It's the digital analog (see what I did there?) for a common science-fiction trope in just about any story that involves travel to deep space -- the characters must enter a long-term hibernation mode to conserve energy and stay alive for a long journey of millions of miles. Next week, the Rosetta spacecraft will awaken after years spent in "sleep mode" on its way to rendezvous with and eventually catch a ride on a comet.
The European Space Agency launched Rosetta all the way back in 2004, with the ultimate goal of chasing down comet 67P/Churyumov-Gerasimenko to study it for two years and eventually land a probe on the surface of the comet itself. Unlike many other deep space craft that run on what's essentially nuclear power, Rosetta is powered by huge solar panels. To conserve energy, most of its systems were put to sleep in the middle of 2011 as it made its way toward the orbital path of Jupiter. Only its computers and heaters have remained awake.
On Monday, at 10:00 GMT, Rosetta's on-board "alarm clock" will start a sequence of events at the behest of the craft's internal computers, starting with warming up Rosetta's startrackers, which the ESA says will take around six hours. Next, the thrusters come online, followed by switching on the startrackers and finally Rosetta will be ready to point itself straight at Earth, switch on its transmitter and once again begin communicating with the European Space Operations Centre. I imagine the initial exchange, when translated from binary, is likely to go something like this:
"ESOC, this is Rosetta. I am awake and ready to get back to work. Let's rustle ourselves a comet!"
"Rosetta, this is ESOC. Welcome back. We're going to start a data transfer now to get you up to speed."
"Roger that, ESOC. I see that data coming through. Looks like a lot has happened since 2011. Save a pair of those Google Glass for me. And holy geez! What did you people do to Miley Cyrus?"
After waking up, Rosetta will travel for a few more months before finally making a rendezvous with the comet in May. The lander, Philae, will be delivered to the surface of the comet in November, where its feet will drill into the comet to hitch a ride and conduct several months of study during the journey.
You can get more details on the wake up process in the video below: