While no signal has been received from the Beagle-2 Mars lander, its mother ship, the Mars Express, is in orbit around the planet to listen for signs of the surface probe.
Since it descended toward the surface of Mars on Christmas Day, scientists have not heard a single transmission from the Beagle-2 unmanned craft.
But that does not mean that the Beagle scientific team has given up hope.
They acknowledge that the probe may have been destroyed upon entry into the atmosphere or upon impact on Mars. But the scientists also say that there are many other scenarios that could explain why Beagle-2 has not been transmitting from the surface.
Possibly it has landed in a deep crater, or its antenna may be pointing in the wrong direction, or its automatic timers may have been re-set, or perhaps there has been a problem with the solar panels that are needed to charge up Beagle-2's batteries.
No one knows for sure. But since December 25, the NASA earth orbiter Odyssey and powerful radio telescopes on earth, including the Jodrell Bank array in Britain, have scanned the skies for the elusive signal.
That will go on for the next few days. The team leader, Professor Colin Pillinger, says he will continue testing and waiting.
The next important date on the Beagle calendar is January 4, when the European Mars Express orbiter is in its final polar orbit, between 300 and 10,000 kilometers above Mars.
The Mars Express will then be in a prime position to carry out more frequent overflights of the Beagle's intended landing site and listen for signals from the surface.
The European Space Agency announced that an important four-minute burn of the Express's main engine had moved the craft toward that important orbital path.
Scientists say that if the Beagle has landed successfully and is operating properly, it is the Express that will be in the best position to pick up its transmissions.