November 21, 2021, marks the eighth birthday of the FUNcube-1 CubeSat. Remarkably the tiny spacecraft, launched from Russia on November 21, 2013, continues to work well having travelled more than a billion kilometres in space.
During the past couple of months, the spacecraft’s orbits have been running just along the edge of the terminator. Initially we had effectively full sun with no eclipses but at the beginning of this month it appears that the solar panels were not receiving enough solar radiation to keep the battery fully charged.
FUNcube-1 was transmitting continuous high-power telemetry and was therefore consuming maximum power. The screenshot above is from the AMSAT-UK/BATC groundstation at Goonhilly Earth Station. The FUNcube Dashboard shows the rapid decline in the bus voltage from an already below normal 8.0V down to 7.8V. The spacecraft was switched to “safe” mode on the afternoon of November 18th. This reduced to total power consumption by almost 50% and, as can been seen, the spacecraft is again in a happy “power positive” situation.
Although safe mode provides less than 20mW of downlink RF, it is remarkable how many stations are still receiving and decoding the 1k2 BPSK telemetry. This is a good point at which to say a massive thank you to the many many stations around the world who, even after eight years, are continuing to submit their data to the FUNcube Data Warehouse. It really is valuable to the team and has really helped us to understand what is going on up there!
We will continue to monitor the telemetry over the next few weeks and plan to return FUNcube-1 to nominal autonomous operation, with the transponder on when the spacecraft is in eclipse, as soon as possible.
Interestingly, it appears that we will not be having any more “full sunlight” periods for the foreseeable future., however those that we have experienced have provided some good data on how hot a 1U CubeSat can become in such circumstances!