The chances of rescuing a Russian probe that is stuck in an Earth orbit after failing to set out on its planned mission for Mars are very small, the Interfax news agency reported on Friday.
Mission control failed overnight even to obtain data from the Phobos-Grunt probe, which was launched earlier this week in what Moscow had hoped would be a triumphant return to inter-planetary exploration, it said.
"Overnight, several attempts were made to obtain telemetric information from the probe. They all ended with zero result," Interfax quoted a source in the Russian space sector as saying.
"The probability of saving the probe is very, very small," added the source, who was not identified.
Nonetheless, attempts to make contact with the probe would continue Friday, also using Earth-based facilities operated by NASA and the European Space Agency, the source added.
Russia's space agency have said scientists have a window of only a few days to reprogramme the probe in a bid to send it on its route to Mars. If this does not happen, it risks falling back to Earth.
If the rescue attempts fail, the slowly descending probe could fall early next month, a space industry source told the RIA Novosti news agency, amid varying predictions including for late this month.
"I think the probe will definitely not fall to Earth earlier than December 3," the source said, adding the probe was losing height only gradually.
The mission went awry after launch Wednesday when the five-billion-ruble ($165 million) probe's engine failed to fire, leaving it orbiting the Earth rather than starting its journey towards the red planet.
The probe had the unprecedented mission to land on the Martian moon Phobos and bring a sample of its rock back to Earth.
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