Europe’s Mars lander probably crashed because of a problem with its navigation system

The European Space Agency is still trying to figure out why its ExoMars Schiaparelli lander crashed on the surface of Mars last month, and it’s looking like it has something to do with bad data that the vehicle gathered during its descent. In an update today, the agency said that information collected by one of the lander’s instruments made the vehicle think it was below ground level — while it was still falling. This triggered a chain of events that threw part of Schiaparelli’s landing sequence out of whack and ultimately caused the spacecraft to slam into the ground.

The vehicle thought it was below ground level — while it was still falling

The culprit seems to be an instrument called the Inertial Measurement Unit, which records how fast the vehicle is rotating. Just after Schiaparelli deployed its parachute, the IMU suffered a glitch for just one second, enough to muck up the lander’s navigation system. As a result, the lander thought it had just landed or was about to land, so it deployed its parachute early. The vehicle’s thrusters briefly turned on, too, and the ground-systems were activated — even though Schiaparelli was still 12 feet above the ground.

ESA claims it has reproduced this problem through computer simulations, but we won’t know the full extent of the failure until a report is released early 2017. “This is still a very preliminary conclusion of our technical investigations,” says David Parker, ESA’s director of Human Spaceflight and Robotic Exploration.

A photo of Schiaparelli’s impact site, taken by NASA’s Mars Reconnaissance Orbiter NASA

If true, it does confirm a few suspicions ESA scientists had following the crash. And it’s important to remember that Schiaparelli was just a demonstration lander. It was meant to validate ESA’s method for landing large payloads on the Martian surface, in preparation for the next phase of the ExoMars mission, when the agency will try to land a much larger rover on Mars. ESA claims that lessons learned from the Schiaparelli crash will be used to ensure the ExoMars rover lands intact. “We will have learned much from Schiaparelli that will directly contribute to the second ExoMars mission being developed with our international partners for launch in 2020,” said Parker.

Plus with all the hoopla surrounding Schiaparelli’s crash, it can be easy to forget that the ExoMars mission still experienced a big win in October. After the (crash) landing, the ExoMars Trace Gas Orbiter — which traveled to Mars with Schiaparelli — successfully inserted itself into orbit around the Red Planet. In January, the orbiter is going to spend start adjusting its orbit in order to get closer to the planet. Then later next year, it will start sniffing out molecules in the Martian atmosphere, which may indicate if there are traces of life on the surface below.