The spacecraft is not due to leave the ESTEC Test Centre in Noordwijk, the Netherlands until the end of August. Instead its container became the venue for Hera’s global leak test, confirming the continued integrity of the spacecraft’s propulsion system following its 10-month long environmental test campaign.

The principle is simple, explains Hera mission manager Ian Carnelli: “Hera’s propulsion tanks are loaded up with gaseous helium at 300 bar, or standard atmospheres. Next place the spacecraft inside its container, adding sensors to check if the interior pressure remains the same over the course of the day-long test.

“Hera’s propulsion system has already undergone one leak test at the premises of Avio in Italy, back before the Propulsion Module was integrated with its Core Module. But since then Hera has undergone testing to replicate the stresses of launch and also operations in the vacuum of space, so we need to check no harm was done in the process.”

For safety reasons the leak test took place inside the Test Centre, Large European Acoustic Facility, LEAF, which has already been the venue for the mission’s acoustic testing, reproducing the violent noise of take-off.

Having passed this latest test, Hera and its accompanying CubeSats continue their functional testing, with launch due in early October.