Today, November 21st 2017, marks the fourth birthday for FUNcube-1 in orbit.
FUNcube-1 was launched at 07:10 UTC on November 21st 2013 and its first signals were received immediately after deployment over the Indian Ocean by amateurs in South Africa. Since then it has been operating continuously in either its education mode or, with the transponder active, in amateur mode when in eclipse and at weekends.
The spacecraft has spent the four years in space orbiting the earth at between 640 and 580 km and has now travelled around the earth more than 20,000 times. That represents a distance travelled of approaching 500 million miles.
Up to now, each of the orbits has been spilt approximately 65% in sunlight and 35% in eclipse. This has resulted in the temperatures inside the small spacecraft varying by about 25°C during each orbit.
During the recent AMSAT Colloquium, Wouter, PA3WEG, during his presentation about the FUNcube project mentioned that the power available from the solar panels has been slowly increasing since launch. This observation led the team to do some further investigations as to the cause.
Although the launch was into a nominally Sun Synchronous orbit, over time this has drifted and the spacecraft is now entering a period when it will be in the sun for longer periods during each orbit.
The exact details are still being determined, but it seems likely that, starting from January 2018, there will be periods when the spacecraft will be in the sun for all, or almost all, of its orbits. Of course, this means that the on-board temperatures will be much higher than we have previously experienced in flight, although we have some test records from pre-flight thermal air testing that were undertaken after integration.
The key will be to discover what the equilibrium temperature will be internally. For comparison, AO85 has already “enjoyed” periods of full sun and its internal temperatures have reached up to around 55°C.
So the next few months will be quite an exciting time for the team! We remain extremely grateful to everyone is using the spacecraft for both its educational and amateur missions. Of course we are also very very grateful to those who are downloading the telemetry and uploading the data to the Data Warehouse. It continues to provide a unique record of “life on board” a 1U CubeSat in space.