The SuperBIT can collect several gigabytes of data per night, and relaying it back to Earth is not just complex but expensive. One idea put on the table was to periodically offload the data via radio or microwave from an under-flying plane. The balloon’s remote position over the ocean though would make this logistically difficult.

Paul Clark, head of engineering at Durham CfAI, said: “Our slightly crazy idea is to carry out data drops whenever the balloon passes over land. Imagine a TB flash drive being dropped from the telescope gondola and coming down to the ground on a parachute. The challenge then is to track the data payload as it descends and find it once on the ground. That’s where the Iridium 9603N comes in.”

The SuperBIT beacon that tracks the payload uses a GPS receiver and an altitude/pressure sensor integrated with the Iridium 9603N modem. The beacon design has proved reliable, even at high altitudes where the temperature falls below -50C and the air pressure is very low. Battery chemistry has also been carefully chosen to withstand the extreme conditions. The beacon is robust enough to have been recovered from a tree and a lake.

The team is now getting ready for a third engineering flight from Palestine, Texas, while the main ultra-long-duration balloon flight (ULDB) is scheduled for 2020 in New Zealand. It’s this final mission that will demonstrate the SuperBIT’s capability as a facility-class instrument.

When fully operational, the SuperBIT will study strong and weak gravitational lensing and map out the distribution of dark matter around hundreds of galaxy clusters.

Photos (c) Department of Physics, University of Toronto