Published online 4 November 2011 | Nature | doi:10.1038/news.2011.630

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Mission to Martian moon is the country's first interplanetary attempt since 1996.

Phobos, as seen in 2008 by NASA's Mars Reconnaissance Orbiter. NASA/JPL-Caltech/University of Arizona

For the first time in 15 years, Russia is getting back into the business of interplanetary space science. It plans to launch an ambitious mission on 8 November to return a sample of soil from the Martian moon Phobos.

The Phobos-Grunt mission (which means Phobos-soil) would welcome Russia back to the elite group of nations — the United States, Japan and the European countries — that do science beyond the Moon. China would also join the club, as embedded in the spacecraft is a small Chinese satellite, Yinghuo-1, that will separate from Phobos-Grunt to orbit and observe Mars.

Success could pave the way for Russia to pursue more ambitious missions based on similar designs — missions have been proposed to Mercury, Venus or even Jupiter's moon Europa. "The major outcome is that Russia might establish its credibility again," says Roald Sagdeev, former director of the Space Research Institute (IKI) in Moscow, which has developed most of the 20 science instruments on the payload. "It would open the door for major international missions."

Mars bonus

The mission might provide scientific payback beyond just a detailed study of Phobos, a pocked, irregular asteroid thought to have been captured by Martian gravity. Scientists suspect that the moon is coated in material ejected from Mars, perhaps during a period of heavy bombardment by asteroids 4 billion years ago.

So if Phobos-Grunt does return to Earth with traces of Mars embedded in its cache of a few hundred grams of pebbles and dust, the humble 5-billion-ruble mission (US$163 million) could end up performing basic aspects of a Mars sample-return mission far more cheaply than a three-stage mission envisaged by NASA that would cost $8.5 billion.

Phobos-Grunt is scheduled to launch at 20:16 universal coordinated time (UTC) on 8 November from the Baikonur Cosmodrome in Kazahkstan, according to Alexander Zakharov, the project scientist for the mission at IKI in Moscow. Zakharov says that the entire spacecraft and most of the instruments are new, though the designs draw upon the nation's legacy of three successful Luna missions, which in the 1970s retrieved a few hundred grams of Moon rocks.

Fresh start

Since then, history has not been kind to the Russian space programme. Two missions to Phobos, both launched in 1988, failed shy of their goal (which at the time did not include sample return)1. And in 1996, the Mars 96 mission, which aimed to establish geophysical seismic stations at the surface of Mars, left the launch pad, but never even reached Earth orbit.

Russian space scientists work on the Phobos-Grunt spacecraft as they prepare it for a planned 8 November launch. STR/AFP/Getty Images

Sagdeev, now at the University of Maryland in College Park, says Russia keeps trying to return to Mars and its moons "with the same instinct that brings a criminal back to the scene of the crime". This time, he says, he has more confidence in the launch rocket and the boosters that will get the spacecraft to Phobos, though in his opinion the complicated sample-return operation is quite risky. Zakharov says that with so many risks, each one serially dependent on the step before, he is just concentrating on the launch.

If the mission is successful, the probe will reach Mars in October 2012, and land on Phobos a few months later. The sample-return package could return to Earth by 2014, while other instruments, such as a mass spectrometer, will remain on the lander and stay behind to carry out scientific measurements at the surface of Phobos.

Dusty treasure

But the real payoff would be the sample-return cache. Scientists would want to date a piece of Phobos, thought to be a carbonaceous asteroid from early in the Solar System's history, and see if it contained any organic matter, says Meenakshi Wadhwa, a cosmochemist at Arizona State University in Tempe.

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Dating a piece of ancient Mars crust found on the asteroid would be even more exciting, she says, but it would not satisfy all scientific desires. As with the 56 meteorites that have been traced to Mars, it would be impossible to connect a fragment of Mars found on Phobos to the specific terrain from whence it came. Moreover, it would be nearly impossible for the fragment to contain life, or even a record of it, says Wadwha, because the ancient Mars fragments would most probably be igneous rock — not a place to look for life — and because records of life would probably be destroyed by the impact that brought it to Phobos. The importance of a full-fledged sample return mission from Mars remains, she says: "You want to sample sedimentary rocks on Mars."