Rosetta and Philae
The first spacecraft to orbit a comet and to land on one.
Key facts
- Agency
- European Space Agency (ESA)
- Type of mission
- Comet orbiter and lander
- Target
- Comet 67P/Churyumov–Gerasimenko; asteroids Šteins and Lutetia
- Launched
- 2 March 2004
- Status
- Ended 2016
Rosetta spent ten years catching up with comet 67P/Churyumov–Gerasimenko. It used gravity assists from Earth three times and from Mars once, and passed two asteroids on the way. Šteins, about 5 kilometres across, is a rare E-type asteroid whose colours match the aubrites, meteorites made mostly of enstatite. Lutetia, about 100 kilometres long, is an ancient, heavily cratered body.
At the comet
After more than two and a half years asleep to save power, Rosetta woke in January 2014 and reached the comet on 6 August 2014. 67P turned out to be made of two lobes joined by a neck, about 4 kilometres long, shaped like a rubber duck. Rosetta followed it for over two years as it swung around the Sun, watching jets switch on, cliffs collapse and boulders move.
Philae
On 12 November 2014 the lander Philae touched down, but its harpoons failed to fire. It bounced twice and came to rest in shadow under a cliff, where it worked for about 60 hours before its batteries ran flat. Rosetta finally photographed it, wedged in a crack, in September 2016.
What Rosetta found
The comet is very porous, about half as dense as water. Its water has about three times as much heavy hydrogen, deuterium, as Earth's oceans, so comets like 67P cannot have supplied most of Earth's water. It released molecular oxygen, glycine, phosphorus and many organic molecules, and its dust grains were fluffy aggregates.
Rosetta ended its mission on 30 September 2016 with a slow, controlled descent onto the comet.
Key dates
| Date | What happened |
|---|---|
| 2 March 2004 | Rosetta launched on an Ariane 5 rocket. |
| 5 September 2008 | Flew past the asteroid 2867 Šteins. |
| 10 July 2010 | Flew past the asteroid 21 Lutetia. |
| 20 January 2014 | Woke from 31 months of hibernation. |
| 6 August 2014 | Arrived at comet 67P/Churyumov–Gerasimenko. |
| 12 November 2014 | Philae landed on the comet, the first landing on a comet. |
| 13 August 2015 | The comet passed closest to the Sun, with Rosetta watching. |
| 30 September 2016 | Rosetta ended its mission by descending onto the comet. |
See where this mission fits among all the others in the mission timeline.
Did you know?
Rosetta and Philae are named after the Rosetta Stone and an obelisk from the island of Philae, which together helped scholars read Egyptian hieroglyphs.
Comet 67P smells, according to its gases, of rotten eggs, ammonia and bitter almonds.
Related pages
Comets connected with this mission: Comet 67P/Churyumov–Gerasimenko, Comet Wirtanen. See all comets.