Europe's ground-breaking quest to unravel the Solar System's mysteries concludes Friday with the Rosetta comet chaser crashlanding onto the cosmic wanderer's rocky surface.

The mission, summarised in numbers:

1: Rosetta became the first spacecraft, in August 2014, to enter the orbit of a comet. In November of that year, it sent down robot lab Philae, which became the first comet lander.

6.5 billion: Kilometres (four billion miles) travelled from Rosetta's launch in March 2004 until it reached Comet 67P/Churyumov-Gerasimenko, aided by gravity boosts on Earth and Mars flybys. By now, the accumulated distance is 7.9 billion km.

12 years, six months, 28 days: Mission duration from launch to end.

786: days Rosetta spent circling 67P, sniffing and tasting its atmosphere and photographing it from all angles.

19: kilometres (11 miles) -- the altitude from which Rosetta was set on a collision course with the comet.

14: hours -- the duration of Rosetta's freefall.

90: centimetres (35 inches) per second -- the speed at which Rosetta is to make a "controlled impact" with the comet.

720 million: kilometres (450 million miles) -- Rosetta's distance from Earth when it received its suicide command.

14.2: kilometres (8.7 miles) per second -- the speed of the comet, with Rosetta and Philae on deck, zipping around our Sun on a near seven-year elongated orbit.

40: minutes -- the time it took for signals to travel between mission control in Darmstadt and Rosetta.

11: Science instruments onboard Rosetta, added to another 10 on Philae.

100 kilograms (220 pounds) -- Washing machine-sized Philae's weight on Earth, compared to one gram (0.04 ounces) on the low-gravity comet. Rosetta weighs some three tonnes.

1.4 billion: euros ($1.5 billion), the cost of the mission, approved in 1993.

500: Number of scientists and engineers involved in the project.

SOURCE: European Space Agency