NASA dark matter data drops in Patagonia

A NASA mission mapping dark matter was able to retrieve gigabytes of data, after its telescope was destroyed and communications failed, thanks to a recovery system designed by an international team of scientists, including the University of Sydney.

The data was being collected by a Super Pressure Balloon-borne Imaging Telescope (SuperBIT) onboard one of NASA’s stadium-sized balloons, known as pumpkins. 

University of Sydney research associate, Dr Ellen Sirks – who worked on the design, preparation and retrieval of the data recovery system – tells Cosmos the concept was intended as “a sort of failsafe in case the telescope got damaged, or we lost communications, both of which happened”.

The system was MacGyvered from common objects: a Raspberry Pi computer with USB sticks and SD cards, an ethernet connection to the telescope, and a home-made “find my phone” satellite link, all housed in 3D-printed casing inside a foam capsule, tethered by archery release to its own parachute as well as the telescope. 

A report on the system and instructions for its design are published in the journal Aerospace.

The colossal balloon – carrying the telescope and 4 data recovery systems – was launched from Wanaka, New Zealand in April. It flew for 40 nights, successfully circumnavigating the Earth 5.5 times, before landing in Argentina.

The SuperBIT collects an enormous amount of data about galaxy clusters – around 20 gigabytes each night – to infer information about the dark matter surrounding them, Sirks says.

To avoid the risk of total data loss, satellite communications are usually used to retrieve data from telescopes mid-flight. But this can be expensive and slow, Sirks says. 

The data recovery system was designed as an alternative backup, downloading data onto the SD cards along the way, to be released to Earth, while the telescope and balloon continued their journey.

Sirks also developed some software to predict where the 1.3 kilogram data recovery systems might land, taking into account the time of release and weather forecasts. “As you can imagine, a lot of countries don’t generally like it when we just drop things,” she says.

Originally 4 data recovery systems were onboard. The team were able to retrieve 2 containing more than 200 gigabytes of data, which landed in Patagonia, Argentina. 

The other 2 remained on board, one intentionally, and the other because it failed to react to commands after launch.

Sirks says when each system landed it sent her a GPS location by email. “So we had a fairly good idea of where they were. We asked the local police to help us because it was in Patagonia, in quite rough terrain. They went there with their jeeps and helped pick it up for us.”

While the data collected is yet to be published, Sirks says, “we’re very happy with the resolution and we’ve seen some interesting things already”.