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Alarm clock to wake up slumbering comet-hunter

Sudeshna ChowdhuryThe Christian Science Monitor

It is time for Rosetta to wake up from its deep-space slumber. 

The spacecraft was made to fall asleep in mid-2011 after it cruised far from the Sun and out toward the orbit of Jupiter, according to a press release by the European Space Agency. 

Rosetta was launched in 2004 and is chasing comet 67P/Churyumov–Gerasimenko. A clump of ice, dust, and gas that orbits the sun about every six and a half years.

According to the press release, "the most important alarm clock in the Solar System" will wake up Rosetta, which operates on solar energy. 

But does Rosetta have enough power to carry out the mission?

"I do not see why it won't work," Jim Burch, one of Rosetta spacecraft's principal investigators, told the Monitor. 

While Rosetta was asleep, its power was utilized only to keep the heaters and computers running, but there has to be enough power to turn on the transmitter so that scientists can receive the signals from Earth in order to know that it is awake, he adds. 

Currently, the spacecraft within about 400 million miles of the Sun, which essentially means that Rosetta will continue to get enough solar energy. 

Once mission controllers have confirmed the spacecraft's health, each of its scientific instruments will be switched back on and checked out, stated the press release.

Later on, the spacecraft is expected to make some close flybys, triangular passes where the spacecraft flies past the comet, turns around and again flies back, during which the spacecraft will make some close observations about the comet, says Burch.

So far, the spacecraft has made three flybys of Earth and one of Mars, according to the press release. In May, Rosetta will make a major maneuver to line up its target comet in August, according to the press release. If the mission is successful, it will become the first space mission to attempt a landing on a comet and the first to follow a comet as it swings around the sun.

Around November, says Burch, Rosetta will release a lander – essentially another spacecraft inside the larger spacecraft – whose shock absorbers will touch down on the surface of the comet.

The strategy is to make Rosetta face the sunlit side to get good pictures of the comet, Burch says. From the dawn or dusk side we can learn about the eruptions and emissions released by the comet, and we also want to learn about the magnetic fields and gases emitted by comets, as well as carry out some in situ measurements, he adds. 

The bigger aim, though, is to learn about the comet. "It has been suggested that comets are the source of life and water on earth. So, for us this project will help us learn how life originated on earth and where the water came from," he says.