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Subject: SPACE Digest V13 #304

SPACE Digest                                     Volume 13 : Issue 304

Today's Topics:
               * SpaceNews  25-Mar-91 *
                Re: "Follies"
            Re: Japan Moon Probes article
             Re: Galileo asteroid imaging
             Where can I find space GIFs?
              Galileo Update - 03/20/91
            Magellan Update #2 - 03/20/91

Administrivia:

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

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

Date: 23 Mar 91 02:03:31 GMT
From: ka2qhd![e-mail]  (John Magliacane)
Subject: * SpaceNews  25-Mar-91 *


SB SPACE @ AMSAT < KD2BD $SPC0325
* SpaceNews  25-Mar-91 *

Bulletin ID: $SPC0325


                              =========
                              SpaceNews
                              =========

                         MONDAY MARCH 25, 1991

SpaceNews originates at KD2BD in Wall Township, New Jersey, USA.  It
is published every week and is made available for unlimited distribution.


* U2MIR NEWS *
==============
U2MIR Activity Patterns   by John Shalamskas, KJ9U  3/17/91

Evidently, the best times to work the cosmonauts "live" are weekends UTC,
with some leeway for Fridays and Mondays.  Currently, their work schedule
of 08:00 to 23:00 Moscow time means that they are asleep from 23:00 to
08:00 Moscow time.  Watch for passes during their wakeful hours if you
wish to have a "live" conversation.  It's quite an experience!

UTC: "Prime Time" hours are from 05:00 to 20:00 Friday - Monday

For the record, his name is pronounced "Moo'sah", and he really does
have some trouble with the English language.


* STS-37 NEWS *
===============
A Flight Readiness Review for STS-37 is scheduled for March 26 and 27.
Shuttle Amateur Radio EXperiment (SAREX) schedules have already been
made with various schools around the country.  On 05-Apr-91, several
"bridges" have been scheduled so astronauts can communicate directly
with school children using Amateur Radio.  Contacts will be made at
15:11, 18:29 and 20:20 UTC using both voice and slow-scan television
(SSTV) on this date.  Audio re-transmissions of these bridges should
be available on WA3NAN, the Amateur Radio club station at the Goddard
Space Flight Center in Greenbelt, Maryland.

[Info via N9JEL]


* PACSAT NEWS *
===============
After spending two weeks studying memory dumps, NK6K and G0/K8KA have
determined the cause of the on-board computer crash which occurred on
AO-16 March 2.  NK6K traced the crash back to an inefficient way in
which a "homebrew" PACSAT user program requested information about new
files stored on the BBS.  Because of the slow way the search for new
files was being performed and the fact that at the time of the crash there
were over 560 files stored, the file server took a lot longer to search
than normal.  After sixty seconds, a critical software timer timed out,
and as NK6K put it, "the dominoes started falling."

Now that this problem has been identified, G0/K8KA has made a change in
the PACSAT file server software so that this problem won't re-occur.
Also, new implementation notes will be published so that all writers of
PACSAT ground station user software will be aware of the change in the
PACSAT Protocol.

As of 03:00 on March 15, 1991, the BBS on AO-16 was back in operation.
Likewise, the BBS on LUSAT-OSCAR-19 (LO-19) was on-line, according to
LU7XAC.  It is believed that the LO-19 on-board computer crash was due
to the same problem, manifest in a slightly different way.  NK6K points
out that PACSAT BBS software is much more robust with each new version,
and the time between crashes is increasing.

[Info via ANS]


* INTERSTELLAR QRM *
====================
145.825 MHz has become a popular frequency for VHF radio links with OSCAR
satellites.  At the present time, 145.825 MHz is used as a downlink for
both OSCAR-11 (UoSAT-2) and OSCAR-17 (DOVE-1).  RS-14/OSCAR-21 is a close
neighbor, using 145.822 MHz for a CW telemetry beacon.  At the same time,
RS10 and RS11 use this frequency (+/- 5 KHz) for uplinks to their auto-
transponders, or "robots".

The popularity of 145.825 MHz has created some real problems!  On frequent
occasions, OSCARs 11, 17 and 21 can all be heard at once, causing severe
interference between satellites and making it impossible to copy ANY
satellite when all three come into range at once.  There have also been
occasions when RS10 or RS11's "robot" uplinks have been interfered with by
constant carrier (FM) emissions from OSCAR 11 and/or 17.  Since many OSCAR
satellites are placed in sun-synchronous orbits, they often come into range
of a given satellite groundstation at about the same time every day, and if
they all use the same beacon frequency, the severe interference problem
results.

145.825 MHz is simply getting too crowded for practical use.  Even the
short-lived BADR-1 spacecraft used this frequency as an outlet for its
telemetry beacon.  Perhaps we should look toward using the 144.300 to
144.500 MHz OSCAR subband in future amateur spacecraft.

