Why. Rosetta's mission was to rendezvous with Comet 67P/Churyumov-Gerasimenko, study its nucleus and environment for nearly two years and land a probe on its surface. It was the first mission to follow a comet on its orbit around the Sun.
Source: ESA, Rosetta factsheet, page dated Jul 25, 2014; ESA, Rosetta, no date on the page. Checked Nov 13, 2026.
When. Launched on March 2, 2004 on an Ariane 5. After 31 months of deep-space hibernation it woke up in January 2014 and arrived at the comet on August 6, 2014. On November 12, 2014 the Philae lander descended to the surface.
Source: ESA, Rosetta's frequently asked questions, page dated Mar 3, 2004; ESA, Mission complete: Rosetta’s journey ends in daring descent to comet, page dated Sep 30, 2016; ESA, Rosetta: Comet rendezvous, page dated Jan 22, 2004; ESA, Rosetta, no date on the page; ESA, Philae found!, page dated Sep 5, 2016. Checked Nov 13, 2026.
What it did. Rosetta was the first spacecraft to orbit a comet and the first to deploy a lander onto one. Philae failed to anchor, bounced and came to rest in a less well illuminated spot, yet it completed many experiments, detecting 16 organic compounds, four of them never before seen in comets. Rosetta itself detected the amino acid glycine and phosphorus, and less than a month before the end of the mission it photographed Philae wedged in a dark crack.
Source: ESA, Mission complete: Rosetta’s journey ends in daring descent to comet, page dated Sep 30, 2016; ESA, The Rosetta lander, page dated Nov 25, 2002; ESA, Science on the surface of a comet, page dated Jul 30, 2015; ESA, Philae found!, page dated Sep 5, 2016. Checked Nov 13, 2026.
How it ended. With the comet carrying Rosetta out beyond the orbit of Jupiter, where there would be too little power to operate, the team chose to end the mission on the surface. On September 30, 2016 Rosetta made a controlled impact onto the comet; its signal was lost at 11:19 GMT, and it is no longer possible to communicate with the spacecraft.
Source: ESA, Mission complete: Rosetta’s journey ends in daring descent to comet, page dated Sep 30, 2016. Checked Nov 13, 2026.