ExoMars plagued by parachutes tearing apart

The mission won’t make its launch date in 2020 if the parachutes fail the next test and if so the entire mission risks cancellation.

The scientists and engineers must have strained their necks as they looked up at the sky over the Swedish Space Corporation Esrange facility that lies above the arctic circle. It was August 5th and the team behind ESAs ExoMars mission was testing the parachute system that is meant to ensure that their Mars rover, Rosalind Franklin, and the Russian surface platform, survives the six minute trip down through the Martian atmosphere and all the way down to the red and rusty surface.

ESA had conducted a similar high-altitude test of the parachute system on May 28th. A stratospheric balloon had carried the system to a height of 29 kilometers and all seemed to work well; the drop test vehicle was released at the planned altitude and the pyrotechnic system functioned correctly. Even the first pilot chute inflated in the way intended.

But as the first main parachute inflated “several radial tears in the fabric were observed immediately following extraction from the main parachute bag, before the parachute experienced maximum load,” ESA writes on their homepage.

The second main parachute shared a similar fate: “[…]one radial tear was observed, again before reaching peak inflation loads.”

First main parachute and second main parachute, what’s up with that? you may ask. Let’s go into that. Here’s an illustration that shows how the system works.

Graphic: ESA

During entry, descent and landing on Mars a lot of speed has to be shed on the way down. First the heatshield and then a series of parachutes help accomplish that. The two main parachutes, the first and the second, require their own small parachute to pull them out of their bag and ensure a correct inflation. The first, main parachute (15 meter diameter ) will be deployed as the spacecraft is still supersonic and it is only needed to bleed of sufficient speed for the next, second main parachute (35 meter diameter) to deploy. The second main parachute is much larger and will let the spacecraft fall downwards at a much slower pace until it reaches the altitude where its onboard descent rockets can take over the rest of the way down.

A grim sight

So I imagine some of the ESA technicians were somewhat anxious for the system to work on August 5th as they tested the system again. They had made hardware inspections and implemented adaptations to the design of the parachutes and the bags that carry them. This time, though, they focused only on the largest parachute, 35 meters in diameter.

It was a grim sight for the ESA folks; again the parachute was torn in a similar fashion as it did during the test on May 28th.

“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, but as always we remain focused and are working to understand and correct the flaw in order to launch next year,” says Francois Spoto, ESA’s ExoMars Team Leader in a press release that ESA has published today.

The press release goes on to say that analysis of hardware, video and telemetry “[…]should reveal the root cause of the anomaly and will be able to guide the way forward in terms of further modifications that might be required to the parachute system before subsequent test opportunities.”

Graphic: ESA

The largest Mars-chutes ever

You might think, how is it ESA can’t get some parachutes to work? Well, to be fair, this parachute system is the largest of its kind that is supposed to fly on Mars. The main chute is 35 meters (115 ft) in diameter and even a small tear will ruin the whole parachute as it moves through the atmosphere at high velocity.

“Nobody has ever done it before with parachutes this big, so technologically this is new territory with all the risks associated,” Nico Dettmann, Head of the Space Transportation Department at ESA, told me over the phone.

Those tests, however, are getting quite close to the July 25th to August 13th launch window of the ExoMars mission – the back-up test for the first main parachute is scheduled before the end of this year, while the next qualification attempt of the second main parachute is anticipated for early 2020.

“If the next tests fail, then we will not make it for the flight to Mars in 2020. These tests are the last back-up and we assume that we can figure out, why the parachutes have failed thus far,” Nico Dettmann says.

“We are hopeful that we can launch in 2020.”

Going forward ESA will team up with NASA to go over the data from the failed tests to see where the parachutes failed and what can be done to fix it. The ESA team will also perform ground-based simulations since there a only few opportunities to do full-scale high-altitude drop tests.

Nico Dettmann, Head of the Space Transportation Department at ESA. Photo: ESA

Mission might get cancelled

If ESA misses the launch, the mission might get canceled altogether.

“The mission would get more expensive and ESAs member states would have to reaffirm their commitment. Right now we concentrate on achieving a successful mission but it is not guaranteed that the mission will survive, if the tests are unsuccesful. 2020 was already the back-up launch date,” Nico Dettmann says.

Mars and Europe don’t have the same good relationship as Mars and NASA when it comes to landers. Although the British Mars lander Beagle 2 successfully landed, it did not phone home afterwards since its solar panels did not unfold correctly, leaving the spacecraft with an insufficient source of power.

The Schiaparelli Entry, Descent and Landing Demonstrator Module- a testbed for the ExoMars rover mission – crashed into the Martian surface in 2016 due to a software glitch. The failed landing was featured in the following video by Scott Manley:

The ExoMars mission is a collaboration between ESA and Roscosmos. ESA is responsible for the Rosalind Franklin rover and the entry system, including the parachutes, while Roscosmos provides the Proton launch vehicle and the descent vehicle that, hopefully, will land ExoMars on a red and rusty surface in 2021.

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