- Fourteen ton spacecraft still has 11 tons of toxic rocket fuel on board
- Experts admit they have no idea when and where it will hit
- Mission aimed to retrieve soil samples from Mars moon Phobos
Last updated at 2:36 PM on 14th January 2012
A failed Russian Mars probe, which became stuck in Earth's orbit after its rocket boosters failed to ignite, is expected to plunge back to Earth on Sunday, with experts admitting they have no idea when or where it will hit.
The Phobos-Grunt mission, which was billed as the most exciting Russian space mission in decades, aimed to retrieve soil samples from the Martian moon Phobos.
But to the embarassment of Russain scientists the spacecraft, which has been described as a flying fuel tank, became stuck after a initially successful launch on November 8.
Doomed: The Phobos-Grunt probe blasts off successfully in November last year. It is expected to come crashing back to earth on Sunday after its booster rockets failed to ignite and send it on its way to Mars
Since then it has slowly been losing altitude due to gravity's pull.
Worryingly the 14-ton spacecraft still has an estimated 11 tons of highly toxic rocket fuel on board namely DiMethylHydrazine and Dinitrogen TetrOxide.
It is expected to re-enter the atmosphere above Argentina Sunday or Monday, the Russian space agency Roscosmos said in a statement on Friday.
Mission controllers remain confident that most of the craft will disintegrate as it re-enters the earth's atmosphere and the fuel is housed inside aluminum tanks which have a relatively low melting temperature.
Re-entry: The probe burns red hot as it approaches earth's atmosphere in this image captured by the German Tracking and Imaging Radar facility
Igor Lissov, an independent Moscow-based space observer said: 'The fuel indeed poses lethal danger in case of close contact, but I haven’t heard of a single case of any civilians poisoned by rocket fuel from all the derelict satellites and failed rockets throughout the space era.
'The objective reality is that it burns on re-entry. There is no reason to panic.'
Some experts believe that the fuel could have frozen and therefore survive the fiery descent, posing a strong threat if it spills over populated areas.
Jonathan McDowell of the Harvard-Smithsonian Centre for Astrophysics in Cambridge, Massachusetts, said that the probability is low that a large lump of toxic fuel will prove hazardous.
He noted that some of the probe’s equipment is dense and could survive re-entry, but added the odds are that any surviving pieces will end up in the ocean.
He said: 'All the best rules in the world put in place to prevent uncontrolled satellites from crashing down do little if any good in the event of a launch failure.
'This is always going to be the risk that something breaks, and you end up with a situation like this. You can minimize it, but you can’t prevent it entirely.'
Due to constant changes in Earth's upper atmosphere, which is strongly influenced by solar activity, the exact time and place of the satellite's return is unknown.
Predictions on Friday had the satellite re-entering over the Atlantic Ocean, east of Argentina, around 3:22 p.m. EST.
'The technology is such that there is no way we can control or predict where Phobos-Grunt will come down,' said Michael Simpson, executive director of the Colorado-based Secure World Foundation.
'With 73 percent of the planet covered in water, odds are this thing is going to splash down rather than hit land,' he said. 'The chance that this is going to be a threat to anyone is extremely remote, but people are concerned.'
Flying fuel tank: The failed probe still has 11 tons of highly-toxic fuel on board
They predict that only between 20 and 30 fragments of the Phobos probe with a total weight of up to 200 kilograms will survive the re-entry.
In 2008, the U.S. Navy shot down a stranded U.S. spy satellite reportedly to cut the contamination risk of 100 pounds (45 kg) of rocket fuel. That satellite's tank, however, was believed to have been made of metal alloys more resistant to heating than aluminum, Simpson said.
Crashdown: A Handout image released by the Russian Federal Space Agency Roscosmos maps the huge area where controllers say the Phobos-Grunt will fall
One component of Phobos-Grunt that likely will survive re-entry is a small return capsule specifically designed to make a crash landing back to Earth in 2014.
Phobus-Grunt's return to Earth is being monitored by dozens of organizations, including the Inter-Agency Space Debris Coordinating Committee, an offshoot of the United Nations' Committee on the Peaceful Uses of Outer Space. The panel includes representatives from 12 space agencies, including NASA, Russia and China.
Botched: The ambitious mission was meant to re-install pride in the Russian space agency
The spacecraft is the third large satellite to return to Earth since September, when NASA's defunct Upper Atmosphere Research Satellite fell out of orbit, showering debris into the Pacific Ocean. Germany's Rosat X-ray telescope re-entered a month later over the Bay of Bengal.
The $170-million Phobos-Ground mission was Russia’s most expensive and the most ambitious space endeavor since Soviet times.
Destination Mars: The Phobos-Grunt probe being prepared for launch in November this year
The spacecraft was intended to land on the crater-dented, potato-shaped Martian moon, collect soil samples and fly them back to Earth, giving scientists precious materials that could shed more light on the genesis of the solar system.
The probe was successfully launched on November 9 and entered a preliminary orbit where its engines were supposed to fire to set it on its path to Mars.
They never did, and attempts to fix the glitch by Russian and European Space Agency experts failed.
Russia’s space chief has acknowledged the Phobos-Ground mission was ill-prepared and risks of its failure were high, but said that Roscosmos had to give it the go-ahead so as not to miss the limited Earth-to-Mars launch window.
Phobos-Ground marked Russia’s first planned foray beyond Earth’s orbit since a botched 1996 robotic mission to Mars.
That probe, designed by the same Lavochkin company, crashed shortly after launch due to an engine failure. The firm also built two other Phobos-bound probes that failed in 1988.
The crash of Mars-96 generated strong international fears because of some 200 grams of plutonium onboard. The craft eventually showered its fragments over the Chile-Bolivia border in the Andes Mountains, and the pieces were never recovered.
MOSCOW WE HAVE A PROBLEM! WHERE THE CRAFT SHOULD HAVE GONE
- Phobos is the larger and closer of the two moons of Mars, the other being Deimos.
- Both moons were discovered in 1877, Phobos named after the Greek god Phobos, a son of Ares (Mars).
- A small, irregular-shaped object, Phobos orbits Mars closer than any other known moon orbits its planet.
- It orbits so close to the planet that it moves around Mars faster than Mars itself rotates. As a result, from the surface of the planet, Phobos would rise in the west, move rapidly across the sky (in a little over four hours) and set in the east.
- Indeed, its orbit is decaying and will eventually smash into the surface of Mars or break up into a Saturn-like planetary ring.
- Phobos is one of the least-reflective bodies in the solar system, and features a large impact crater, Stickney crater.
- Phobos has been photographed in close-up by several spacecraft, whose primary mission has been to photograph Mars.
- The first was Mariner 9 in 1971, followed by Viking 1 in 1977, Mars Global Surveyor in 1998 and 2003, Mars Express in 2004, 2008, and 2010, and Mars Reconnaissance Orbiter in 2007 and 2008.
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