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[jamsat-news:668] * SpaceNews 27-Oct-97 *

* SpaceNews 27-Oct-97 *

BID: $SPC1027


                        MONDAY OCTOBER 27, 1997

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

The Mars Pathfinder operations team is continuing its efforts to reestablish
communications with the Pathfinder lander.  Although they are experiencing
communications difficulties, the team is confident that the spacecraft is
still operating on the surface of Mars, according to Mission Manager Richard
Cook.  The last time they were able to send a command to the Pathfinder
lander instructing it to transmit a signal back to Earth was on Sol 93,
which was Tuesday, 07-Oct-97 at 14:21 UTC.

Team members suspect that the spacecraft may not be receiving commands from
Earth properly because the lander's hardware has become much colder than
normal.  In regular operations, when the lander's transmitter is turned on,
spacecraft hardware warms up sufficiently to operate normally.  Since the
transmitter has not been on for several days, engineers suspect that
temperatures within the lander are considerably colder than normal.
Predicted internal temperatures drop to as low as -50 C (-58 F) in the
early morning and only rise to about -30 C (-22 F) in the late afternoon.
These temperatures are about 20 C (38 F) colder than the coldest previous
operational temperatures.

The lower temperatures cause the spacecraft radio hardware to operate outside
the range of radio frequencies that ground controllers have used in the past.
During the past three weeks the operations team has been transmitting to the
spacecraft at a lower frequency and sweeping through a wider frequency range,
a technique that has been used on other missions to attempt to cause the
spacecraft receiver to lock on to the transmitted signal.  Once ground
controllers finish this, they send commands instructing the lander to
turn on its transmitter and send a signal back to Earth.

To be certain that they investigate all possibilities, team members are
also consulting with experts knowledgeable about the radio and other key
elements of the spacecraft.  They have identified some new scenarios that
are being pursued to regain communications.  These recommendations include
doing more testing of the engineering model hardware in the laboratory
to better understand how the spacecraft might be behaving.  Another
recommendation has suggested shifting and increasing the range of
frequencies being swept through much more than previously attempted.

According to Project Manager Brian Muirhead, the possibility exists that
an unrecoverable problem may have occurred.  Team members expected that,
once the lander's onboard battery died, cold and thermal cycling could
result in a failure of some other element of Pathfinder and thereby end
the mission.  "However, the Pathfinder project is funded to continue
operations until August 1998, and the team will continue to do everything
possible to reestablish communications until all options have been
exhausted," Muirhead said.  The mission has already exceeded all
of its goals in terms of spacecraft lifetime and data return.

The science team, meanwhile, continues to process and analyze the large
volume of data sent back by Pathfinder's lander and rover.  Further science
products are planned and new results will continue to be presented as they

[Info via JPL/NASA]

The current Mir crew is still very busy working and experimenting in their
Lab in space.  American Astronaut David Wolf, who is currently living on
board the Russian Mir complex, said he is working 14-16 hours a day.
Judging by the tone in his voice, he is enjoying every minute of this stay.
During an Amateur Radio contact with David Wolf, Miles Mann, WF1F asked
when he thought he could put the Amateur Radio 2-meter station back on the
air.  David said he had 6 items on this top priority list, and Amateur Radio
was currently number 6.  Miles assured David that everyone on earth
understands his current work load, and that the Amateur Radio experiment
(Personal Message System, PMS) is a low priority experiment.  David said
he would like to move the PMS experiment higher on this list of things to
do.  He said he is planning on reading the existing 40 mail messages waiting
for him when he gets some free time.  He is also planning on putting out
a mail message to "ALL" on the PMS when he gets some free time.

In the mean time, the PMS 2-meter station has been turned off.  The small
13k mailbox is completely full.  The amount of time required by the crew
to read, reply and delete the daily load of mail is approximately 30 to 60
minutes per day, just to keep the mailbox open for the public.  At the
present time, the crew's work load is just too heavy to support this type
of time investment towards a non-essential project.

There are a few inconsiderate Amateur Radio stations who feel the crew's
primary job is to read and reply to packet mail all day long.  Most of us
understand this is not the crew's job.

The SAFEX II 70 cm repeater is still turned off.  It is not known when the
this experiment will be turned back on, but we do know the crew is still
trying to build up power reserves in the batteries of the space station.
The space station is now getting power from all solar panels, except the
one that was damaged by the Progress truck collision.

The crew performed an internal space walk last week.  The crew repaired 5
data cables, and attached them to the special air tight feed through
connectors on the new Specter hatch.  (Experiment: Put on your thickest
snow gloves and winter jacket.  Then try to install a new coax connector on
a cable.  This is what is was like trying to repair the data cables on Mir.)
The crew now can remotely steer two more of the Spectr module solar panels.
An external space walk is planned for some time between October 30 and
November 1.  There are three more Space walks planned this year.

[Info via Miles Mann, WF1F]

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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