On 8 June, mission controllers at ESA will switch ESA's Rosetta comet-hunter into deep-space hibernation for 31 months. During this loneliest leg of its decade-long mission, Rosetta will loop ever closer toward comet 67-P, soaring to almost 1000 million km from Earth.

Marking one of the most dramatic and distant stages of the probe's 10-year journey to rendezvous with Comet 67-P/Churyumov-Gerasimenko, ground controllers at ESOC, ESA's European Space Operations Centre, plan to issue the final command next week to switch Rosetta into hibernation mode.

This will trigger the last steps in the shut-down of the spacecraft, turning off almost all flight control systems including telecommunications and attitude control. Rosetta's scientific instruments were already individually powered down during the first four months of this year. 

"Rosetta is getting farther from the Sun, and soon there simply isn't going to be enough sunlight to power its systems," says Paolo Ferri, Head of ESOC's Solar and Planetary Mission Operations Division."We already achieved a record in July 2010 when we reached 400 million km from the Sun and became the most distant spacecraft ever to operate on solar power alone. Rosetta will double the record distance during the hibernation period."

Rosetta was turned on, to study asteroid Lutetia in july 2010. Since then ERSA has downloadet data, uploadet new software patches and checked systems

At precisely 10:00 GMT on 20 January 2014, the timer will wake the spacecraft, which, seven hours later, will transmit a check signal to let mission controllers know that the spacecraft has woken.

"We've planned for hibernation for some time, and it's a complex phase of the mission," says Andrea Accomazzo, Spacecraft Operations Manager at ESOC. 
"Still, for the flight control team, it's an emotional moment. We're essentially turning the spacecraft off. We're already looking forward to January 2014 when it wakes up and we get our spacecraft back."

Source: ESA