Here's a short report I wrote on one of the QB50 satellites flying on this mission.
On Monday, 12 September 2016, I had a chance to see the final touches being made to SUSat. The 2U cubesat is one of three Australian QB50 satellites that are scheduled to be launch in the OA-7 Cygnus spacecraft to the International Space Station (ISS) on 30 December 2016. The QB50 satellites will then be deployed from ISS in two batches in February and March 2017.
Attached are photos of Dr. Matthew Tetlow, the project leader of SUSat, in front of the clean air box where SUSat is being worked on. In the close up photo, you can see the dummy Ion and Neutral Mass Spectrometer (INMS) next to SUSat on the right. The real INMS had been test fitted to SUSat, but then sent back to Mullard Space Science Laboratory (MSSL) where further work needs to be performed on the instrument. The INMS will be used for measuring the thermosphere around the Earth.
You can see two cables going to the top of SUSat. The cable going to the back is the programming and power cable. Dr. Tetlow was in the process of reprogramming the software that controls the Sun sensors. The cable going to the front is the Remove Before Flight inhibit cable. When plugged in, SUSat is in a safe mode. The INMS is fitted to the base, which also has several contact switches. When SUSat is deployed, the switches tells SUSat that it can now power on and start working. Unfortunately, one of the original switches failed during vibration testing. The switches have now been replaced by more simpler and robust units, having successfully passed testing on the other Australian QB50 cubesats.
Commercial solar cells from Azurspace and Spectrolab are used. There are five panels, one each on the four main sides and one small panel on top. Each side panel has four triple-junction Gallium Arsenide solar cells with the top panel having two cells, for a total of 18 cells. Each large panel is capable of generating 5.2 Watts, although SUSat only has an average power of around 4 Watts, with a 2 Watt minimum operating power. Each panel also has a small Sun detector. You can see one of these in the middle on the right hand side, below the orange blob.
On the left, you can see one of the two Sun sensors (the round object) and one of the two GPS receive antennas (the square object) from Antcom. The other Sun sensor and GPS antenna are on the other side of SUSat. At the top you can see one of the two yellow communication antennas in the stowed position. The other antenna is on the other side. This is simply your everyday measuring tape that has been cut to size! One antenna operates at VHF (Very High Frequency) and the other antenna at UHF (Ultra High Frequency). Two antennas and frequencies are used for redundancy.
The total mass of SUSat is 1.96 kg plus or minus 40 grams, which is the uncertainty of the INMS mass. I'd like to also acknowledge all the students from the University of Adelaide who have worked hard to make this possible as well as Dr. William Cowley and his team from the University of South Australia for providing the communications electronics on the satellite and the ground station.