Space-bound CQT experiment survived rocket explosion in working order
The recovery of SPEQS boosts team's confidence in its rugged design
27 August 2015
On 28 October 2014, Alexander Ling had an experiment in a satellite on a rocket ready to go to the International Space Station (ISS). Then this happened...
But all was not lost. Earlier this year, the team learned that the explosion that destroyed the rocket did not destroy CQT's Small Photon-Entangling Quantum System (SPEQS). The satellite containing SPEQS was found on a beach. Now tests this month have shown that it's still working. The news is reported in the 27 August edition of Singapore newspaper the Straits Times. Update: technical details were published 10 May 2016 in the journal Scientific Reports.
"We don't know how the device survived the explosion, but this has validated the years of careful design that was put into the project," Alexander told the Straits Times. "We are now very confident that if our next device reaches space, it will work." The team have three flights for new copies of the device coming up before the end of the year: one on a weather balloon, one on a sounding rocket and one more satellite launch.
The device is designed to create quantum entangled light particles for use for secure communication. The long-term view is to be able to beam such photons from a satellite down to Earth or to other satellites. This could allow quantum cryptography over longer distances than is possible today. Quantum cryptography using entangled photons sent through optical fibres or through air at ground level only works over 50km or so, because the photons get absorbed.
Destined for space
The device in the unmanned Orb-3 mission last year was the first SPEQS destined for space. Once it reached the ISS, the satellite would have been launched into orbit by the station's astronauts. The Orb-3 mission was a commercial launch under contract to NASA to send supplies to the ISS.
GomSpace tweeted the news of the satellite's survival.
The sandwich-sized package of optics and electronics had already been through extensive tests to make sure it was robust enough to survive launch and conditions in orbit. But the team didn't expect SPEQS to survive the fireball they saw on NASA TV. "I thought it would have been smashed into a thousand pieces or melted," says Cliff Cheng, an engineer on the project.
In the spirit of April Fool's, some of the team wrote a paper imagining the extreme heat and forces their device may have suffered and posted it to the arXiv preprint server. The abstract jokingly concluded: "Our results show that while such a device may tolerate launch into orbit, operation in orbit and casual mishandling by graduate students, it is probably unable to survive the forcible disassembly of a launch vehicle at the top of a ball of rapidly expanding and oxidising kerosene and liquid oxygen."
Turns out they were wrong! After the satellite was found, it was returned to the company GomSpace ApS in Denmark. GomSpace had built the satellite, called GOMX-2, including SPEQS as one of the payloads. The satellite had to be cut out of its launch mechanism, suggesting it had experienced a forceful impact. But there was little damage to the satellite itself – only slight dents and some sand – and it ran without repairs.
After GomSpace sent data from the recovered satellite, Alexander says his team stayed up late into the night to study the results. "We compared SPEQS data after the explosion with data collected before it was placed on the rocket. So far nothing appears broken and we conclude that it has survived."
The team won't reuse the device or recycle its components because of what the device has been through. As the team's contact Dennis Elgaard at GomSpace said, "It never made it to space, but at least it passed the shock test of the century!"
The next launch to space, in December, will mark a second attempt to get SPEQS into orbit. Flights on a weather balloon in October and sounding rocket in December will test SPEQS-2, an iteration on the design with more advanced capabilities. Beyond that, the team has funding from Singapore's National Research Foundation in a five-year project to build their own satellites. They aim to have the first SpooQy-Sat ready in 2017.