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Rosetta goes into orbit around comet

August 7, 2014



Europe'sRosetta probe has arrived at a comet after a 10-year chase.

In a first for space history, the spacecraft was manoeuvred alongside a speeding body to begin mapping its surface in detail.

The spacecraft fired its thrusters for six and a half minutes to finally catch up with comet 67P/Churyumov-Gerasimenko.

"We're at the comet!" said Sylvain Lodiot of the European Space Agency operations centre in Germany.

"After 10 years, five months and four days travelling towards our destination, looping around the Sun five times and clocking up 6.4 billion km, we are delighted to announce finally 'we are here'," said Jean-Jacques Dordain, director general of Esa.

Launched on board an Ariane rocket in March 2004, Rosetta has taken a long route around our Solar System to catch up with comet 67P.

In a series of fly-pasts, the probe used the gravity of the Earth and Mars to increase its speed during the 6 billion km chase.

In Januarythey successfully woke the craft from its slumberas it began the final leg of the daring encounter.

For the past two months, Rosetta has been carrying out a series of manoeuvres to slow the probe down.

The comet is travelling at 55,000km per hour. The spacecraft's speed has been adjusted so that in relative terms it will be flying beside the comet at a slow walking pace of 1m/sec.

At a distance of 550 million km from the Earth, messages are taking over 22 minutes to get to Rosetta.

The distances involved are so great that the complex final command sequence for Wednesday's crucial thruster burn had to be issued on Monday night.

"This arrival phase in fact is the most complex and exotic trajectory that we have ever seen," said Jean-Yves Le Gall, president of the French Space Agency CNES.

Rosetta will have to continue to fire its thrusters every few days to maintain a hyberbolic orbit at 100km above the rotating rock.

The craft will then travel alongside the comet for the next 15 months, studying it with a range of instruments.

Rosetta has been taking increasingly detailed photographs of 67P as it gets closer. The mysterious comet has been dubbed the "rubber duck", as some images seem to show the familiar shape as it twirls in space.

Project scientist, Dr Matt Taylor, said: "For me this is the sexiest, most fantastic mission there's ever been. It's ticking a number of boxes in terms of fascination, exploration, technology and science - predominantly science."

As it moves towards the Sun, 67P will warm up and its trailing halo of gas and dust - known as the coma - will increase, offering the orbiter the chance to do some detailed scientific work.

"We've seen evidence of the out-gassing of the coma, the outer atmosphere of the comet, this is made of dust and gas," said Dr Taylor.

"We have instruments on board that will start sniffing for this gas and taste it, we will also be collecting some of this dust and touching the coma itself. Hopefully that will occur sometime this week."

The mission gets even more ambitious in November when, after moving Rosetta closer to 67P, mission controllers will attempt to put the Philae lander on the surface.

The lander will use harpoons to anchor itself and will carry out a series of experiments, including drilling into the material that makes up the comet.

The mission aims to add to knowledge of comets and their role in ferrying the building blocks of life around the early Solar System.

Rosetta key facts

Total cost of the mission is said to be 1.3bn

The probe weighed in at 3,000kg at liftoff back in 2004, with over half of that made up of propellant

It has two 14m long solar panels to provide electrical power

The orbiter carries 11 experiments

The lander, Philae, carries nine experiments including a drill to sample beneath the surface


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Source: Malta Independent, The


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