Last October, the Mars probe Schiaparell, sent by the European Space Agency's ExoMars mission, crashed during landing. Since then, the agency has begun investigating the cause of the accident, and now an independent report has finally confirmed that the software problem is the culprit. In addition, the report also put forward some suggestions for the ExoMars task in 2020.
The report points to an unexpected change in the rotational speed of the landing demonstration module (Entry, Demonstrator, Module) between entering the Martian atmosphere and opening the parachute. Although the parachute was scheduled to be turned on, the inertial measurement unit (Inertial, Measurement, Unit) detected a much higher pitch rate than expected, resulting in an out of saturation (saturation) alarm. However, the Guidance Navigation and (Control) system still considers the pitch rate to be consistent with the saturation threshold, so that the detector is separated from the original calculation height. This means that the lander's landing system thought the probe was close to the ground, so it opened the parachute early and launched the System Control (Reaction) in a matter of seconds. However, after the thrust system was closed, the probe was still 2 miles from the ground, and at last Schiaparell had to complete the landing in a free fall". It is reported that the entire free fall takes about 34 seconds.
The report concludes that the reason is insufficient, the cause of the accident parachute modeling of alarm and fault detection, isolation and recovery of misconduct, the design strength and the shortage of subcontractors, the management of the hardware is improper.
Although the Schiaparelli has been destroyed, this mission is not a total failure. In fact, the probe is a test designed by ESA for the next phase of ExoMars. The next phase of the mission is scheduled to begin in 2020, when a Trace Gas Orbiter will enter the orbit of Mars and launch scientific research on the Martian atmosphere.