The launch window to send Russia's Phobos-Grunt unmanned spacecraft to a Mars moon will close on Monday, an airspace source told RIA Novosti. "The spacecraft has already unfolded its solar panels and is in the so-called "barbeque mode," the source said, speaking about the passive thermal control mode during which the spacecraft rotates slowly around its roll axis to prevent one side from continuous solar exposure and overheating.

"So, the ballistic window for Phobos-Grunt's flight to Mars is limited by November 21," he said.

The Mars probe was launched from the Baikonur Space Center in Kazakhstan on Wednesday. The Zenit booster put the spacecraft into an initial elliptical based orbit, but the main propulsion unit failed to put it on course for the Red Planet.

The craft, designed to bring back rock and soil samples from the Martian moon Phobos, is currently moving along a so-called support orbit. All attempts to establish contact with the spacecraft have failed so far.

The head of the Russian space agency Roscosmos, Vladimir Popovkin, dismissed media reports about possible reentry risk, saying Phobos-Grunt contains 7.5 metric tons highly toxic hydrazine and nitrogen tetroxide in its aluminum tanks, which are very likely to explode and destroy the probe upon re-entry.

An anonymous airspace source said some parts of the spacecraft may fall on earth, but they pose no danger.

The Russian space agency expects the possible reentry to take place no earlier than January and hopes to establish contact with the spacecraft until then.

A Russian rocket ballistic expert named the United States, China, Africa, Middle East, some European States, Australia, Japan and in Russian Far East or North Caucasus as possible sites where the spacecraft fragments may fall.

Igor Lisov, editor of the industry magazine Cosmonautics News, said if contact with the spacecraft is established after the launch window's closure, it could still be sent to the Moon or even to an asteroid.

However, he said there were almost zero chances to revive the station.

According to Popovkin, the potential loss of the Mars probe would not affect the pace of Russia's space exploration. He said that Only 30 percent of Soviet-Russian launches to Mars were successful, the Americans have had 50 percent success, while all attempts by Japan and Europe have failed so far.

According to NASA, though, Russia has failed all 17 attempts to study the Red Planet since 1960. The most recent failure occurred in 1996, when Russia lost its Mars-96 orbiter during the launch.