AO-51 – End of Mission

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.

The 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.

It’s not so much a problem of not enough illumination, but more that we are running on 3 or 3.5 cells, and we need ~4 to make the transmitters work. There may be some points during the orbit when the V gets high enough for the transmitter to come on at low power, but that is conjecture only. We don’t know when or really even if that will happen.

If a cell opens up in the future, the IHU will immediately crash upon eclipse, and the battery voltage -may- rise to whatever the panels can provide. If this happens we may be able to restart the IHU and get a transmitter running, but it will only last until the next eclipse.

For the AO-51 Command Team,

73, Drew KO4MA
AMSAT-NA VP Operations

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