On March 22, the FUNcube-1 (AO-73) CubeSat will be commanded into continuous transponder mode for one or two orbits so we can assess the effect of lower power being radiated by the sat on the battery temperature. We expect the satellite to be put into full time transponder mode (aka amateur mode) during the first morning pass on Saturday, March 22 over the UK, at approximately 0930 UT.
We are aware that the on/off timings for the transponder are not now ideal, due to seasonal changes. In the coming months the situation will get worse such that in June the transponder will only be available for very short periods in the Northern Hemisphere.
We are therefore planning to alter the schedule such that the transponder is on continuously at weekends after approx 1900 UT on Fridays, to Sunday evening. This will give radio amateurs a greater opportunity to use the transponder. Unfortunately there is no way of automating this schedule, so its maintenance will rely on the availability of command stations.
Before implementing this schedule, it is necessary that we characterise the effect of maintaining transponder mode for long periods of time. We expect that the space craft will be slightly colder than when transmitting at full power, as the heat generated inside the spacecraft by the PA will be less.
We are concerned that this lowering of the temperature may bring the battery temp lower than is advisable. Its specification is that it should not be charged if its temperature is below -5 degrees, or some damage might be done to the battery. Currently the minimum temperature we see that the battery reaches is approximately -2 degrees.
If you notice that the transponder is open on March 22, please feel free to use it.
Please note that we have learnt from experience that commanding the sat is not an exact science, and that not all commands sent are received by the satellite, probably due to interference. We will announce on AMSAT-BB and on the FUNcube web site the progress of our tests. We would be very grateful if as many listening stations as possible receive the telemetry (TLM) using the Dashboard software and forward it to the Data Warehouse on Saturday, March 22. Thank you.
73 Jim, G3WGM
FUNcube website http://www.funcube.org.uk/
FUNcube Yahoo Group https://amsat-uk.org/funcube/yahoo-group/
FUNcube Forum http://forum.funcube.org.uk/