Scientists insisted, though, it was still entirely possible that the tiny lander, Beagle 2, had survived and noted the bigger part of the 260-million-euro (325-million-dollar) mission had been placed right on track.

"I'm afraid it's a bit disappointing but it's not the end of the world," Beagle 2's chief scientist, Colin Pillinger, told the press in London.

"Please don't go away from here believing we've lost the spacecraft."

Just earlier, Beagle's mothership, Mars Express, had been steered into orbit at the end of a 400-million-kilometer (250-million-mile) odyssey lasting more than six months, causing jubilation at the European Space Agency's mission headquarters here.

"We now have an operational Mars mission. This is the most extraordinary Christmas present I've ever head," ESA Director General Jean-Jacques Dordain said.

German Research and Education Minister Edelgard Bulmahn, noting it was the first time ESA had ever sent a solo mission to another planet, declared: "It's a great day for Europe."

Mars Express and Beagle 2 are Europe's champions in a friendly and undeclared joust with the United States to confirm whether water exists on the planet touted by futurists as a potential home for humans.

A fragile marvel packed with hi-tech instruments, Beagle 2 was to have landed near the Martian equator at 0254 GMT at a flat basin called Isidis Planitia and dispatch a radio callsign home, relayed by the US orbiter Mars Odyssey, to say all was well.

But at 0630 GMT, when Mars Odyssey was in position to hand on any message, the ether was agonisingly empty.

"I'm sorry to say there's no signal yet," said ESA's director of science, David Southwood.

"It's not the end of the story... we are sure Beagle is on the surface, we just need to hear from him."

Experts had always sketched the landing as the mission's most daunting challenge, for Mars is notorious for throwing up high winds, fierce dust storms and jagged rocky surfaces to deter earthly invaders.