Small bodies · Space Codex
67P/Churyumov–Gerasimenko
A duck-shaped comet about 4 km long, less dense than water ice.
The comet Rosetta orbited
At a glance
Key points
ESA's Rosetta orbited it for two years and its Philae lander made the first landing on a comet.
- First comet orbited by a spacecraft
- First landing on a comet (Philae, 2014)
- Less dense than water ice
A fluffy world
With about half the density of water ice, 67P is a porous mix of dust and ice. Rosetta watched it wake as it neared the Sun in 2015, with jets erupting from cliffs and pits.
A ten-year chase
Rosetta launched on 2 March 2004 and needed three Earth flybys and one of Mars to match the comet's orbit, photographing the asteroids Steins and Lutetia along the way. To save power it slept for 31 months, from June 2011 until 20 January 2014, then caught up with 67P that August and stayed with it through perihelion on 13 August 2015.
What Rosetta found
Its mass spectrometer found water carrying more than three times the deuterium of Earth's oceans, evidence against comets like 67P being the main source of Earth's water. It detected abundant molecular oxygen, the first seen at a comet, and the amino acid glycine together with phosphorus, two ingredients of biology. None of this means life; it shows comets carried complex chemistry from the young Solar System.
Philae's bumpy landing
Philae bounced twice after its first touchdown at Agilkia and came to rest in shadow at a site later named Abydos. Its main battery ran out after about three days. It woke briefly in June and July 2015 as more sunlight reached it, and was finally spotted wedged in a dark crack in an image taken on 2 September 2016, weeks before Rosetta's own descent.
What we still don't know
Whether its two lobes formed separately and merged, as the layering suggests, and how much of its water resembles Earth's.
Missions
- 2004–2016
Rosetta / Philae
ESACompletedFirst comet orbiter; Philae made the first comet landing on 12 Nov 2014.
Related entries
- 1P/HalleyThe most famous comet
Sources
- Bieler et al. 2015, molecular oxygen at 67P, Nature (opens in a new tab)
- Altwegg et al. 2016, glycine and phosphorus at 67P, Science Advances (opens in a new tab)
- ESA: Philae found! (opens in a new tab)
- JPL Small-Body Database: 67P (opens in a new tab)
- ESA: Rosetta fact sheet (opens in a new tab)
- Altwegg et al. 2015, Science (opens in a new tab)
- NASA JPL: Horizons ephemeris system (opens in a new tab)
Last reviewed against these sources. Built from public NASA, ESA and JPL data; not affiliated with or endorsed by any agency.