European scientists have sent the Rosetta spacecraft on its final, one-way journey to the surface of a comet, after a historic 12-year mission to discover the secrets of the dusty, icy bodies.
The Rosetta spacecraft has been chasing comet 67P/Churyumov–Gerasimenko across more than 6 billion kilometers (3.7 billion miles) of space, collecting a treasure trove of information on comets that will keep scientists busy for the next decade.
On Thursday evening, the European Space Agency confirmed the spacecraft had started its "collision maneuver", putting it on course to crash into the comet within 20 minutes of 1040 GMT on Friday.
"We want to go out at the peak of capability. We don't want a comeback tour that's rubbish. We will end in a very rock-and-roll fashion," project scientist Matt Taylor told Reuters earlier on Thursday.
During its descent, Rosetta's instruments and camera will relay back data and images, giving scientists insight into the structure of the comet.
The descent will reveal information on the side walls of the comet, crucial to understanding how comets formed, plus on large 100-metre (109-yard) wide pits, which scientists believe are key to how the comet releases gas and dust as it is warmed by the sun.
The mission has managed several historic firsts, such as getting a spacecraft into orbit around a comet and the unprecedented landing of a probe on the surface of a comet. A handful of previous spacecraft snapped pictures and collected data as they flew past their targets.
Data collected by Rosetta and lander Philae, which reached the surface in November 2014, is already helping scientists better understand how the Earth and other planets formed.
For example, scientists now believe that asteroids, not comets were primarily responsible for delivering water to Earth and other planets in the inner solar system, possibly setting the stage for life.
"We've just scratched the surface of the science. We're ending the mission, but the science will continue for many years," Taylor said.
Rosetta will free-fall into the comet at the speed of a sedate walk, but it is not designed to withstand the impact.
The European Space Agency is ending the mission because 67P is racing toward the outer solar system, out of range for the solar-powered spacecraft.
Rosetta also has been subjected to the harsh radiation and extreme temperatures of space since launching in March 2004 and is unlikely to last too much longer
(Reporting by Victoria Bryan; Additional reporting by Irene Klotz in Guadalajara, Mexico and Tilman Blasshofer in Frankfurt; Editing by Sandra Maler)