Are we there yet? Yes.
This morning, after a journey through the solar system of more than 10 years, the Rosetta spacecraft arrived at the comet 67P/Churyumov-Gerasimenko. The mission, perhaps the most ambitious one ever undertaken by the European Space Agency (ESA), will now join the comet as it begins a lap around the sun, heats up, and releases stores of ice in a cloud of dust and gas.
By arrival, ESA managers mean a rendezvous at a distance of 100 kilometers. But the spacecraft will get even closer. The spacecraft is now flying triangles in front of the comet and beginning the frantic job of mapping it—necessary to calculate the comet’s irregular microgravity field. But in several weeks, Rosetta will settle into a orbit of 30 kilometers—and it may attempt orbits even closer than that, if the comet’s activity level will allow. In November, the spacecraft will swoop low over the surface at an altitude of just several kilometers and drop the Philae lander, which will sample the comet—if the lander’s two harpoons can keep it stuck to the surface.
Pictures released on Wednesday show what ESA senior scientist Mark McCaughrean called “the most crazy bonkers comet in the solar system”—a bulbous, bilobed object that will surely be difficult to land on. But mission managers are excited for the challenge ahead. “I think it’s just a spectacular object,” McCaughrean says.