At 10am GMT on the 20 January 2014, an ‘alarm clock’ went off on board a tiny spaceship, more than 800 million kilometres from Earth. The European Space Agency’s craft Rosetta began restarting its systems after a 31-month ‘deep-space hibernation’, which had brought it out past the orbit of Jupiter and into pole position for its rendezvous with Comet 67P within just a few months.
After warming up its systems and slowing its rotation, Rosetta checked the stars to work out where it was. Then it pointed its antenna towards Earth and phoned home.
That signal took 45 minutes to reach ESA Mission Control in Darmstadt, Germany, where it was greeted with jubilation.
Rosetta’s mission, and the landing of the Philae lander on Comet 67P was one of the great science stories of 2014. Nothing has been heard from Philae since November 15, as the lander is partially in shadow and unable to use its solar panels to charge its batteries. As the comet gets closer to the sun during 2015, it’s hoped that Philae may reawaken.
In the meantime, there is a lot more exciting science to come with Rosetta. As the comet gets closer to the sun, it has been warming up, and the gaseous material which had been frozen below its surface is escaping. This results in the development of the comet’s coma or atmosphere, and its tail.
Rosetta will become the first spacecraft to witness at close quarters the development of a comet’s coma and the subsequent tail streaming for millions of kilometres into space. Rosetta will then have to stay further from the comet to avoid the coma affecting its orbit. – ESA
Comet 67P and Rosetta will reach perihelion, their closest point to the sun, later this year on August 13.
If you haven’t seen it before, you really should check out the Where is Rosetta animation on the ESA website. It provides a fantastic visualisation of the trajectory of the entire Rosetta mission, from its launch in 2004.