A comet-chasing spacecraft travelling in space for 10 years is set to wake up in late January after 957 days of deep-space hibernation. (Courtesy: AP)
A comet-chasing spacecraft traveling in space for 10 years is set to wake up in late January after 957 days of deep-space hibernation.
Since its launch from Europe's spaceport at Kourou in March 2004, Rosetta, the European Space Agency's spacecraft, has traveled out to a distance of some 800 (m) million kilometers (497 (m) million miles) from the Sun and close to the orbit of Jupiter.
It has passed by Earth three times and Mars once, and flown past two asteroids.
The probe is now closing in on its destination, the enigmatic comet 67P/Churyumov-Gerasimenko, as it begins to move closer to the Sun.
Rosetta was put into deep-space hibernation for the most distant part of its journey.
"It flew almost 10 years in space and in the last two and a half years it was so far from the sun that we couldn't keep it completely active so we had to switch it off," said Dr Paolo Ferri, Head of ESA's Mission Operations Department.
"We have no contact since two and a half years and on Monday we'll have the first signal since then."
Hundreds of millions of kilometers from the Sun, the solar arrays used to power the spacecraft's computer and transmitter could no longer function efficiently.
"We had to spin it up, leave it alone, switch off all the non-essential elements to save power and leave it for two and a half years without any contact and hope that it survived well," Dr Ferri said.
But the time for Rosetta to wake up and prepare for the scientific adventure of the encounter with 67P/ Churyumov-Gerasimenko is now fast approaching.
If all goes according to plan, Rosetta will begin searching for 67P - a lump of rock and ice about four kilometres (2.5 miles) in diameter that is invisible to the naked eye.
The spacecraft's internal alarm clock is set for 1000 GMT on 20 January, and the first signal from the spacecraft is expected no earlier than 1730 GMT.
Rosetta will arrive at 67P in August 2014, where it will become the first spacecraft to orbit the nucleus of a comet and, later in the year, the first to land a probe, Philae, on a comet's surface.
It will also be the first mission to escort a comet as it journeys around the Sun.
Comets are considered to be the primitive building blocks of the Solar System, and likely helped to 'seed' Earth with water, and perhaps even life.
"Over the millennia of the history of earth comets have actually affected our evolution, they probably have affected the evolution of life as well, from the start of life to the destruction of life," Ferri said.
"There are many theories about comets hitting the earth and causing global catastrophes. So understanding comets is also important to see in the future what could be done to defend the earth from comets," said Ferri.
By studying the nature of the comet's dust and gas, Rosetta will help scientists learn more about the role of comets in the evolution of the Solar System.
Rosetta and Philae will keep sending back data until their batteries die or the debris streaming off the comet irreparably damages their sensitive instruments.