The specific cause TLDR The thing that measures the aircraft ' s rotation malfunctioned for about a second . The incorrect data that it fed into the overall navigation system made the craft think it was at negative altitude so it basically activated the landing sequence . at 3 . 7 km As Schiaparelli descended under its parachute , its radar Doppler altimeter functioned correctly and the measurements were included in the guidance , navigation and control system . However , saturation maximum measurement of the Inertial Measurement Unit IMU had occurred shortly after the parachute deployment . The IMU measures the rotation rates of the vehicle . Its output was generally as predicted except for this event , which persisted for about one second longer than would be expected . When merged into the navigation system , the erroneous information generated an estimated altitude that was negative that is , below ground level . This in turn successively triggered a premature release of the parachute and the backshell , a brief firing of the braking thrusters and finally activation of the onground systems as if Schiaparelli had already landed . In reality , the vehicle was still at an altitude of around 3 . 7 km .