Nasa is about to announce the future of the Opportunity rover, a pioneering robot that has spent years exploring the Martian surface.
The space agency hasn't heard from its rover for eight months, when it disappeared and has not been heard from since.
Now Nasa will send its last messages to the rover. But more than 1,000 have already been sent, with no reply from the rover, which is now facing a cold winter that will almost certainly kill it off if it doesn't manage to wake up.
It's just as hard to say goodbye to Opportunity, as it was to its fellow rover Spirit, project manager John Callas told The Associated Press.
"It's just like a loved one who's gone missing, and you keep holding out hope that they will show up and that they're healthy," he said. "But each passing day that diminishes, and at some point you have to say 'enough' and move on with your life."
The space agency said it would host a media event on "the status of its Mars Exploration Rover (MER) Opportunity". "The briefing will follow NASA’s last planned attempts to communicate with Opportunity late Tuesday evening," Nasa said, asking the world to tune in on Wednesday evening.
The event will be attended by a whole host of Nasa staff, including boss Jim Bridenstine. Many of the engineers and scientists who have led the project will also appear.
Though the all-important message has already been sent, Nasa doesn't yet know whether the final attempts to contact the rover have been successful, and will not until shortly before the announcement.
But there is plenty of reason to be pessimistic. Opportunity has been out of touch since June last year, when it disappeared in a dust storm that blanketed the entirety of Mars, and it's final messages suggested that it could shut down.
If Nasa does fail to hear back this time, the challenges that Opportunity is about to face will mean it is dead. The winds that Nasa had hoped would blow the dust off the rover is now dying down, and being replaced by a cold winter that will probably destroy the components on board Nasa's lander.
Nasa's Opportunity landed in 2004 alongside another robot geologist, named Spirit, making up the Mars Exploration Rover mission. Both were expected to last only a matter of months, and Spirit died in 2010 – but Opportunity has chugged on, travelling the furthest any human-made object ever has on another world.