even just cislunar space -- within the average
radius of the Moon's orbit -- is *268 million* billion cubic km, half
a million times larger.  The space between Venus's orbit and Mars's orbit
within, say, five million km of the ecliptic, is very roughly one million
billion billion cubic km.
--
Imagine life with OS/360 the standard  | Henry Spencer at U of Toronto Zoology
operating system.  Now think about X.  |  [e-mail]   utzoo!henry

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

Date: 9 Oct 90 03:47:53 GMT
From: trident.arc.nasa.gov![e-mail]  (Peter E. Yee)
Subject: NASA Headline News for 10/09/90 (Forwarded)


              Headline News
Internal Communications Branch (POC) NASA HQ


Tuesday, October 9, 1990    Audio Service: 202/755-1788


This is NASA Headline News for Tuesday, October 9, 1990

The crew of STS-41 had a very successful weekend starting with
their launch just a few minutes into their window on Saturday, and
continuing with the deployment of the Ulysses solar probe later that
day.  The crew spent yesterday working on cabin experiments and
taking photographs of Tropical Storm Klaus and other Earth features.
Today's agenda has the crew closing up their experiments and
preparing for entry tomorrow morning.  Discovery is set for landing
tomorrow morning at 9:57 am EDT at Edwards Air Force Base.
Weather for Edwards is predicted to be fine for landing.

  * * * * * * * * * * * * * * * * * * * * * * * * * *

At the Kennedy Space Center, Columbia is set to be rolled back to
the Vehicle Assembly Building this morning.  This rollback is based on
Tropical Storm Klaus' trajectory representing a potential threat to
Florida's Space Coast.  Atlantis, still in the VAB, is currently set for roll
out to launch pad 39-A, possibly this Thursday.  Columbia could be
rolled back out to Pad 39-B as early as Friday, with a tanking test
possibly next week.

The investigation into Atlantis' aft compartment beam incident
last week continues, but so far indications are that the damage is very
minor.  A broken purge duct and a small section of a manifold relief line
in the main propulsion system will be replaced.

  * * * * * * * * * * * * * * * * * * * * * * * * * *

Galileo is now about 32 million miles from Earth and closing at a
rate of more than 52,187 miles per hour.  The trajectory correction
maneuver, for fine-tuning the spacecraft's incoming trajectory to Earth,
is scheduled to take place today.  This will change Galileo's velocity by
about 1.1 mph.  Spacecraft health continues to be excellent.

  * * * * * * * * * * * * * * * * * * * * * * * * * *

On Magellan, one of the high power transmitters experienced a
spurious shutdown on Sunday, causing the normal fault protection
procedures to operate.  Thirty-seven minutes of radar mapping data
was lost while the ground system reconfigured.  The shutdown occurred
in the B-side of the traveling wave tube amplifier, a system which has
experienced spurious shutoffs during the earlier cruise mode.  An
investigation of the problem is being conducted.

  * * * * * * * * * * * * * * * * * * * * * * * * * *

Ulysses is on its way to Jupiter at a velocity of more than 34,000
mph.  This is the fastest departure speed of any craft ever to have left
Earth.  On Sunday, Ulysses deployed its radial boom, slowing the craft's
revolution from 6.8 to 4.7 revolutions per minute - as planned.  The next
scheduled event is the pointing of Ulysses' high gain antenna towards
Earth, set to occur later this week.  A trajectory correction maneuver is
also planned for Monday, Oct. 15.


Here's the broadcast schedule for Public Affairs events on NASA Select
TV.  All times are Eastern.  **indicates a live program.

Tuesday, 10/9/90
    2:07 pm    **Earth views and SSBUV operations from Discovery.
    6:00 pm    Replay of STS-41 day 4 activities from JSC.
    6:30 pm    **Change-of-Shift briefing from JSC.

Wednesday, 10/10/90
    2:30 am    **Change of Shift briefing from JSC.
    8:12 am    **Begin landing coverage from DFRF.
    9:57 am    **Expected landing of Discovery at DFRF.
    11:30 am    **Post-landing briefing from DFRF.
    1:15 pm    **Magellan at Venus status briefing from JPL.



All events and times may change without notice.  This report is filed
daily, Monday through Friday, at 12:00 pm, EDT.  It is a service of
Internal Communications Branch at NASA Headquarters.  Contact:
CREDMOND on NASAmail or at 202/453-8425.


NASA Select TV:  Satcom F2R, Transponder 13, C-Band, 72 degrees
West Longitude, Audio 6.8, Frequency 3960 MHz.

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

Date: 10 Oct 90 00:03:48 GMT
From: usenet.ins.cwru.edu!abvax!iccgcc![e-mail]
Subject: Re: disposal of N-waste into sun

In article <[e-mail]>, [e-mail] (Jose Pina Coelho) writes:
> In article <[e-mail]> [e-mail] (Matthew DeLuca) writes:
>>  But, what is wrong with dumping the waste sealed in glass into a subduction
>>  zone on the ocean floor?  The waste would disappear into the mantle of the
>>  earth...what could possibly be wrong with that?
>
> Nothing, just you can't explain a lamp to a troglodite (ecohisterics)
>
>
> You should dump it in a stable (and open) volcano.  The waste would be
> dissolved by several cubic meters of granite.
>
> "But that would make the granite radioactive"
>
> No, because granite is already radioactive (you receive a bigger
> ammount of rad. in a granite house than near a nuclear generator
> (ignoring accidents))
>
> --
> // Pina
>
> - If all men were brothers, would you let one marry your sister ?

Do the arithmetic on dissolving the "high grade" waste in a suitable
solvent and then dispersing it over a few square miles of ocean.  I
think you will find it disappears into the background.  It is high
grade only because the ecohysterics have insisted on concentrating
it into minimum volume.

dan herrick

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

Date: 9 Oct 90 15:26:42 GMT
From: n3dmc!gronk![e-mail]  (John Limpert)
Subject: Re: deep space comm. protocols

[e-mail] (Sean William O Malley) writes:
>I would like to present a deep space communcations
>protocol to my networks class. Does anyone have
>a good reference for such a protocol. I would like
>to cover the error correction and retransmission
>strategy used.

You would get a better answer from someone at JPL
but I will give it a shot.  The telemetry links
use convolutional coding to reduce the bit error
rate.  The ground station uses a sequential decoder
to recover the data.  There is no "protocol" in
the conventional sense.  Engineering measurements
are cyclically digitized and transmitted.  Science
data can be retransmitted by a ground command if
it was logged on the spacecraft's tape recorder.
It's best to think of it as a unidirectional link.
--
John Limpert        [e-mail]    uunet!n3dmc!gronk!johnl

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

Date: 9 Oct 90 20:49:08 GMT
From: sco![e-mail]  (Vulture on the Launch Pad)
Subject: Any news on lightcraft?



A professor at Rensselaer Polytechnic was going to do some preliminary tests
with models for a laser-powered spacecraft propulsion system this summer,
according to a UPI story I read on Clarinet some time back.  Somebody from RPI
later posted to say that they knew some of the people involved in the
lightcraft experiment.

Well?  Does anyone know if the experiments took place and/or what happened?
I'm truly curious.

If anyone wants the original UPI story on lightcraft, I'll forward it.
Apparently some people at NASA admit that the idea is neat (laser + mirror +
spacecraft + supercomputer = cheap spacecraft) but think that implementation
would take decades.  At any rate, NASA has thrown partial funding at
this experiment.
--
________________________________________________________________________________
Jim Jones, [e-mail]              Where logic fails, ego may still prevail.
The Santa Cruz Operation

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

End of SPACE Digest V12 #440
*******************