ESA assesses ExoMars parachute tears

The ExoMars 2020 parachute deploy sequence. During recent tests, the two main chutes have suffered tears in their canopies prior to full inflation. Image: ESA

With launch less than one year away, engineers with ESA’s ExoMars programme are struggling to understand and correct problems with the lander’s four-parachute braking system.

Last year, the lander’s huge 35-metre-wide main parachute deployed and performed as expected during a low-altitude drop test from a helicopter at the Swedish Space Corporation Esrange site. But during a subsequent test of all four parachutes on 28 May, from an altitude of 29 kilometres (18 miles), the two main canopies suffered radial tears during the deployment sequence.

Engineers implemented corrective measures and conducted another high-altitude test of the 35-metre parachute on 5 August. Again, the deploy sequence executed normally, but the parachute suffered damage prior to inflation. As a result, the test module descended under a pilot chute alone.

“It is disappointing that the precautionary design adaptations introduced following the anomalies of the last test have not helped us to pass the second test successfully,” said Francois Spoto, ESA’s ExoMars Team Leader. “But as always, we remain focused and are working to understand and correct the flaw in order to launch next year.”

During a low-altitude drop test last year, the second stage main parachute deployed normally. But problems were experienced during two subsequent high-altitude tests. Image: ESA

The ExoMars 2020 mission consists of the European-built Rosalind Franklin rover and the Russian-built Kazachok landing platform. Launch atop a Russian Proton rocket at the Baikonur Cosmodrome is targeted between 25 July and 13 August 2020, setting up a landing on Mars in March 2021. Once safely down, the rover is expected to drive several kilometres, drilling into the soil, collecting samples and chemically analysing them for signs of organic activity. The lander will monitor the local environment.

Using a state-of-the-art heat shield to protect it from the heat of atmospheric entry, the lander requires two parachutes, each one pulled free in sequential fashion by its own pilot chute, to slow the the spacecraft sufficiently in the thin martian atmosphere for braking rockets to take over for the final descent to the surface.

The first stage main parachute measures 15 metres (49 feet) across while the second stage chute, the largest ever used in a Mars mission, measures 35 metres (115 feet) across. For scale, ESA graphics show the second stage chute and its rigging stretching the height of London’s 96-metre-tall (315 feet) Big Ben tower when fully deployed.

Engineers are confident they will be able to identify the root cause of the canopy tears and design a fix. Another high-altitude test of the first stage main parachute is planned by the end of the year with a second attempt to qualify the second stage chute in early 2020.

“Getting to Mars and in particular landing on Mars is very difficult,” said Spoto. “We are committed to flying a system that will safely deliver our payload to the surface of the Mars in order to conduct its unique science mission.”