Schiaparelli spacecraft crash landed on Mars due to excessive spinning, ESA says
Europe’s Schiaparelli spacecraft, which failed to land on Mars last year, was sent into an unexpected spinning descent which eventually led to its crash, according to the European Space Agency (ESA).
Although it came very close to a successful landing on the planet in October last year, engineers failed to realise how jarring the probe’s parachute descent could be, dooming the touchdown.
Scientists said three minutes after entering the Martian atmosphere, “unexpected high rotation” resulted in the “saturation” of an instrument in the craft tracking spin rate.
The unexpected input to the Inertial Measurement Unit - exceeding the programmed measurement range - had a knock-on effect that caused a major altitude error in the guidance, navigation and control system software.
Schiaparelli’s computer finally decided it was below ground level when in reality the probe was still two miles up in the air.
This led to the craft releasing its parachute and back shell early and firing its landing thrusters for only three seconds instead of 30.
The crash left a visible crater that was later photographed by NASA’s Mars Reconnaissance Orbiter.
Schiaparelli flew to Mars with the Trace Gas Orbiter, which is studying gases in the planet’s atmosphere from orbit.
“The software behaved the way it was supposed to,” David Parker, ESA head of robotic exploration said in an interview.
“It should have been anticipated that the [spacecraft] rotation could reach the maximum. The software could have been more robust had it been more cleverly designed.”
Miscommunication between contractors Thales Alenia Space and Honeywell contributed to the problem, Parker said, adding that ESA took full responsibility.
The agency will apply the lessons learned for the follow-on ExoMars rover life-detection mission, scheduled to launch in 2020.
Schiaparelli’s primary function was to test the combined parachute and retro-rocket landing system designed for the rover.
Contributing to Schiaparelli’s botched landing was the lack of a backup avionics system, a decision made to save money and meet a March 2016 launch date, the report said.
“Schiaparelli... was very close to land(ing) successfully on Mars at the planned location,” it reads.
The accident investigation team’s recommendations include asking NASA, which has successfully landed spacecraft on Mars seven times, to validate the computer models being used to plan the ExoMars rover’s entry and descent to the planet’s surface in 2021.