AMSAT-NAAMSAT News Service

November 9, 2001

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AO-40 Update

Command station team member Stacey Mills, W4SM, reported the latest AO-40 information to ANS:

Recently, a short program was uploaded to cycle the power on and off to the S-1 transmitter. The purpose of this test was to determine if the controller circuit to the transmitter (or the transmitter itself) had an intermittent problem relating to power up. The program turned the power on and off each second. When on, it checked to see if the S-1 transmitter was actually drawing any current. If so, the program would stop, leaving the S-1 transmitter on.

The program ran for approximately 45 minutes (thus the power was cycled on and off approximately 1,350 times). During this time, the S-1 transmitter was never detected to be drawing current.

Accordingly, control stations now assume that the S-1 transmitter cannot be recovered. Nonetheless, ground control stations will repeat this test from time to time on the remote chance that an intermittent problem may have corrected itself.

This same test will also be performed on the solid state component of the X-band transmitter shortly.

The V-band transmitter has also seen additional testing. The V-band transmitter draws power and warms up, but no output signal has been detected. Additional testing will be done, including listening with EME class stations. Though this may provide evidence for what's wrong with the V-band transmitter, however, ultimately it also appears lost.

Currently, AO-40 is at an ALON/ALAT of 6/2 with station keeping underway. Orientation is against the mystery effect. Following this AO-40 will be moved back toward 0/0.

Magnetorquing has been decreased from MA-224/32 to MA-240/16.

W4SM also reports that control stations have encountered a problem with the middle beacon (and passband) not returning to the air after a RUDAK session. This was traced to problems with the S-2 transmitter AGC due to the schedule routine disconnecting RUDAK, followed by a brief delay with no input to S-2.

The AGC could did follow this rapid fluctuation and would occasionally go into a low power mode requiring the transmitter to be recycled. The temporary solution to this was an intermediate schedule line which turned the middle beacon on for one MA before the RUDAK was disconnected.

The schedule routine in the IHU has now been modified to correct this situation.

Additional testing, including L-band uplink to S-2 downlink, U-band, K-band only downlink, S-band uplink, etc., are currently being planned for the future.

Testing and development continues on the 3-axis control system, to account for significant changes in the final orbit, the mystery effect, and the loss of some sensors. Expect further feasibility testing and announcements on this shortly.

AO-40 is approaching the end of a favorable solar angle, within one month we will have to either initiate 3-axis control or off-point AO-40 for several months until the solar angle improves. No shift to 3-axis control will be made without adequate testing of a mechanism to revert back to spin control.

AO-40 is currently in a long period during which the Earth eclipses the Sun near perigee. These actually began about August 28th, and will rapidly increase in length. The will continue well into June 2002.

For the current transponder operating schedule visit http://www.amsat-dl.org/journal/adlj-p3d.htm

AO-40 activity continues. Jeff, K7XQ, recently made his first AO-40 contacts, working JA5CU/1, JA6QT, JR1ASH, JA1UKI, BV2SR and JA8AXQ.

Stay tuned to ANS, the official source of AO-40 information.

[ANS thanks AMSAT-NA for this information]

PCSat Update

Bob Bruninga, WB4APR, tells ANS that PCSat has completed its first month in space and is performing well in its planned mission of mobile position and status reporting. "We have seen over 140 users in the European footprint and a comparable number in the U.S., as well as stations in Australia," said WB4APR.

PCSat is currently in its maximum eclipse phase and the 9600-baud UHF receivers are turned off. The GPS system also remains off except for a short period when in-orbit over the command station.

WB4APR told ANS that users seem to be following the established guidelines, thus assuring that everyone gets a fair chance. Many mobile stations seem to access PCSat reliably.

All of PCSat's hardware is working well except for the loss of the experimental Z solar array. The only un-exercised features are the LED communication experiment and the onboard synchronizer. Bob reports that as optical conditions improve control stations will try to flash the LED's for visual confirmation.

For more information, visit the PCSat web site at http://www.ew.usna.edu/~bruninga/pcsat.html

[ANS thanks Bob Bruninga, WB4APR, for this information]

ISS Update

The Expedition-3 crew, Commander Frank Culbertson, Pilot Vladimir Dezhurov and Flight Engineer Mikhail Tyurin, continue to make preparations for the third and final space walk of their mission (scheduled for November 12th). This is the fifth space walk to take place from the International Space Station (ISS).

The Expedition-3 crew is scheduled to return to Earth in December on shuttle mission STS-108, which will launch their Expedition-4 replacements. The space shuttle Endeavour is targeted for lift off (STS-108) late this month. A firm launch date will be established following a Flight Readiness Review by shuttle and station managers.

In addition to preparing spacesuits and equipment for their Monday spacewalk, the Expedition-3 crew has continued scientific investigations aboard the station this week. These investigations include measuring space radiation aboard ISS and growing crystals that may help researchers better design drugs to fight diseases such as diabetes.

With systems operating normally, the station is orbiting the Earth at an average altitude of 247 statute miles, roughly every 90 minutes.

[ANS thanks NASA for this information]

ANS in Brief

ANS news in brief this week includes the following:

Weekly Satellite Report

Link to the weekly report on satellite ...

All Satellites
ISS . RS-12 . RS-13 . RS-15 . AO-10 . UO-11 . UO-14 . AO-16 . DO-17 . WO-18 . LO-19 . FO-20 . UO-22 . KO-23 . KO-25 . IO-26 . AO-27 . FO-29 . TO-31 . GO-32 . SO-33 . PO-34 . SO-35 . UO-36 . AO-40 . SO-41 . SO-42


Please send any amateur satellite news or reports to the ANS Editors at ans-editor@amsat.org, or to ANS Editor Dan James, NN0DJ, at nn0dj@amsat.org.

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This week's AMSAT News Service bulletins were edited by AMSAT  News Service editor Dan James, NN0DJ.

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