A European spacecraft has become the first in history to rendezvous with a comet after a seven-minute burn of the probe’s thrusters brought it within 100km of the hurtling lump of dust and ice.
The European Space Agency's billion-euro Rosetta spacecraft caught up with comet 67P/Churyumov-Gerasimenko more than 400 million km from Earth as it streaked towards the sun at about 55,000km/h.
The manoeuvre that brought the spacecraft alongside the comet marks the end of the beginning of a mission that lifted off from French Guiana more than 10 year ago. Rosetta now begins its scientific mission, employing a suite of instruments to analyse the comet's nucleus.
The Rosetta mission will be the first to give scientists close-up measurements of a comet as it transforms from a cold and inactive state to an active body that sheds hundreds of kilos of dust and gas as it swings around the sun.
The comet is in a 6.5-year elliptical orbit that comes within the orbits of Mars and Earth and back out to beyond the gas giant Jupiter.
“After 10 years, five months and four days travelling towards our destination, looping around the sun five times and clocking up 6.4bn kilometres, we are delighted to announce finally, we are here,” said ESA’s director general Jean-Jacques Dordain.
"Europe's Rosetta is now the first spacecraft in history to rendezvous with a comet, a major highlight in exploring our origins. Discoveries can start."
Wednesday’s manoeuvre at 9am GMT was the last in a series of 10 burns that tweaked the speed and trajectory of the spacecraft in its approach to the comet. Images taken of the comet reveal an extraordinary rubber duck-shape, the result of two bodies fusing in what space scientists call a contact binary.
Over the coming weeks, Rosetta will fly in a strange triangular orbit around the comet and map its terrain and gravitational field. Once mission controllers feel they understand the body, they will move Rosetta into a closer orbit within 30km of the surface.
Sensors aboard Rosetta will gather and analyse gas and dust that start to spew from the comet as it becomes more active and develops a huge tail that could stretch for a million kilometres.
Mission controllers are working against the clock to identify a safe spot on the surface to place a small lander called Philae, which is hitching a ride on Rosetta. The space agency aims to land Philae on November 11th. The box of electronics on legs will latch on to the comet with the aid of an explosive harpoon. With Philae in place, scientists will have their first opportunity to analyse material collected directly from the comet. The lander will also send X-rays through the comet's nucleus to sensors on Rosetta to reveal the inner structure of the body. – (Guardian service)