Satellite russo con carburante tossico potrebbe cadere sull'Australia

Toxic space invader: Failed Mars probe Phobos-Grunt could crash land in Australia

A FAILED Russian Mars probe laden with toxic fuel could crash land in Australia when it falls back down to Earth in the next three weeks.

Scientists are hoping the planet's atmosphere will do its job and incinerate the trouble-plagued Phobos-Grunt, currently hurtling around the Earth at 30,000km/h.

Six tonnes of the 8.5 tonne spacecraft is made up of a poisonous propellant consisting of unsymmetrical dimethylhydrazine (UDMH) and dinitrogen tetroxide (DTO).

James Oberg, a NASA veteran who now works as a space consultant, said the tonnes of toxic fuel could make the Phobos, which has suffered total battery failure, "the most toxic falling satellite ever" when it re-enters the atmosphere between January 6 and January 9.

The Mars probe has been plagued by problems since it blasted off from the Russian-leased Baikonur cosmodrome in Kazakhstan on November 9.

It was designed to land on Phobos, one of two moons circling Mars, and gather rock and soil samples before returning to Earth in 2014.

But when Russia's space agency Roscosmos tried to fire its rockets for a second time to send it on the second stage of its journey, nothing happened.

Phobos-Grunt is moving around Earth at an altitude between 201km and 275km, meaning it will fall anywhere between latitude 51 degrees north and latitude 51 degrees south, which encompasses all of Australia.

But Australia's Spaceinfo.com.au editor Jonathan Nally believed the propellants would burn up entirely as the probe fell through Earth's atmosphere.

"These chemicals are just lethal, very nasty, but we should be safe from them because of the incredible heat of re-entry. After all, this stuff is meant to burn and this probe doesn't have heat shields," he said.

"They still don't know if it was a hardware failure or a software failure."

The plotted landing zone is as accurate as scientists can be - until the final few days and hours before the probe falls from orbit.

"Tracking stations can locate satellites which send and receive signals," Mr Nally said. "But Phobos can't do that, so they must rely on specialist radar stations. And they have very limited coverage, so there will be gaps in where we might know it is.

"Also, we know surprisingly little about the Earth's upper atmosphere. It can even be changed by hot days and puffs up higher into space, and the air within that upper atmosphere causes friction that slows the probe's speed.

"There are a lot of unknown variables when it comes to satellites and space craft coming down.

"It's orbiting at 30,000km/h, that's travelling 10,000km every 20 minutes, so if someone's calculations are out by just 20 minutes that means where they predict the probe will fall could be 10,000km out."

Roscosmos space agency said it expected only about 200kg of the craft to survive re-entry. Mr Nally said that with more than 70 per cent of the Earth's surface covered by water, it was likely any fragments would hit ocean.

Source: http://www.news.com.au