Back in April, the first three Australian-built satellites launched in 15 years all initially failed to deploy correctly. However, a combination of smart diagnosis, international teamwork, and amateur assistance has seen two of them successfully rebooted. Given the tiny size of Australia's space endeavors, the team responsible is understandably both thrilled and relieved, although some may consider their comparison of the operation to one of the highlights of the space race a little over the top.
On April 19, 28 satellites weighing less than 2 kilograms (4 pounds) were launched from Cape Canaveral to the International Space Station, where they were released in groups of three. Known as "cubesats", these small satellites are part of the QB50 project. They come from 18 countries and will be independently operated while collaborating to study the lower thermosphere – the area above the atmosphere 200-380 kilometers (320-600 miles) above the Earth's surface. A further eight cubesats were launched by other means, and 14 more will be added later.
It is hoped the project will demonstrate the potential of small, low-cost satellites to tackle important scientific questions. However, things started badly when no signal was detected from the three Australian satellites in the mission, along with many of the others.
“It was like something out of Apollo 13,” said Dr Elias Aboutanios, project leader for UNSW-EC0, the first satellite the space station deployed, in a statement. “Our satellite was orbiting at 27,000 km/h (17,000 mph) almost 400 kilometers (250 miles) above our heads. We couldn’t see it, couldn’t inspect it, and had almost no data to work with. So we were busting our heads trying to figure out what could have gone wrong, and how to regain contact.”
Before QB50, Australia had only launched two home-made satellites, the last of these in 2002. There is no coordinated plan to address this and some Aussies fear the ultimate indignity of seeing New Zealand pass them in the space race. The situation hurt.
The Australian Center for Space and Engineering Research (ACSER) was responsible for two of these satellites and decided the most likely cause of the problem was the failure of antennas to extend after deployment. This, in turn, was blamed on batteries that had discharged over the nine months the satellites had waited to be sent into orbit. The satellites' solar panels should have fixed that, but the ACSER team feared the panels' energy was being squandered trying to reorientate the satellites and extend their antennas before enough could be saved to do the job properly.
The cubesats needed to be reprogrammed to power down and wait for the batteries to fully charge, but how could the instructions be received through unextended antennas?
To get out of this vicious circle, the team needed a more powerful radio-telescope, one capable of detecting the weak signal sent by an unextended antenna, and pushing a message back with enough power for the QB50 satellites to receive. Such equipment is rare, and usually otherwise occupied, but one example is the Dwingeloo radio telescope, built in the 1950s and taken over by amateurs when its professional days were done. Sound technician Jan van Muiklwijk offered to operate Dwingeloo for ACSER, but could only do it on weekends.
Van Muiklwijk managed to detect a weak signal from one of the satellites, INSPIRE-2, and sent the instructions. The following day INSPIRE-2 was found to be operating as intended, with a signal strong enough to be detected by ham radio operators, let alone ACSER's receivers.
The other two Australian cubesats remained silent, however, along with some of the others. Eventually, the ACSER team tried listening in to other satellites launched at the same time, and found the ISS had mixed up some of the cubesats launched together. They'd been tracking The University of Colorado's Challenger satellite, but listening at the frequency for their UNSW-EC0 cubesat. When ACSER tried UNSW-EC0's frequency for the satellite labeled Challenger, they picked up a weak signal, which they were able to boost to full strength by repeating the work done on INSPIRE-2.
Of the 28 QB50 satellites launched from the ISS, 20 are now operating as intended, but eight remain silent, including the third Australian member of the team, SuSAT. Work continues to bring all of them eventually online.
