Scientists have been unable to pick up a signal from the British-built spacecraft Beagle 2 telling them it has landed safely on Mars.
They were waiting for a second contact opportunity later on Christmas Day, hopeful that the first fully European mission to be sent to any planet was still on track.
Scientists said that the silence from space did not necessarily mean the
But by 6.15 a.m. the rocket had passed out of the potential signal range without hearing anything from the 34 kg (75 lb) probe. "We're disappointed, but it's not the end of the world," said mission head Mr Colin Pillinger.
"We're not down-hearted yet," he told reporters at mission headquarters in London, decorated with Christmas lights and tinsel for a party which never happened.
Beagle 2 probe had gone the way of so many other Mars missions before it - and crashed. 2, no bigger than an open umbrella, was due to land on Mars in the early hours Christmas Eve, and scientists had hoped a mission rocket orbiting the planet would pick up a tune signalling a safe arrival.