Scientists say there is "almost zero chance" of hearing from the Philae space probe again after it touched down on a comet more than a year ago.
The German Aerospace Centre (DLR) said any response from the lander would be "very surprising". The last communication was on June 9 last year.
"We haven't had contact since last summer but kept on sending communications hoping it would react," Manuela Braun, of the DLR, said.
"So we're saying goodbye without knowing what has happened to it.
"It's now really almost zero (percent chance) that Philae will get back in contact with us."
She added: "This was Plan B, when the lander bounced off and went to a shadier, colder landing site we adjusted everything so it would work."
Before it stopped communicating, Philae sent back reams of data about 67P/Churyumov-Gerasimenko that scientists will spend years analysing.
The unit made an historic landing on the comet in November 2014 after bouncing several times from its surface.
It was launched as part of the European Space Agency's Rosetta mission and was the first robot to be dropped on a comet.
The mother craft, Rosetta, will continue to carry out scientific measurements in orbit until September, when it will be steered to land on the surface as well.