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Those tests were designed to see if the parachutes could be extracted from their containers and deployed in atmospheric conditions similar to those found on Mars.
ExoMars uses two main parachutes, each with a smaller “pilot” parachute used as part of the extraction process. One parachute, 15 meters in diameter, will be deployed while the ExoMars entry vehicle is traveling at supersonic speeds. Once the vehicle slows to subsonic speeds, it releases that parachute and deploys a 35-meter parachute.
One of the tests last month, of a 15-meter parachute made by Airborne Systems, a U.S. company that produced the parachute NASA’s Perseverance Mars rover, went as planned. “We’re very happy to report that the first main parachute performed perfectly: we have a supersonic parachute design that can fly to Mars,” Thierry Blancquaert, ExoMars program team leader, said in an ESA statement.
The second test involved a 35-meter parachute made by Italian company Arescosmo. In that test, the pilot parachute unexpectedly detached during deployment of the larger parachute, causing a tear. Blancquaert said that, despite the tear, the parachute still sufficiently decelerated a mockup of the decent module.
“We have to know why this problem with the drogue happened, but the main parachute decelerated as expected and did its job,” said David Parker, director of human and robotic exploration at ESA, in a July 6 interview. “But we don’t want that to happen again.”
In 2019, a similar series of drop tests revealed problems with the extraction system, tearing the parachutes. Those problems contributed to ESA’s decision in March 2020 to delay the launch of ExoMars, which had been scheduled for July of that year, to the next launch window in September 2022.
With assistance from NASA, ESA has been working to modify the extraction system, conducting ground tests at the Jet Propulsion Laboratory. Those earlier problems, involving friction between the parachute canopy and the bag that contained it, aren’t linked to the latest test anomaly and appear to be resolved, ESA noted in its statement.
Another change has been the addition of the Airborne Systems parachute as a backup to the original European-developed parachute. “That came out of the earlier problems. We thought we needed to put some risk mitigations in place and give ourselves some options,” Parker said.
Another round of parachute drop tests, two of each parachute, is scheduled for late this year in Oregon. A final series of parachute tests will take place next summer, around the time the spacecraft is headed to the Baikonur Cosmodrome for launch on a Proton rocket. “We have some opportunity for confidence tests very late before launch,” he said.
The other technical issue that delayed the ExoMars launch last year, beyond complications caused by the pandemic, involved Russian electronics in the descent module. Parker said those components are being rebuilt in Russia and will be shipped back to Europe for integrated system tests on both a testbed and then on the spacecraft itself.