Something to think about.... de KD2BD


* TNX QSL! *
============
A special thanks to all those who sent QSLs to SpaceNews:

KB2HMK  : Michel Zadoroznyj, Garfield, New Jersey, USA
N3IKS   : John Ford Gibson III, Philadelphia, Pennsylvania, USA
N6YGD   : Donald Bowtell, Byron, California, USA
WB9OKM  : Leland Ronzheimer, Waukegan, Illinois, USA
WT0N    : B.J. Arts, Plymouth, Minnesota, USA

...and e-mail messages:

KB2FID, N2AAM, VK2BBD, WA2N, TI3DJT, KC4UZA, SM6JNS, N9JEL


* FEEDBACK WELCOMED *
=====================
Feedback regarding SpaceNews reports may be directed to the editor using
any one of the following paths:

INTERNET : [e-mail]
PACKET   : KD2BD @ NN2Z.NJ.USA.NA
UUCP     : ...rutgers!ka2qhd!kd2bd

MAIL     : John A. Magliacane, KD2BD
           Electronics Technology Department
           Advanced Technology Center
           Brookdale Community College
           765 Newman Springs Road
           Lincroft, New Jersey  07738
           U.S.A.

/EX
--
John A. Magliacane                 FAX  : [phone]
Electronics Technology Department  AMPR : KD2BD @ NN2Z.NJ.USA.NA
Brookdale Community College        UUCP : ...!rutgers!ka2qhd!kd2bd
Lincroft, NJ  07738  USA           VOICE: [phone] ext 607

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

Date: Thu, 21 Mar 91 19:43:17 EST
From: John Roberts <[e-mail]>
Disclaimer: Opinions expressed are those of the sender
    and do not reflect NIST policy or agreement.
Subject: Re: "Follies"


>From: [e-mail] (Perry G Ramsey)
>Subject: Re: "Follies"
>Summary: Apples to Granite comparison

>> A comparison with past efforts is interesting. According to (I think) G.
>> Harry Stein, both the Plymouth Rock and Salt Lake City colonies where started
>> with 50 middle to upper middle class famlies selling everything they owned
>> to pay for the voyage.

>The obvious differences are that both Massachusetts and northern Utah
>support human life quite readily.  Food, water, building materials,
>etc. are all readily and cheaply available.  In sharp contrast to the
>moon.

Though as far as the Plymouth colonists were concerned, they might as well have
been on the surface of the moon. And if a group with the intellect and
preparedness of the Plymouth colonists ever land on the moon, I expect
they'll all rush out without pressure suits and be dead in a few minutes.

Before we really get going on this latest round of historical analogies
(much like the one last year and the one the year before that), might I
point out that trying to make historical comparisons between two situations
in which the individual parameters are almost all different is very unlikely
to produce any useful conclusions? :-)

>Of course, the Salt Lake City and Plymouth colonists sold everything
>and endured great hardship to GET AWAY from the government, not to
>go live in a government owned hole in the ground.

While there may have been some pressure on Puritans in England, I believe
the main reason they wanted to move to America is that it enabled them to
set up their own tyrannical (theocratic) local government. It wasn't so
much liberty for Puritans they needed as it was the ability to persecute
non-Puritans.

I suspect the first space colonists will be united more by their interest
in space than by political agendas.

>Perry G. Ramsey           Department of Earth and Atmospheric Sciences
>[e-mail]    Purdue University, W. Lafayette, IN USA
>[e-mail]   ***  IMAGINE YOUR LOGO HERE  ******
            John Roberts
            [e-mail]

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

Date: 22 Mar 91 15:04:40 GMT
From: phoenix![e-mail]  (Edwin L Turner)
Subject: Re: Japan Moon Probes article

In article <[e-mail]> [e-mail] (Ron Baalke) writes:
>The Times says the $100 million mission would make the
>Japanese the third group to land a probe on the moon, after the
>U.S. and the Soviet Union.  The story says the probes will be
>ready in Spring, 1996.

And you can safely bet that they will be, too.

Ed Turner            "The truth is never taken
phoenix!elturner         From another.
                 One carries it always
                 By oneself."
or
[e-mail]                     - Tetto Giko, 1369

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

Date: 23 Mar 91 02:29:16 GMT
From: usc!samsung!munnari.oz.au!uhccux![e-mail]  (David Tholen)
Subject: Re: Galileo asteroid imaging

>> The lightcurve variations suggest a complex shape, and the images
>> may be quite dramatic.
>
> Complex?  I'd prefer the term "asymmetric".  More egg-shaped than the usual
> tri-axial ellipsoids used for modeling lightcurves.  I'm confident that the
> images we do get will be dramatic, but I'm biased.  We will probably also
> get a lot of blank frames, because the asteroid's location won't be known
> that well, but we're working on it.

Just to briefly followup on my earlier response, the 1988 lightcurve published
by DiMartino could be considered complex.  However, they did not mention in
their paper that the lightcurve was obtained within a few degrees of the
galactic center.  I am confident that some of the fine-scale "complex"
structure seen in their lightcurve is, in fact, due to field star
contamination.  More recent lightcurves are substanitally smoother in
appearance, though asymmetric.

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

Date: 20 Mar 91 18:26:04 GMT
From: mixcom![e-mail]  (Robotic Systems)
Subject: Where can I find space GIFs?

