In June 2018, a huge dust storm clogged the Martian atmosphere, preventing sunlight from reaching the surface. Opportunity, a solar-powered rover, could not recharge his batteries in the dark and went into a deep sleep.

Engineers at NASA's Jet Propulsion Laboratory made more than 1,000 attempts to create opportunities. The rover did not react, even as the storm passed in September. The team withstood a windy season in January, which could erase any dust on the rover's solar panels. They missed options. The engineers sent out a last batch of orders to Opportunity on Tuesday night – one last chance – and received only silence in return.

During his years on Mars, Opportunity has grown to a fraction of a mile at the hour. A robotic arm burrows into the surface, exposing fresh rock and collecting soil samples in its mechanical stomach for analysis. The scientists back on Earth were thrilled when Opportunity sent them detailed pictures of the landscape, and when the motorcyclist found evidence that Mars once had water, enough to support microbial life.

The engineers sent the orders, telling the rover where to drive and what to inspect, but it sometimes seemed like Opportunity was doing the job alone. The communication of the mobile with the direction of the mission resembled less a transmission of data by a robot without intelligence than a despatch of a curious explorer.

The end of Opportunity leaves only one moving mobile on Mars: Curiosity. Curiosity arrived on the planet in 2012 and, despite some technical problems, last year, she is in good health. The rover is on the other side of the planet and, with Opportunity closed, "we have practically lost our surface presence on half of Mars," said Mike Seibert, former director of Opportunity flights. (Seibert was present during the last dust storm on Mars in 2007, at which the vehicle survived very well.)

Curiosity does not have the time or the speed to find his friend. NASA's only perspective on Opportunity comes from robotic spacecraft in orbit around Mars, like satellites surrounding the Earth. From there, Opportunity is a fuzzy blur over a vast rugged landscape.

For engineers and scientists, the pain of the disappearance of the mission is mitigated by this fact: the opportunity was supposed to disappear years ago. Opportunity is one of two rovers that NASA landed on Mars in 2004. The other, named Spirit, landed on the other side of the planet. The missions were to last three months, but they lasted for years.

Spirit reached its end in 2009. During exploration, the rover pierced part of the crust and slipped into a sandbox. The engineers ordered the rover to move his wheels, but this one was stuck. For the first time in his mission, Spirit could not drive on a north-facing slope. Rovers have searched for these slopes each winter, where their solar panels could absorb as much sun as possible each day. "We saw it coming," said Steve Squyres, the lead investigator of both rovers. "From the first day, I knew that if Spirit were to spend a winter on flat ground, it was his last winter."