London Europe's first Mars probe remained silent for a third day Saturday, but scientists clung to the hope that the Beagle 2 spacecraft had landed safely on the Red Planet and would respond to a call from its mother ship in about a week.
The British-built Beagle was turned loose by the Mars Express more than a week ago and was scheduled to land on the surface of Mars on Christmas Day and begin searching for signs of life.
But repeated efforts that began Thursday to pick up a signal from the probe, using the powerful radio telescope at Jodrell Bank Observatory in England and NASA's orbiting Mars Odyssey, have failed.
Late Saturday, the Jodrell Bank telescope struck out for a third straight day after scanning Mars for two hours. The NASA spacecraft had similar luck earlier in the day.
"There is no sign from Jodrell," said Gill Ormrod, spokeswoman for the British government's physics and astronomy research agency.
Scientists in California joined the search for Beagle II, using a 150-foot dish antenna at Stanford University to listen for transmissions. They didn't find anything.
Although scientists experienced some technical difficulties, Stanford researchers said the dish would have picked up the signal if the Beagle were transmitting properly.
Scientists now hope Mars Express will be able to contact Beagle once it enters its correct orbit Jan. 4.
"We haven't yet played all our cards," David Southwood, the European Space Agency's director of science, said earlier Saturday. "The baby, we believe, is down on the surface and the mother is very anxious to get in touch."
Mars Express was designed to beam back data gathered by Beagle, and chief Beagle scientist Colin Pillinger said its communications were specifically set up to hear the probe's transmissions.
Beagle, shaped like a pocket watch, weighs 143 pounds.