Radio scientists at Stanford University said they did not detect a signal from the martian spacecraft in data gathered last week. However, they will continue to pore over the information in the hope that a more detailed analysis could show the lost spacecraft has been attempting to contact Earth.

NASA had given up the ghost on the Polar Lander on January 17, more than a month after its December 3 plunge into silence after entering the martian atmosphere.

However, scientists at Stanford announced on January 24 that they might have detected a signal from the lander using the Palo Alto, California universitys 150-foot (45-meter) radio antenna. Those signals seem to have come from Mars on December 18 and January 4.

Engineers subsequently sent new commands to the lander, instructing it to use its UHF transmitter to contact Earth. If that experiment had worked, Stanford should have heard from the lander last week.

New commands will now be sent the 181 million miles (300 million kilometers) to Mars on Tuesday and Wednesday. This time, more powerful antenna arrays in England, the Netherlands and Italy will be poised to listen for any reply beginning on Friday.

"The international community has shown a real interest in being involved in our search. We appreciate their efforts and I think it shows that Mars is something that captivates everyones imagination," said Richard Cook, the Polar Landers project manager at NASAs Jet Propulsion Laboratory.

The odds are extremely slim that NASA will ever hear from the Polar Lander, the second martian mission to go awry in 1999 for the American space agency.

The Mars Climate Orbiter was destroyed in September after a mix-up between English and metric units sent it too close to the Red Planet as it entered orbit.