It's Time for Comet-Chasing Spacecraft Rosetta to Wake Up

Update 1/20/2014 Rosetta is awake! Phew. The ESA reports they received the signal at 6.18pm GMT, and the spacecraft tweeted "Hello, world!" in many different languages. "This was one alarm clock not to hit snooze on, and after a tense day we are absolutely delighted to have our spacecraft awake and back online," said Rosetta mission manager Fred Jansen in a release. 

It’s an exciting and nerve-wracking day for the European Space Agency, as they wait to see if comet-chasing spacecraft Rosetta has woken up as planned after a 31-month snooze. You can join in the anticipation by following the ESA’s live stream above, and keeping an eye on Rosetta’s own Twitter feed.

still sleeping

— ESA Rosetta Mission (@ESA_Rosetta) December 3, 2013

The spacecraft was scheduled to rise and shine from its deep space hibernation today at 10am GMT (already a few hours ago), but we won’t actually know if it managed to drag itself out of its slumber until much later this afternoon.

That’s because although its pre-programmed internal alarm clock was set for the morning wake-up call, it will only be able to reconnect with the ESA on Earth once its star trackers have warmed up, which is expected to take about six hours. Its signal will then take another 45 minutes to reach Earth. A live blog on the Guardian explains the process:

Once they have warmed sufficiently to work, these small telescopes [the star trackers] will allow onboard software to recognise star patterns. This will tell Rosetta how it is oriented in space, then an onboard ephemeris will allow the spacecraft to turn its antenna towards Earth. Then, the transmitter springs into life and the signal begins its journey.

For now, all the ESA can do is sit tight in the control room in Darmstadt, Germany, and listen out for that signal. And you can imagine it’s pretty tense there right now. They simply don’t know if the wake-up has worked, and for now they’re helpless to do anything but wait. The ESA calls Rosetta’s timer “the most important alarm clock in the Solar System.” The Guardian calls the day’s proceedings “seven hours of terror.”

The spacecraft has been chasing comet 67P/Churyumov–Gerasimenko since 2004, but has been out of contact since it was put to sleep in mid-2011 in order to conserve energy (it runs off solar but the ESA explains it’s ventured far away from the Sun now, towards Jupiter). “Thirty-one months later, Rosetta’s orbit has brought it back to within ‘only’ 673 million kilometres of the Sun, and there is finally enough solar energy to power the spacecraft fully again. It is time to wake up,” the agency says.

Motherboard’s Amy Shira Teitel explains that Rosetta’s adventure will really get going in November, when it will fly within less than a mile of the comet and drop its Philae lander, which should collect a treasure trove of data and images and tell us more about the beginnings of our Solar System.

That’s provided it actually wakes up as planned. As mission manager Fred Jansen told the Independent, “We’re very excited to have this important milestone in sight, but we’ll be anxious to assess the health of the spacecraft after Rosetta has spent nearly 10 years in space.”

We’ll keep you updated when we hear more.