24 May 2017
The inquiry into the crash-landing of the ExoMars Schiaparelli module has concluded that conflicting information in the onboard computer caused the descent sequence to end prematurely.
The Schiaparelli entry, descent and landing demonstrator module separated from its mothership, the Trace Gas Orbiter, as planned on 16 October last year, and coasted towards Mars for three days.
Much of the six-minute descent on 19 October went as expected: the module entered the atmosphere correctly, with the heatshield protecting it at supersonic speeds. Sensors on the front and back shields collected useful scientific and engineering data on the atmosphere and heatshield.
Telemetry from Schiaparelli was relayed to the main craft, which was entering orbit around the Red Planet at the same time – the first time this had been achieved in Mars exploration. This realtime transmission proved invaluable in reconstructing the unfolding chain of events.
At the same time as the orbiter recorded Schiaparelli’s transmissions, ESA’s Mars Express orbiter also monitored the lander’s carrier signal, as did the Giant Metrewave Radio Telescope in India.
In the days and weeks afterwards, NASA’s Mars Reconnaissance Orbiter took a number of images identifying the module, the front shield, and the parachute still connected with the backshield, on Mars, very close to the targeted landing site.
The images suggested that these pieces of hardware had separated from the module as expected, although the arrival of Schiaparelli had clearly been at a high speed, with debris strewn around the impact site.
The independent external inquiry, chaired by ESA’s Inspector General, has now been completed.
It identifies the circumstances and the root causes, and makes general recommendations to avoid such defects and weaknesses in the future.