Europe's comet-chasing space probe Rosetta dipped out of orbit Friday with a slow-motion crash onto the icy surface of the alien world it's been following for more than a decade.
Its final radio signals arrived at the mission operations center in Darmstadt, Germany at 7:20 a.m. EDT after it hit Comet 67P/Churyumov-Gerasimenko at a speed of 2 miles per hour, slower than a walk.
"Goodbye @ESA_Rosetta what an adventure! We'll be busy with your #comet science for a long time to come #CometLanding," the European Space Agency wrote in a tweet.
Scientists sent their final command to the probe late Thursday, ordering Rosetta to fire its thrusters for 208 seconds and perform a last series of scientific measurements concluding its 12-year mission. Because of the distance between the comet and Earth, news of the landing took about 40 minutes to reach ESA's mission control.
Jan Woerner, the head of the ESA, said the 1.4 billion euro ($1.57 billion) mission was already a success. Aside from sending a lander onto the surface of the comet in November 2014 — a cosmic first — the Rosetta mission has collected vast amounts of data that researchers will spend many more years analyzing.
Scientists have already heralded a number of discoveries about the chemical composition of the comet that provide crucial insights into the formation of the solar system and theories about the origin of life on Earth.
The landing takes place at about 90 centimeters per second — roughly half walking speed — giving Rosetta a chance to snap some unprecedented low-altitude images of the comet that could reveal surface features as small as an inch (2.5 centimeter).
Andrea Accomazzo, the spacecraft operations manager, said the mission had been a huge challenge and should be considered an achievement "not just for ESA, but for mankind." Should Earth ever be threatened by an asteroid, the experience gained from the Rosetta mission would prove valuable, he said.