A view of Comet 67P/Churyumov-Gerasimenko taken by Rosetta’s OSIRIS narrow-angle camera on Aug. 3 from a distance of 177 miles. (European Space Agency image.)

The European Space Agency’s Rosetta spacecraft achieved orbit around Comet 67P/Churyumov-Gerasimenko on August 6. Ten years on the way, traveling four billion miles and aided by four gravity assists (three from Earth and one from Mars), Rosetta will escort the comet as it swings around the Sun and heads back toward Jupiter.

The Alice ultraviolet imaging spectrometer.

Rosetta will study the comet an OSIRIS camera, a MIRO miniature radio telescope, an Alice ultraviolet (UV) spectrograph, an Ion and Electron Sensor (IES) and other instruments.

Rosetta also carries a lander, Philae, that will be dropped on the comet’s surface in November 2014, where it will drill, extract and analyze samples, and send pictures back to Earth.

Based on temperature readings made by Rosetta’s instruments, scientists already have surmised that the comet has a porous, dusty crust with ice beneath. The surface is strewn with boulders the size of houses, and Churyumenko-Gerasimov’s icy cliffs rise as high as 500 feet (150 meters).

Rosetta initially will orbit about 60 miles from the comet, but eventually will move in closer, about 12 to 20 miles away.

Update 08/07/2014: Corrected misspelling of “ultraviolent” spectrograph.