Can someone please tell me where I might find GIFs of planets (ie. NASA
pictures) and who might send them to me via e-mail? I do not have ftp.

Thanks.

Clint Laskowski
Robotic Systems

[e-mail]

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

Date: 20 Mar 91 21:36:53 GMT
From: swrinde!elroy.jpl.nasa.gov!jato!mars.jpl.nasa.gov![e-mail]  (Ron Baalke)
Subject: Galileo Update - 03/20/91


                        GALILEO STATUS REPORT
                           March 20, 1991

     Today, the Galileo spacecraft is about 36 million miles from Earth and
110 million miles from the Sun, traveling at a heliocentric speed of
68,700 miles per hour.  Round-trip communication time is 6 minutes, 24 seconds.

     Galileo is executing a Trajectory Correction Maneuver to help shape the
flight path for its encounter of the asteroid Gaspra on October 29.  In the
maneuver Galileo will fire its small thrusters on and off during a period
beginning at about 10 AM Pacific Standard Time (PST) and concluding at about
1:30 PM PST.  The firings will result in a velocity change of about 5 miles
per hour.

     For the rest of the week, the spacecraft will continue with routine
housekeeping activities and readouts of data from science instruments.
      ___    _____     ___
     /_ /|  /____/ \  /_ /|      Ron Baalke         | [e-mail]
     | | | |  __ \ /| | | |      Jet Propulsion Lab |
  ___| | | | |__) |/  | | |___   M/S 301-355        | Change is constant.
 /___| | | |  ___/    | |/__ /|  Pasadena, CA 91109 |
 |_____|/  |_|/       |_____|/                      |

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

Date: 20 Mar 91 21:40:48 GMT
From: swrinde!elroy.jpl.nasa.gov!jato!mars.jpl.nasa.gov![e-mail]  (Ron Baalke)
Subject: Magellan Update #2 - 03/20/91


                         MAGELLAN STATUS REPORT
                       DMS-A Tape Recorder Review
                            March 20, 1991

     JPL, Martin Marietta, and Odetics conducted a review of the progress in
analyzing the DMS-A (Data Management Subsystem-A) tape recorder problem on
Monday, March 11 at JPL.  Assessment of the data played back from Test #3 on
the spacecraft DMS-A tape recorder has shown a number of areas which are
confusing.  Test #3 involved recording known test data patterns on each of
the four tape recorder tracks at both the high and low record rates in order
to investigate the "pattern sensitivity" of the problem.

     The tape recorder motor current seen in the real-time spacecraft
telemetry appeared normal, rather than showing the noise spikes associated
with the DMS-A problem.  This noise is caused by the motor control circuitry
trying to track a noisy clock signal recovered from the data on tape.  Despite
the apparently "good" motor current, the replayed data itself appeared to be
seriously degraded.  Most strikingly, no data at all appeared to be recovered
from track 2, the first of the DMS-A tracks to begin to go bad.  This calls
into question the earlier Test #1 result, which had used the failure to find
data on an "erased" area of Track 2 to confirm that the erase mechanism is
working satisfactorily.

     A second replay of the same recorded test data (from only Track 1) was
performed on Friday, March 8, to attempt to resolve this confusion.  Early
assessments of the second playback show substantial differences from the first
playback.  In fact, the data appeared to be quite good at first glance.

     Martin and JPL are in the process of re-examining both data playbacks to
resolve these assessments.  The ground tests at Odetics have shown that
several of the candidate failure mechanisms did not cause the same pattern of
data replay problems which have been characteristic of DMS-A.  In fact, the
ground tests have shown the units tested to be highly robust against the faults
induced, including failure of the fine erase head winding, partial failure of
the coarse erase head winding, and partial magnetization of the record head.

     The most promising candidate failure mechanism to emerge from the ground
tests is a possible "stuttering" of the clock provided to the tape recorder
from the Command Data Subsystem (CDS) computer.  By inserting "extra" clock
pulses, such a clock problem could cause the data encoding/decoding mechanism
to fail in a pattern similar to many of the observed data errors.  Such a clock
problem could be caused by ringing or noise affecting the clock transfer over a
short length of cable from the CDS to DMS-A.  The transfer cable lengths to
DMS-A and DMS-B are equal, and no such problem has been seen on DMS-B.

     The immediate actions after the review were to concentrate on reaching a
sound assessment of the real results from Test #3, so as to separate true
spacecraft problems from ground data handling anomalies.  In addition, the
planning for the delayed Test #2 on the spacecraft, using an area of tape which
has not been used since cruise (well before the DMS-A fault appeared) is
continuing.
      ___    _____     ___
     /_ /|  /____/ \  /_ /|      Ron Baalke         | [e-mail]
     | | | |  __ \ /| | | |      Jet Propulsion Lab |
  ___| | | | |__) |/  | | |___   M/S 301-355        | Change is constant.
 /___| | | |  ___/    | |/__ /|  Pasadena, CA 91109 |
 |_____|/  |_|/       |_____|/                      |

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

End of SPACE Digest V13 #304
*******************