Phobus-Grunt probe to fall to earth “within hours”

A Russian probe designed to travel to a moon of Mars but stuck in Earth orbit will come crashing down within hours, News. com.au reported, citing the Russian space agency.

Roscosmos has called off all predictions of the likely crash site of its ill-fated Mars probe hours before the spacecraft is due to begin its fatal descent.
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"The operations support group is keeping continuous watch of the Phobos-Grunt spacecraft's descent from orbit," the brief Roscosmos statement said.

It could crash anywhere along the route of its next few orbits, which would include Europe, southeast Asia, Australia and South America.

A large part of each orbit is over water, and scientists have estimated that the risks of the probe crashing into any populated areas are minimal.

The ITAR-TASS news agency cited space agency sources as saying the fiery plunge was now likely to begin at 0540 AEDT and possibly see the debris scatter over a remote spot in the Chinese portion of the Gobi Desert.

The unmanned $US165 million ($160 million) vessel - stuck in a low Earth orbit since its November 9 launch - will be one of the largest objects to re-enter the atmosphere since Russia brought down the Soviet-era Mir space station in 2001.

Sky-gazers report the gold-coloured vessel emitting a bright orange glow as it traverses the globe in an eastward direction between London to the north and New Zealand to the south.

The Soviet-designed system is loaded with 11,000 tonnes of toxic fuel - enough to take it to the mysterious Mars moon Phobos - and a Chinese satellite it had been due to put in orbit around the Red Planet under a landmark deal with Beijing.

Both Roscosmos and US space officials at NASA have made great efforts to downplay the dangers posed by the crashing craft.

Roscosmos predicts that only 20 or 30 segments weighing no more than 200kg in total will survive the explosive re-entry and actually hit the Earth's surface.

Russian and NASA scientists have also downplayed the risks posed by the fuel because it is stored in tanks of light aluminum - not the sturdy titanium used by the now-retired US space shuttle - with a relatively low melting point.

"The explosion of such a vast amount of fuel will completely destroy the station," Russian Academy of Sciences expert Igor Marinin was quoted as telling NTV television.

"But you will get pretty fireworks," he said.

Russia lost sight of the probe almost immediately after its launch and then spent weeks trying to send commands that would either nudge it on its way to Mars or at least enable its controlled return to Earth.

Neither proved successful and Roscosmos now admits that the impact location will depend on varying circumstances such as atmospheric density and even solar activity.