Philae, the bouncing lander
How the first comet landing went wrong, went right, and ended in a dark crevice found two years later.
Published 2026-10-23
On November 12, 2014, the lander Philae dropped from Rosetta toward Comet 67P. What followed was one of the most dramatic landings in space history.[6]
A landing designed for almost no gravity
67P's escape velocity is only around 1 m/s, so the challenge was not crashing — it was staying put. Philae's legs were designed to absorb the impact and drive ice screws into the surface, harpoons were meant to anchor it, and a thruster on top was to push it down.[6] Its target was Site J, renamed Agilkia after a public contest.[6]
Bounce, bounce, stop
At touchdown, the harpoons did not fire, the thruster did not work, and the ice screws did not grip.[6][4] Philae rebounded at 38 cm/s, rising to about 1 km, and bounced twice before coming to rest about two hours after first contact.[6][4] Even so, it achieved the first soft landing on a comet nucleus.[6]
Sixty-four hours
Philae ended up in a shaded spot that received only about 90 minutes of sunlight per 12.4-hour comet day — not enough to recharge its batteries.[6] Running on its primary battery, it transmitted images and data for about 64 hours, completing about 80% of its planned initial science before it fell silent.[6] It took the first images from a comet's surface and made the first on-site analysis of a comet nucleus.[6]
What Philae found
- Rather than “soft and fluffy,” the first touchdown site held a large amount of water ice beneath about 25 cm of granular material.[6]
- Its COSAC and Ptolemy instruments detected sixteen organic compounds, four seen on a comet for the first time.[6]
A brief reawakening
On June 13, 2015, as the comet neared the Sun, Philae sent an 85-second message: it was healthy and had recharged enough to wake up. Several intermittent contacts followed, but communication was eventually lost.[6]
Found at last
On September 2, 2016, weeks before the end of the mission, Rosetta's narrow-angle camera finally spotted Philae wedged in a dark crevice.[6][4]
Numbered citations link to the sources list on the Comet 67P/Churyumov–Gerasimenko overview page.