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[jamsat-news:623] * SpaceNews 25-Aug-97 *

* SpaceNews 25-Aug-97 *

BID: $SPC0825


			  MONDAY AUGUST 25, 1997

SpaceNews originates at KD2BD in Wall Township, New Jersey, USA.  It
is published every week and is made available for non-commercial use.

Stacy Mills, W4SM, reports that AMSAT-OSCAR-10's downlink signals continue
to be strong.  During portions of the pass when the squint angle is
considerably greater than 90 degrees, masking of the omni antenna by the
spacecraft's three lobes causes the deep QSB noticed.  Given Stacy's
previously "guesstimated" ALON/ALAT which has now precessed to approximately
ALON=154, ALAT=+43, AO-10 should have a solar angle of about 6 degrees on
21-Aug-97, giving 99% or grater illumination.  After 24-Aug-97, the solar
angle will begin to move toward the antenna end of the spacecraft.  By
06-Nov-97, illumination should be down to about 35%, and signals should
be considerably diminished.  The sun will directly shine on the antenna
end of AO-10 (illumination = 0) on about 29-Nov-97, and it should be in
the middle of its next "sleep" period at that time.

BIG DISCLAIMER: All the above assumes that the attitude is stable which,
given past experience is a leap of faith.

AO-10 is currently in its semi-annual eclipse phase where the earth blocks
sunlight just after perigee on each pass.  However, on 01-Sep-97 beginning
at 2020 UTC, AO-10 will have its sunlight partially blocked by the moon
when it is much farther out in its orbit (MA 195-210).  The maximum
occlusion will be 52% and will occur while AO-10 is visible to most of
the US and the Pacific.  Information regarding changes in signal quality
during this time would be much appreciated, and should be directed to
Stacy Mills (w4sm@cstone.net).  Given the good overall illumination at
this time, the effect of the eclipse may not be noticeable.  However, it
is a good opportunity to get a qualitative assessment of transponder output
when we have a relatively good measurement of change in illumination.

		    AO-10  Solar Eclipse by the Moon / W4SM

                     UTC            MA    Dist    	   	     Obsc
        DATE        HH:MM    ONo   /256    deg   SLAT    SLON     %    Type
 1997   Sep   01    20:20   10693  195   0.477   1.0 N  154.9 W  004%   PAR
 1997   Sep   01    20:25   10693  197   0.387   1.5 N  155.0 W  016%   PAR
 1997   Sep   01    20:30   10693  199   0.300   2.1 N  155.0 W  032%   PAR
 1997   Sep   01    20:35   10693  201   0.231   2.7 N  155.0 W  046%   PAR
 1997   Sep   01    20:40   10693  203   0.205   3.4 N  155.0 W  052%   PAR
 1997   Sep   01    20:45   10693  204   0.238   4.0 N  154.9 W  044%   PAR
 1997   Sep   01    20:50   10693  206   0.314   4.7 N  154.7 W  029%   PAR
 1997   Sep   01    20:55   10693  208   0.412   5.4 N  154.5 W  012%   PAR
 1997   Sep   01    21:00   10693  210   0.518   6.1 N  154.3 W  000%   PAR

Because of AO-10 relatively low inclination, its argument of perigee changes
much more rapidly than did AO-13's.  The current value is 144 degrees, placing
apogee in the southern hemisphere.  However, the argument of perigee is
increasing at about 0.28 degs/day and apogee has been moving northward from
its southern most point when the argument of perigee = 90 degrees.  On
approximately 01-Jan-98, the argument of perigee will be greater than 180
degrees, meaning that apogee will cross the equator and progressively move
into the northern hemisphere, peaking when the argument of perigee is equal
to 270 degrees on approximately 01-Dec-98.  So for all of 1998 and virtually
all of 1999, the apogee of AO-10 will be in the northern hemisphere.

More information regarding AO-10 can be found on Stacy's Web page:


Yesterday morning the Store and Forward communications task on the UO-22
On-Board Computer was reloaded by Chris Jackson.  This task included
incremental checksums which should make uploading files slightly faster.
In the old task, once an upload was complete, the spacecraft had to
perform the checksum on the complete file.  Depending on the file
length, this could take quite a long time (maybe a minute for a really
large file!).  With the new task, the checksum is computed on the fly,
while the data is actually being uploaded.  Thus there is no need to
recompute it at the end of the transfer and this checksum delay is
therefore removed.

However, all files that were started before the new task was loaded (around
1000 UTC on 19-Aug-97) will receive a corrupt body checksum error when the
upload is completed.  If the file is uploaded again, it should be accepted.
If groundstations tried to upload a large file that was started before
1000 UTC on 19-Aug-97, then the upload must be re-started.

If anyone should get persistent body checksum errors while uploading files
to UO-22, they are asked to notify Chris Jackson, G7UPN/ZL2TPO at the
University of Surrey (http://www.ee.surrey.ac.uk/EE/CSER/UOSAT/).

[Info via Chris Jackson, G7UPN/ZL2TPO]

Procedures to repair damage to Mir's Spektor module last week went very well.
New power connections made to Spektor are expected to be tested on Monday.

