Бортовые софтверщики (итальянцы, КЯП) загубили еще один аппарат - этот марсианский зонд Schiaparelli
Похоже, переполнение аккумулятора
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.
http://exploration.esa.int/mars/58590-schiaparelli-landing-investigation-makes-progress/