Europe and Russia’s ExoMars lander may have suffered a computer glitch during its descent to Mars last week, ultimately causing it to crash-land into the planet’s surface, Nature reports. As the lander fell, the mysterious software bug may have caused the vehicle to think it was closer to the ground than it actually was, a lead researcher with the European Space Agency suggests. That may be why the whole landing sequence was thrown out of whack.

A software error is ultimately good news for the ExoMars mission

It’s just a hunch, so the true cause of the crash is not yet known. But a software error is ultimately good news for the ExoMars mission — a joint venture between the European Space Agency and Roscosmos to search for signs of life on the Red Planet. The crashed lander, called Schiaparelli, was really just a demonstration spacecraft, meant to show that ESA and Roscosmos have the capability to land heavy objects on Mars. A successful landing would have boosted confidence for the next phase of ExoMars — sending a rover on Mars in 2020. But if a computer problem is to blame for Schiaparelli’s demise, that’s a problem that’s easier to fix before 2020 than a hardware issue.

Fortunately for ESA, it looks like Schiaparelli performed many other aspects of its job beautifully. The lander entered the Mars atmosphere exactly on schedule and deployed its parachute when it was supposed to. But over four and a half minutes into the fall, the lander ejected its heat shield and parachute — over half a minute too early. Then the vehicle’s thrusters, meant to slow down the spacecraft even further, ignited for just three seconds when they were supposed to ignite for 30. Given all these failures — and the new crater that NASA spotted at Schiaparelli’s landing site — it’s pretty likely that the lander slammed into the Martian surface way too fast.

All this seems to suggest a software error, says Andrea Accomazzo, who is in charge of ESA's solar and planetary missions. Accomazzo thinks maybe Schiaparelli had a problem processing all the information it was getting from its sensors. This led the spacecraft to think it was at a lower altitude than it was during the fall, causing many of its landing operations to cut off early.

"If we have a serious technological issue, then it’s different."

The ExoMars rover will be using the same software and sensors as Schiaparelli to land on Mars. So if it does turn out to be a computer glitch, then ESA and Roscosmos can hopefully make the necessary updates before the rover’s launch in four years. "If we have a serious technological issue, then it’s different," Accomazzo tells Nature. "Then we have to re-evaluate carefully. But I don’t expect it to be the case."

The ExoMars team hopes to virtually re-create Schiaparelli’s landing soon to see if they can pinpoint the origin of the failure.