After a decade's journey, the ESA's Rosetta spacecraft has finally reached its rendezvous with comet 67P/Churyumov-Gerasimenko. Now, the spacecraft is in orbit around the comet and will follow it for one year as it travels around the sun.
"Thruster burn complete. Rosetta has arrived at comet 67P. We're in orbit!" the ESA announced on Twitter.
But Rosetta's mission has only just begun. Not only will the spacecraft stay in orbit around the comet for a year, but it will also send the Philae Lander to its surface in November 2014.
Although past missions have done fly-bys of comets, this is the first time a spacecraft has ever been in a comet's orbit, and the mission itself was no small feat. Rosetta traveled almost 4 billion miles to reach its target, as its controllers used gravity from the planets to slingshot it at just the right angle. It spent two years in hibernation to save power, but reawakened in January 2014. A series of highly complex maneuvers recently slowed Rosetta down until it eventually caught up with the comet, where it is now orbiting.
Rosetta's next mission involves mapping the comet's surface, which will help determine where Philae will land. Once there, Philae will use a series of on-board scientific instruments that will examine the composition of the comet.
Scientists hope these instruments show those specific ingredients, or building blocks, that sustain life. Current theories about the origins of life involve comets bringing these specific materials to Earth and other planets, sparking the first signs of what we know as life.
Rosetta will also allow scientists rare insight into how comets change and evolve as they travel. When a comet gets close to the sun, its ice melts, which creates a tail of gas. Scientists hope to study this process, as well as get a better look at what the comet's nucleus looks like after this happens.
"We'll be able to make a comparison to now, when its relatively inert, to when it's highly active ... making this measurement over a year when we're riding alongside at walking pace and observing how a comet works and interacts with the sun," says Rosetta project scientist Matt Taylor.
Rosetta is too far away to see with the naked eye, but the ESA has set up a blog where the public can view images from Rosetta and get updates on the spacecraft's progress.
