AO-51 not responding to commands

AO-51 Echo LaunchNovember 29, 2011 – AO-51 not responding to commands

It is with a heavy heart I report that AO-51 has ceased transmission and is not responding to commands. The last telemetry data indicated that the third of six batteries was approaching failure to short, and observations indicate the voltage from three cells is insufficient to power the UHF transmitters. The IHU may continue to be operative. Initial tests with the S band transmitter were also not positive, although more attempts are in order. We have tried leaving the satellite in an expected state where if voltages climb high enough, the 435.150 transmitter may possibly be heard.

AO-51 AssembledThe command team will regularly attempt communications with the satellite over the coming months (and years). There is always the possibility that a cell will open and we could once again talk to our friend while illuminated. Thanks to all who helped fund, design, build, launch, command, and operate AO-51. It’s 7 year mission has been extraordinary. Please support AMSAT’s Fox-1 project, and other AMSAT projects worldwide with your time and money.

For the AO-51 Command Team,

73, Drew KO4MA
AMSAT-NA VP Operations

 

Longer Eclipse Periods Affecting AO-51

Amsat Oscar AO-51AO-51 Command Stations report that the seven year old spacecraft is now shutting down its transmitter after losing sunlight on its solar panels during eclipse periods. Two of the six battery cells are now dead. Since July 31, 2010 AO-51 has maintained continuous and stable operations due to careful tuning of its power settings.

The AO-51 Operations Team reported on November 25 that the on-board computer (IHU) crashed between 1815 and 1945Z due to low voltage. This happened after a few days of intermittent and unpredictable operation.

AO-51 Control Operators Mark Hammond, N8MH and Drew Glasbrenner, KO4MA reset the satellite and started the repeater back up around ~2030Z. Satellite operation was set to the following:

Uplink: 145.880, no PL tone required
Downlink: 435.150 at about 300 milliwatts

Satellite EclipseDrew reported that telemetry data showed the battery voltage was low, around 4.9v, with cell 1 less than 1 volt. The impending third cell failure will likely end continuing operations, particularly if it fails shorted as the others have. At present there remains little margin as the operations team has observed the transmitters cutting off around 4.7 to 4.6 volts prior to the last reset, in eclipse.

Please submit your AO-51 reports to the OSCAR Status Web Page: http://oscar.dcarr.org. The command stations monitor this for changes in the operation. While worldwide participation is good, more reports from US operators are appreciated.

Eclipse periods, which are expected to reach 30 minutes by the end of 2011, are causing AO-51 to shut itself OFF due to low voltage.

Please support AMSAT-NA and the other AMSAT groups around the world, and help us get new satellites into orbit. Projects like Fox, FunCube, P3E, and Kiwisat need your financial support to keep our amateur satellite fleet flying.

You can keep up with the latest AO-51 Command Team news at:
http://www.amsat.org/amsat-new/echo/CTNews.php

Source: Amsat NA

AO-51 IHU Crash

Satellite IHUAMSAT-NA VP Operations Drew Glasbrenner KO4MA reports on Friday’s IHU crash on the Amateur Radio satellite AO-51. Sometime between 1815 and 1945Z November 25, AO-51′s IHU crashed. This happened after a few days of intermittent and unpredictable operation.

Mark N8MH and I reset the satellite and started the repeater back up around ~2030Z, and lowered the output power to about 300 milliwatts. Battery voltage was low, around 4.9v, with cell 1 less than 1 volt. This is very troublesome, as the impending third cell failure will likely end our continuing operations, particularly if it fails shorted as the others have. We’ve also observed the transmitters cutting off around 4.7 to 4.6 volts prior to the last reset, in eclipse.

We’ll do what we can, but her days are short. Let me ask once again for more reports, especially from the US operators, to the Live Satellite Status webpage. The command stations monitor this for changes in the operation of AO-51, and while worldwide participation is good, few US operators post to it.

Update Nov 27, 2011:

AO-51 still off-air. Satellite is not responding to commands, we suspect that the 3rd cell has failed short, therefor insufficient voltage for the transmitter.

AO-51 to support 54th Jamboree

AO-51 to support 54th Jamboree On The Air October 15-16, 2011.

54th Jamboree badgeThe AO-51 Command Team is happy to announce support of the Scouting Jamboree On The Air (JOTA) during the weekend Oct. 15-16, 2011. The AO-51 satellite will remain in its current configuration, with an understanding that contacts involving Scouts will be given first priority during this period.

The current operating mode of AO-51 is as follows:

Uplink: 145.880 MHz FM (No PL tone)
Downlink: 435.150 MHz FM

The World Scouting Organization in Switzerland posted JOTA information on their web: www.scout.org.