Nasa's Opportunity rover may be dead on Mars, engineers fear.
The little robot has been travelling over the planet for the last 15 years, but has lost contact with its team on Earth. They fear that the rover might never wake back up, and its mission could come to an end.
Opportunity ran into problems in recent days when a Martian storm that is covering a quarter of the planet swept over the rover. That blotted out the Sun's light, leaving it unable to charge its batteries.
As a result, it has now gone into a shutdown mode where all of its systems are now offline. The only thing still receiving power is an emergency mission clock on board the rover, which wakes it up regularly so that it can check its power levels.
If the rover doesn't find enough energy in its batteries, the systems will shut back down again – and if they stay off, the batteries powering the rover could freeze and shut it down forever. Engineers don't expect it the storm to clear and the batteries to charge for at least the next few days.
Because of the limited power to those systems, engineers can only check intermittently what Opportunity's status is. They have not heard back yet – suggesting the rover has entered its emergency mode – but will hope to hear next time the robot checks in.
The storm is one of the most intense ever seen. It could last up to a month – and scientist might not know whether the rover has made it through until it comes to an end.
If the rover isn't able to charge back up again, it may lose contact with Earth entirely and be declared lost.
That would bring an end to a 15-year mission that gave scientists an unprecedented look at the Martian service.
The rover has already defied expectations: it was initially scheduled for a 90-day mission, though Nasa's projects often run much longer than expected. And it has survived such a storm before, undergoing a much bigger storm in 2007, which knocked out the rover's power and left it without a connection for several days.