Goals: The European Space Agency's Rosetta was the first mission designed to orbit and land on a comet. It consisted of an orbiter and a lander -- called Philae. The two spacecraft carried 20 science instruments to make a detailed study of comet 67P/Churyumov-Gerasimenko for two years as it orbited around our sun.
Accomplishments: In August 2014, Rosetta became the first spacecraft to orbit a comet when it joined comet 67P/Churyumov-Gerasimenko on it's journey around the sun. On 12 November 2014, Rosetta scored another historic first when its Philae probe successfully landed on the surface of the comet and began sending back images and data.
The mission ended with a successful controlled impact on the comet on 30 September 2016.