An artist's impression shows the Rosetta orbiter deploying
the Philae lander to comet 67P/Churyumov-Gerasimenko. The
image is not to scale; the Rosetta spacecraft measures 32m
across including the solar arrays, while the comet nucleus
is thought to be about 4km wide. REUTERS/European Space
Agency-C. Carreau/ATG medialab
Comet-chasing spacecraft Rosetta has woken from nearly
three years of hibernation to complete a decade-long deep space
mission that scientists hope will help unlock some of the
secrets of the solar system.
Rosetta, which was launched by the European Space Agency
(ESA) in 2004, is due to rendezvous with comet
67P/Churyumov-Gerasimenko and land a probe on it this year in
an unprecedented manoeuvre.
Scientists hope data the probe gathers will allow them to
peek into a kind of astronomical time capsule that has
preserved for millions of years clues as to what the world
looked like when our solar system was born.
"Since comets are so primitive, they can give scientists a
chance to understand how the solar system formed, where it
came from," Rosetta spacecraft operations manager Andrea
Accomazzo told Reuters ahead of the wake-up call.
On its way to the comet, a roughly 3 by 5 km-large rock
discovered in 1969, Rosetta has been circling the sun on a
widening spiral course, swinging past Earth and Mars to pick
up speed and adjust its trajectory.
The mission will perform several historical firsts, including
the first time a spacecraft orbits a comet rather than just
whizzing by it to snap some fly-by pictures, and the first
time a probe has landed on a comet's nucleus.
Rosetta is also the first mission to venture beyond the main
asteroid belt relying solely on solar cells for power
generation, which is also why it had to be put into a deep
sleep for 957 days.
"It has been so far away from the sun that the solar rays
were not able to generate enough energy to safely operate the
spacecraft," said Accomazzo, who has been working on the
Rosetta mission since 1997.
Accomazzo is based at the ESA's satellite operations in the
German town of Darmstadt, south of Frankfurt.
Having neared the sun again as it tracks the comet on its
elliptical orbit around the sun, Rosetta was gently awakened
by its internal alarm clock at 1000 GMT on Monday. It then
warmed up its systems and transmitted a sign of life - a
radio signal - to its creators on Earth.
Once it is fully up and running, it will start to approach
the comet. By August, it should catch up with it and land its
probe on it in November.
Until the end of 2015, the probe will gather data on the
comet's surface and examine how it changes as its nears the