On November 12, 2014, a small washing-machine-sized probe named Philae separated from the European spacecraft Rosetta and descended toward the surface of a comet 511 million kilometers from Earth. After a seven-hour fall, it touched down on Comet 67P/Churyumov–Gerasimenko — the first, and so far only, landing on a comet in human history.
Ten Years and Four Billion Kilometers
The Rosetta mission was a marathon: launched in March 2004, it spent a decade chasing comet 67P through the inner solar system, circling the Sun four times and using three Earth gravity assists and one Mars assist to match the comet’s 135,000 km/h pace. Arriving in August 2014, Rosetta became the first spacecraft ever to orbit a comet, mapping the bizarre rubber-duck-shaped nucleus in unprecedented detail. The landing site, Agilkia, was chosen from candidate sites with names drawn from Egyptian geography — fitting for a spacecraft named after the Rosetta Stone.
The Harpoons That Didn’t Fire
The descent nearly failed twice. Philae’s cold-gas thruster system failed the night before, leaving the probe with only its landing legs and two harpoons to anchor itself to a body with almost no gravity. Then, during descent, its star trackers locked onto dust particles instead of stars, putting it into a slow tumble. It landed — but bounced. The harpoons had not fired; Philae hit the surface, rebounded for nearly two hours across the comet in the near-zero gravity, and came to rest wedged in a shadowed cliff, where its solar panels starved and its primary battery died after about 60 hours of science. In those hours, it drilled, hammered, sniffed and photographed — confirming organic molecules, including carbon-based compounds, on the comet’s surface.
The Long Nap and the Legacy
Philae slept for seven months until the comet’s orbit brought more sunlight; it briefly woke in June 2015, phoned home to Rosetta, and went silent again — found in 2016 by Rosetta’s camera, wedged on its side among boulders. Rosetta itself ended the mission with a controlled crash onto the comet on September 30, 2016. Twelve years on, November 12, 2014 remains humanity’s most audacious landing: a machine built on Earth, riding a comet through space, phoning home from 511 million kilometers away.
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