For the next ten years, cubesats missions continued to be launched at a rate of few per year. Many of the cubesats were continuing to be built by university teams, but some came from government space agencies and emerging New Space industry players. There were no special purpose launch vehicles for this type of satellites, so users had to rely on rideshare opportunities and use low-cost providers that relied on refurbished ICBMs as launch vehicles.
But this kind of rockets don’t have the best reliability record. Sometimes it caused substantial setbacks, such as one that happened in July 2006 when Dnepr space rocket crashed soon after launch, bringing down 22 cubesats with it. While it was obviously disappointing for mission designers, many of those cubesats had flight spares available and were relaunched in the later years. Typically, a small budget cubesat of this period had an imaging camera and one other additional science experiment, such as radio communications device or particle detector but sometimes more unusual mission. In this chapter we’ll try to describe a few of more interesting examples.
The first the mission on our list was called CUTE 1.7+APD. It was a 2U cubesat built by a Japanese team from Tokyo Institute of Technology. It had an interesting distinction of using a Windows CE PDA from Hitachi as a primary onboard computer. An was launched in February 2006 and operated successfully for about a month. However, the consumer PDA is clearly not the best possible option for a space mission on-board computer. The satellite stopped responding in March of the same year, most likely due to radiation-triggered hardware fault.
Other interesting missions during these years were various tests of tethers – wires used to connect structures in space. One such research program was MEPSI, and it included a number of nanosatellites designed by DARPA. While not implemented in any standard form-factor, they were pretty close in dimensions and mass to regular cubesats. There were deployed in pairs from Space Shuttle Endeavour in November 2002 and again from Space Shuttle Discovery in December 2006. The purpose of these missions was to test radar detection of two satellites connected by tether. This program was terminated before the conclusive results were obtained but the second pair operated in space for a few days at least.
MAST was another experiment with tethers, this time built by Tethers Unlimited and launched in 2007. It was composed of a mother and daughter satellites connected by 1 km long tether that was supposed to deploy after launch. The daughter satellite would climb along this tether back and forth to prove feasibility of this architecture. But unfortunately, this mission ended in failure as well. The satellites were operational, but the tether didn’t deploy. Here is the illustration of how it would look in deployed state:
As a rule, mechanical failures are quite common in space environment. Cold welding or outgassing can interfere with moving parts and connections or stick them together. Dynamics of mechanical structures in microgravity and vacuum conditions are very different from the ones on the ground. Testing these aspects requires specialized facilities. There is a tower in Bremen, Germany that allows to drop various experiments for a few seconds of microgravity. And one of our teammates has actually used this facility for his own research project, namely Drop Your Thesis. But this will be a story for another time.
Astrobiology (biological experiments in space) was another emerging research area that cubesats were used for.. The first mission of this kind was GENESAT, a 3U cubesat launched in December 2006, that was also the first cubesat from NASA. Its mission was to measure levels of protein activity in cultured bacteria. It was using a number of small cells filled with bacterial cultures that were brought to life in space using the sugar solution. Then special LED triggered the protein to emit some level of light and that was the essence of this biological experiment.
The next important area tried via cubesat technology was solar sail technology. This type of propulsion holds a lot of promise for space exploration, both now near and in the future. It also helps that this tech can be tested on a smaller scale before building full-scale solutions. The first solar sail mission was NanoSail-D. It gained a bit of infamy as it was attempted to be launched on SpaceX Falcon 1 in 2008. But unfortunately, it was launched on the 3rd flight of Falcon 1 which wasn’t a successful one. This also highlights the importance of having a flight spare – because it was launched as NanoSail-D2 in 2010, and this time it was a successful mission. Notably, the launcher used (Minotaur IV) was a converted ICBM, but an American one. That cubesat was deployed in a slightly unusual manner, from inside another satellite called FASTSAT. There was a bit of drama in this story! The satellite didn’t deploy immediately and was stuck to a mother satellite for a while. But somehow is able to detach itself a few weeks later and it became operational. It had no solar panels, so it was operating on batteries only and didn’t live for long. But nevertheless, it was a successful mission and had the honour of the first successful cubesat mission, equipped with solar sail.
To conclude the story, it should be mentioned that between in years 2003 to 2012 the rate of cubesats launches was relatively low. A few per year usually, with up to 25 in year 2012, excluding the unsuccessful launches. The big breakthrough in launch numbers came next year. But this will be the topic for the next part of our cubesat history series.
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