Early on Wednesday, the Rosetta spacecraft – launched over a decade ago – rendezvoused with the 67P/Churyumov-Gerasimenko comet as planned. The spacecraft will now accompany the comet on its solar orbit for a year.
— ESA Rosetta Mission (@ESA_Rosetta) August 6, 2014
This is a first for humanity, and it should give us an unprecedented view into the nature of comets. Rosetta is currently accompanying the comet from a 100-km (62-mile) distance, but the European Space Agency (ESA), which is behind the mission, hopes to get closer than 30 km. Rosetta already studied a couple of asteroids in close detail while en route to its date with 67P.
“After ten years, five months and four days traveling towards our destination, looping around the Sun five times and clocking up 6.4 billion kilometers, we are delighted to announce finally ‘we are here,'” ESA Director-General Jean-Jacques Dordain said in a statement.
As Rosetta approached 67P over recent months, it was already able to take certain measurements – the comet is apparently spitting out 300 milliliters of water vapor each second and its average temperature is around -70 degrees C (-94 degrees F). As you can see in the above image, it has two distinct segments, and the ESA is keen to figure out whether that’s the result of erosion or the ancient fusion of two separate comets.
In the coming months, the ESA scientists will try to find a good landing spot for the Philae lander, which will attach itself to the surface with harpoons. Philae has 10 scientific instruments on board for analysing the dark, dusty comet’s composition.