The European Space Agency has confirmed that a parachute for the ExoMars rover mission, scheduled for launch in July, failed in a test over Sweden earlier this month, the project's second parachute accident since May.
The failure during a high-altitude parachute test on 5 August was a setback for the ExoMars team as engineers worked toward a 19-day launch window, which opened on 25 July 2020. It was the second parachute failure that ExoMars engineers experienced before launching tests after a similar accident May 28.
Four parachutes – two pilot chutes and supersonic and subsonic main chutes – will slow the ExoMars lander after entering the Martian atmosphere. The lander will drop the parachutes and detonate rockets to slowly settle on the surface of Mars.
The engineers have made changes to the critical parachute system after the accident on May 28, but the follow-up test is in trouble, the ESA said in a statement Monday. ESA and industry teams conducted both tests at the Esrange Space Center, which is operated by the Swedish Space Corp. is operated in the far north of Sweden.
"The preliminary evaluation shows that the first steps were completed correctly, but the damage to the canopy was observed before inflation, similar to the previous test," ESA said about the test on 5 August. "As a result, the test module sank alone under the pressure of the pilot chute."
During the test on May 28, engineers tested all four parachutes in the ExoMars Landing System after dropping a 29-kilometer test vehicle out of a stratospheric balloon.
During a normal landing sequence, a pilot is to pull out and deploy a 15 meter (49 foot) supersonic main parachute. This is a larger version of the parachute successfully flown with the European Huygens probe on Saturn's moon Titan. As soon as the vehicle slows down below the speed of sound, a second pilot takes out a 35-meter main subsonic parachute, which will be the largest ever to fly on Mars, and another "ring-slot" design uses more drag produce.
In a statement on Monday, ESA stated that the "overall sequence" was completed during the test on May 28 and that all deployment mechanisms worked as intended. Both main caps of the parachute had cracks in their fabric, but the chutes produced a "good level of expected drag," the ESA said.
After making changes to the parachutes and their bags, the ground crews made a second height trial on August 5, focusing only on the larger subsonic main parachute, ESA said. This test also gave an unsatisfactory result.
"It is disappointing that the precautionary design adjustments introduced after the anomalies of the last test did not help us succeed in the second test, but as always, we are focusing on understanding and correcting the error to introduce it next year. Said Francois Spoto, ExoMars team leader of ESA.
According to the ESA, the engineers have restored all the hardware from the test on August 5 for inspections. The teams also analyze video and telemetry from the test to determine what went wrong.
Two more high altitude parachute tests, one for each major parachute, are scheduled for the end of this year and early 2020. These tests must bring good results – and stay close to their current schedules – if the launch of the ExoMars lander is to stay on track in July or August 2020, officials said.
Parachute tests at high altitude are expensive and require prior planning. ESA said the ExoMars team is exploring the possibility of producing additional parachute test models and performing ground-based simulations to "mimic the dynamics of parachute extraction."
ESA also relies on NASA's expertise in the design of Mars parachutes.
The larger of the two main parachutes of the ExoMars mission operated as planned during a low-altitude fall test in Sweden last year.
The 35-meter parachute for the ExoMars mission is manufactured by the Italian company Arescosmo. The British engineering office Vorticity Ltd. is conducting the test campaign in Sweden under the supervision of the French division of Thales Alenia Space, which has overall responsibility for the ExoMars parachute system.
"It's very difficult to get to Mars and land on Mars in particular," Spoto said in a statement. "We are determined to fly a system that safely transports our payload to the Martian surface to carry out its unique scientific mission."
If the ExoMars lander and rover miss the launch window next year, by the end of 2022, the next opportunity will be to leave Earth on a direct flight to Mars. The planetary starter windows of Mars open about every 26 months, when Earth and Mars are in the correct positions in the solar system, to allow a direct triggering.
The ambitious ExoMars program is a partnership between ESA and the Russian Space Agency Roscosmos. The ExoMars program consists of two parts.
Launched in March 2016, the ExoMars Trace Gas Orbiter is currently monitoring the Martian atmosphere with a range of scientific methane research tools and a camera for mapping changes on the planet's surface. The Trace Gas Orbiter took off aboard a Russian proton rocket along with a DropShip named Schiaparelli, which crashed on final descent on the Red Planet.
Like its orbiter precursor, the second ExoMars mission will be launched with a Russian proton booster from the Baikonur Cosmodrome in Kazakhstan. A European-made carrier module will transport the ExoMars lander from Earth to Mars, where a Russian-made descent surface will bring the European ExoMars rover to the surface.
The Russian descent platform will continue to be used as a stationary landing site, on which Kazachok, Russian for "small Cossack", carries out its own scientific measurements. The European rover will drive several kilometers and drill to a depth of 2 meters. Collect core samples for analysis in the on-board laboratory of the mobile robot.
Scientists have never studied material so deep beneath the surface of Mars where biomarkers and organic molecules could survive on life forms that might have inhabited the planet billions of years ago, when it was warmer and wetter.
Italy is making the biggest financial contribution to the ExoMars program. The Italian department of Thales is responsible for all European industrial work. The United Kingdom is ExoMars' second largest lender, and the Airbus Defense and Space plant in Stevenage, north of London, is responsible for building the Rover vehicle itself.
The ExoMars rover is named after Rosalind Franklin, a British chemist and X-ray crystallographer whose work has contributed to the discovery of the twisted double helix shape of a DNA molecule. The Rosalind Franklin vehicle, which is now in final assembly in Stevenage, is the first European Mars rover.
The Rosalind Franklin Rover and the Kazachok lander should start as early as 2018, but the officials postponed the mission for 2020 after both vehicles had development delays.
ESA's ExoMars project scientist Jorge Vago said on July 26 that the Airbus teams in Stevenage are addressing the main structure of the Rosalind Franklin rover with the Analytical Laboratory Drawer, an instrument box, in the supply of rock and soil sampling equipment three scientific instruments are housed together in the container.
The combination of the Rover structure with the instrument housing has been an important milestone in rover assembly, Vago said. The rover drill has also been installed, and the robot's suspension system and six wheels will be added later.
"At the moment, only the locomotion system is missing on the rover," Vago said in a July 26 presentation to the NASA Mars Exploration Program Analysis Group. "Everything else is already assembled."
The Rover is smaller than the NASA rover Curiosity, which is currently exploring Mars, and slightly larger than the Rover Spirit and Opportunity, which landed on the Red Planet in 2004.
In March, the Kazachok landing platform reached a Thales Alenia Space facility in Turin, Italy, from its NPO Lavochkin factory in Russia. Other components of descent modules, such as the launcher's aerodynamic shield and solar modules, came from Russia to Italy in June.
The ExoMars cruise stage on which the lander and the rover are brought to Mars arrived in April in Turin at Thales Alenia Space at its German manufacturer OHB system.
When completed, the Rosalind Franklin Rover will be delivered to an Airbus plant in Toulouse, France, to conduct environmental testing, according to ESA from the United Kingdom.
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