ARISSAT-1 Battery Issues

The ARISSat-1 battery performed as expected during the first week of operation. Lower voltages during eclipse began to show up in the telemetry on 10 Aug 2011. The voltages during eclipse have continued to decline causing the satellite to reset and go into Emergency power mode on 12 Aug.

After reset the satellite MET (Mission Elapsed Timer) goes to 000, waits during the 15 minute TX delay, the power management software checks the current voltage and power values and determines what power mode to operate the satellite. The power mode is re-determined at fixed intervals, especially during illuminated periods to provide the most transmitted signals while protecting the battery.

High power mode provides continuous transmission when sunlight is charging the battery. If the satellite has entered low power mode it will transmit for 40 seconds and remain idle for 2 minutes when in eclipse, or when the battery voltage is low.

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About ARISSat-1
ARISSat-1 is a microsat developed as a follow-on to the SuitSat-1 project. The satellite was launched to the ISS on January 28th, 2011, with deployment into space during an EVA (spacewalk) on February 16, 2011.
The satellite will downlink live SSTV images from four onboard cameras as well as 24 greetings in 15 languages on the FM voice frequency 145.95 MHz. The BPSK-1000 sig downlinks as SSB on 145.920 MHz, with the CW signal below the BPSK signal to be used as a tuning indicator for the BPSK signal. Telemetry and amateur radio callsigns of those instrumental in amatuer radio in space will be transmitted at 145.919 MHz. For the amateur radio operators there is a 16kHz wide transponder for two-way contacts. All of the transmissions and receicvers use newly created software defined radio technology.
The BPSK-1000 signal will include alternating telemetry and experiment data packets. Telemetry data will include spacecraft subsystem information such as temperature, voltage and current measurements. The Kursk State University experiment will be sent as 5 packets for a total of 2k of data. The data is collected for 90 each day. This experiment will sample the change in vacuum as the satellite slowly re-enters the atmosphere.