The European Space Agency (ESA) today marked a milestone in the Rosetta mission to study comets. After being launched nearly one decade ago the spacecraft is now nearing its main objective, comet 67P/Churyumov-Gerasimenko. In 100 days time, the Rosetta probe will awake and begin the final leg of its journey to the comet. According to the ESA, the spacecraft has been in a “deep-space hibernation” since July 2011.

“We are very excited to have this important milestone in sight, but we will be anxious to assess the health of the spacecraft after Rosetta has spent nearly 10 years in space,” said Fred Jansen, Rosetta mission manager at ESA.

Rosetta is expected to wake up on the morning of January 20, 2014. It will then tune-up its navigation controls, point its antenna at Earth, and report its condition to researchers. At that point, the probe will still have around 9 million km (5.6 million miles) to go before reaching its target. It is scheduled to arrive at its destination sometime near the end of May.

Once the Rosetta probe reaches the comet, it will conduct a thorough examination of the object. In addition to thousands of pictures, the mass, shape and coma of the comet will all be examined. The surface of the comet will also be mapped extensively next fall, before Rosetta releases its Philae probe to the object’s surface in November 2014 – the first-ever comet landing attempt. The surface probe will use ice screws and harpoons to secure itself to the comet, then send back images of the surface while drilling into and analyzing the make-up of the comet’s surface.

“For the first time we will be able to analyze a comet over an extended period of time – it is not just a flyby,” said Matt Taylor, a Rosetta project scientist at ESA. “This will give us a unique insight into how a comet ‘works’ and ultimately help us to decipher the role of comets in the formation of the Solar System,”