The latest news from Mike Foale via the Amateur Radio station on Mir as
copied by Claudio, IK1SLD in Italy follows:

  Stat   : PR
  Posted : 08/19/97 23:04
  To     : ALL
  From   : R0MIR
  @ BBS  :
  BID    :
  Subject: Mir status

Tnc reset again. After Anatoli successfully docked the progress 
yesterday, manually, we replaced the bad computer that controls the GNC 
of the station,  and reestablished attitude control and solar pointing 
today.  Anatoli and Pavel have completed their EVA training run in the 
suits, and we are now working to have everything ready for the Power 
Connect EVA to take place in the node, on Friday.
Mike. Rodnika.

It has been another uneventful month for OSCAR-11.  During the period 18-July
to 19-August, there were no new bulletins or WOD surveys broadcast by the
satellite.  However, the magnetorquer counters were reset by ground control
during the first week in August.

Excellent signals have once again been received from the 145.826 MHz beacon.
The Mode-S beacon has been heard by Andreas IW0EAC in Rome.  Andreas uses a
60cm dish, 0.6dB NF pre-amp, and a DB6NT converter.  Clear and strong signals
were received on two consecutive passes.  John, LA2QAA, in Frei Island, Norway
also reported reasonable strength signals on July 27, using a 50cm dish, and
G0MRF converter.  Thanks Andreas & John.

OSCAR-11 telemetry has been nominal.  The battery voltage has been maintained
in the range 14.0 to 14.4 volts.  The internal temperatures are slowly
increasing from the minimum values observed at the end of June (battery -0.4C,
telemetry electronics -1.6C).  The battery temperature is now 3.4C, and
telemetry electronics 2.2C.  This is due to a reduction in solar eclipse

A single WOD survey of channels 10, 20, 30, 40 (+Y, -X, +X array currents,
array voltage) dated 25 June has been transmitted during this period.

A single AMSAT-UK bulletin by Richard, G3RWL, has been transmitted.  This
featured Sputnik-1 40th anniversary, MIR frequencies, and RS-10 news.
Bulletins always include current Keplerian elements for OSCAR-11, and
often Keps for satellites featured in the bulletin.

Richard always welcomes short news items for inclusion in the OSCAR-11
bulletin. i His e-mail address is g3rwl@amsat.org

The operating schedule for OSCAR-11 remains unchanged:

	ASCII status (210 seconds)
	ASCII bulletin (60 seconds)
	BINARY SEU (30 seconds)
	ASCII TLM (90 seconds)
	ASCII WOD (120 seconds)
	ASCII bulletin (60 seconds)
	BINARY ENG (30 seconds)

There are also additional status blocks after each bulletin is transmitted,
and between ASCII TLM and WOD.

The Mode-S beacon is ON, transmitting an unmodulated carrier, but telemetry
indicates that it has partially failed, and delivering half power.  Any
reports of reception on 2401 MHz would be most welcome.  Please e-mail

The 435.025 MHz beacon is normally OFF.  However, it can sometimes be heard
when the satellite is being commanded by ground control (ie. within range
of Guildford, UK).  When the 435 MHz beacon is transmitting, the 145 beacon
is normally OFF.  The data transmitted is mainly binary.

OSCAR-11 users are welcome to visit Clive Wallis' OSCAR-11 Web site.  The
site contains some software for capturing data, and decoding ASCII telemetry
and WOD.  There is an archive of raw data (mainly WOD) for analysis, which is
continually being expanded, as new data is captured.  The URL is:


[Info via Clive Wallis, G3CWV,  g3cwv@amsat.org]

On Tuesday August 12, the Shuttle Amateur Radio EXperiment (SAREX) team
received a NASA Johnson Space Center Group Achievement Award.  This award
was given to the SAREX volunteers to recognize the superb efforts put forth
on the STS-94 mission.  The award was given during the STS-94 mission
debriefing session.  SAREX Principal Investigator Matt Bordelon, KC5BTL,
accepted the award for the SAREX team.  The citation on the award reads,
"For your outstanding support during STS-94 that allowed us to contact 17
schools around the world and make multiple contacts with Mike Foale aboard
the Space Station Mir."  AMSAT Vice President for Manned Space Programs
Frank Bauer, KA3HDO, said this to his team of AMSAT volunteers when he
informed them of their prestigious achievement: "The STS-94 crew was duly
impressed with the preparedness of the SAREX schools, the tremendous bridge
contacts, the great contacts with Mike Foale and the smoothness of the
STS-94 SAREX flight operations.  I want to thank you all for your
tremendous support on this and all the activities that you do for SAREX,
Mir and ARISS.  You consistently make me proud".  

[Info via the AMSAT-NA News Service]

Don Heskett reports that the Mars Global Surveyor will begin aerobraking on
or about 11-Sep-97.  The process will be a slow one, and will take until
early next year (possibly March) to change the initial, highly elliptical,
orbit into the desired nearly circular orbit.  A week of measurements may
take place prior to aerobraking to accurately characterize the spacecraft's
initial orbit before the first aerobraking maneuver is performed.

Comments and input for SpaceNews should be directed to the editor (John,
KD2BD) via any of the paths listed below:
WWW       : http://www.njin.net/~magliaco/
INTERNET  : kd2bd@amsat.org, magliaco@email.njin.net

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