Sensor failure behind ExoMars landing disaster
Image credit: Rlevente
The failed landing of Europe’s ExoMars Schiaparelli lander was caused by a faulty sensor that made the probe think it was already near the ground while it was still 3.7km above the surface of Mars, the European Space Agency (ESA) has confirmed.
As a result, Schiaparelli ditched its parachute and turned off its retro rockets, which were designed to bring it to a standstill 2m above the planet's surface, too early. Instead of a gentle thud, the probe smashed into the ground at 300km/h, creating a small crater in Martian soil.
According to a report released on Wednesday by ESA, the failed sensor, part of the lander’s navigation system, was gauging altitude by measuring how fast the 2.4m in diameter probe was spinning.
“When merged into the navigation system, the erroneous information generated an estimated altitude that was negative - that is, below ground level,” ESA said. “This in turn successively triggered a premature release of the parachute ... and a brief firing of the braking thrusters.”
The landing attempt, which took place on 19 October this year, was supposed to test landing systems for a much larger rover to be delivered to the Red Planet in 2020. For ESA, the timing of the mishap was rather inconvenient as it is about to ask its member states to provide €300m of additional funding to complete the rover mission.
Schiaparelli was also equipped with technology to measure wind speed on the surface of Mars but its scientific mission was supposed to last only two days.
ESA said that despite the loss of the spacecraft, the mission was a success as it provided a large amount of data that would allow the engineers to fine-tune the landing system for the rover.
“We will have learned much from Schiaparelli,” David Parker, who oversees space exploration programmes for ESA, said in a statement.
Schiaparelli was also only a secondary payload carried to Mars by an orbiter, which has successfully established itself in the orbit around the planet. The Trace Gas Orbiter, fitted with sensor to detect methane in the atmosphere of Mars, has conducted first scientific measurements this week.
The landing system of the ExoMars rover, which is currently being built in the UK, is supposed to have the same guidance and navigation systems as those used on Schiaparelli.