Poorly understood Mars landing conditions led to probe’s demise: report

[May 30, 2017]    By Irene Klotz

CAPE CANAVERAL, Fla. (Reuters) - Europe's Schiaparelli spacecraft came very close to a successful landing on Mars last year, but engineers failed to realize how jarring the probe's parachute descent could be, dooming the touchdown, a report released on Wednesday said.

Schiaparelli flew to Mars with the Trace Gas Orbiter, which is studying gases in the planet’s atmosphere from orbit. The lander crashed during an attempted touchdown on Oct. 19.

Its parachute worked as designed, but atmospheric forces at supersonic speed were not well understood, the report, commissioned by the European Space Agency, said.

"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 the 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.

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," the report said.

However, a powerful spin for a fraction of a second overloaded the spacecraft’s sensors, leading to the false conclusion that it had reached the ground.

As a result, Schiaparelli shed its parachute early, briefly fired its landing thrusters and hit the ground at 336 mph (540 kph). The crash left a visible crater that was later photographed by NASA’s Mars Reconnaissance Orbiter.

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.

(Additional reporting by Maria Sheahan; editing by John Stonestreet)

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