Short answers, pulled from the story.
Rosetta was a European Space Agency probe launched on the 2nd of March 2004 to perform a detailed study of comet 67P/Churyumov-Gerasimenko. The mission cost approximately 1.3 billion euros and was the first to orbit a comet nucleus and deploy a lander, Philae, onto its surface.
Philae landed on comet 67P/Churyumov-Gerasimenko on the 12th of November 2014. It initially touched down at 15:33 UTC but bounced twice, coming to rest at 17:33 UTC in the shadow of a cliff, where limited sunlight caused its batteries to run out within three days.
The Philae lander detected sixteen organic compounds in the comet's atmosphere, including acetamide, acetone, methyl isocyanate, and propionaldehyde, four of which had never before been identified on a comet. The only amino acid detected was glycine, along with precursor molecules methylamine and ethylamine.
On the 30th of September 2016, the Rosetta spacecraft was guided to a controlled impact on comet 67P's surface in a region called Ma'at, at a site named Sais. The final data packet was received at the European Space Operations Centre in Darmstadt at 11:19:36.541 UTC, after which the spacecraft entered safe mode and went silent.
Early Rosetta data suggested 67P's water differed significantly from Earth's, with a deuterium-to-hydrogen ratio roughly three times that of terrestrial water. A re-analysis published in November 2024 identified a significant measurement error and concluded that 67P's water isotopic composition is actually similar to Earth's, keeping open the possibility that comets delivered water to Earth.
During its Mars gravity assist on the 25th of February 2007, Rosetta passed within 250 km of the planet and spent 15 minutes in Mars's shadow, where its solar panels received no light. The spacecraft flew on batteries not originally designed for the task, with no communication possible, risking the entire mission.