A European Space Agency probe may have crashed on Mars because the craft’s electronic brain thought it was on the ground when it was still more than a mile up, investigators believe.
The Schiaparelli lander is believed to have plummeted from a height of 1.2 to 2.5 miles (2-4km).
Satellite images confirm the spacecraft was probably travelling at more than 186mph (300km/hr) when it smashed into an equatorial Martian plain on 19 October. The probe may have exploded on impact because its fuel tanks were almost full.
Data received from Schiaparelli before the signal was cut off indicates that a computer glitch being the most probable cause of the failure.
After a flawless start to its descent, the craft’s landing sequence appears to have gone out of kilter. The ExoMars 2016 lander ejected its parachute too early and its three clusters of retrorockets fired for about three seconds before switching off.
The thrusters should have burned for 29 seconds, causing the probe to hover briefly over the landing site before descending gently.
Investigators believe the retrorockets cut off so soon because Schiaparelli, which was designed to think for itself during the descent and landing, mistakenly believed it was safely grounded.
Jorge Vago, a scientist on the project, told Nature.com: “My guess is that at that point we were still too high. The most likely scenario is that, from then, we just dropped to the surface.”
Understanding the cause of the crash is vital to the future of ExoMars, an ambitious two-part mission searching for signs of life on the planet.
The primary function of Schiaparelli was to test the automated Russian-designed landing system that will transport a much larger six-wheeled vehicle on to the planet in 2021.
The ExoMars rover, developed in the UK, will drill two metres into the Martian surface and analyse samples for signs of past or present life.
Schiaparelli was carried to Mars by another ExoMars spacecraft, Trace Gas Orbiter.
The orbiter is circling the planet and will check the atmosphere next year for trace gases such as methane, which could have a biological origin.
A meeting will be held in Switzerland in December where the European Space Agency will ask member states, including the UK, for additional funding for the project. The second part of the mission, to be launched in 2020, needs a further €300m (£268m).
The space agency said lessons would be learned from the Schiaparelli crash.