Rosetta has arrived! Probe successfully goes into orbit around comet after a series of nail-biting manoeuvres
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After ten years and four billion miles, Rosetta has finally caught up with its comet following a series of spectacular manoeuvres.
The tiny probe is now in orbit within 62 miles (100km) of comet 67P/Churyumov-Gerasimenko which is travelling at 34,000 mph (55,000 km per hour).
Described as 'the sexiest, most fantastic mission ever', Rosetta will spend more than a year analysing the comet to help uncover the secrets to life on Earth.
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'Hello, Comet!': Esa today released the latest image of comet 67P/Churyumov-Gerasimenko on Twitter. The tiny probe is now in orbit within 62 miles (100km) of the comet after a decade-long chase through the solar system
During the hotly anticipated rendezvous, Rosetta edged closer to its target adjusting its speed so that it was flying beside the comet at a slow walking pace of 1m/sec (2.2mph, 3.6kph).
Mission controllers had to wait an nail-biting 22 minutes to know that the manoeuvre had been successful.
The successful manoeuvre marks beginning of a series of weekly thruster burns that will take place every Wednesday and Sunday well into 2015 to keep the spacecraft in orbit around the comet.
Rosetta's initial orbit will see it travel around the comet in a three-legged triangular path with a small thruster burn at each 'end' of the triangle.
Each leg of this triangle is about 62 miles (100km) long, and it will take Rosetta about three or four days to traverse each leg.
A timeline of Rosetta's journey to comet 67P. The probe was launched in March 2004 from Kourou in French Guinana. In January this year, after 3 years, Rosetta woke up from hibernation to chase down its comet
The probe flew into space more than a decade ago and had to perform a series of complex manoeuvres to gain enough speed to chase down comet 67P/Churyumov-Gerasimenko.
Previous missions to study comets have been brief fly-bys to gather data or collect samples of dust.
Rosetta, however, will fly around comet 67P in a form of orbit for more than a year, using its 20 instruments to collect data.
Scientists hope the mission will reveal more about the origins of comets and other celestial bodies.
If all goes according to plan the probe will also drop a small landing craft, named Philae, onto the comet's icy surface in November.
One surprise in the lead up to the event was the comet's bizarre shape, with what look like two parts joined together.
The comet has been dubbed the 'rubber duck' in space and recent photos have revealed that its target, 67P/Churyumov-Gerasimenko is actually what is known as a 'contact binary'.
This means it is likely two comets stitched together, in what could turn out to be both a blessing and a curse.
It could have been fractured in the past or it could be two different objects that very slowly came into contact at speeds of a few metres per second.
This irregular structure makes it harder for scientists to calculate the comet's gravitational pull, to help steer the probe.
Rosetta recently measured the temperature of the comet and determined that its average surface temperature is about -70°C (-94°F).
Click on the image below to view Rosetta's current position
THE ROSETTA MISSION
Rosetta is named after the Rosetta Stone, a slab of basalt containing inscriptions that helped archaeologists decipher ancient Egyptian hieroglyphs.
The mission will seek to help scientists unlock the composition of comets and thereby understand more about the origins and evolution of our solar system.
The probe was launched in 2004 and has since travelled around the sun five times, picking up energy from Earth and Mars to line it up with its final destination: Comet 67P/Churyumov–Gerasimenko.
For the coldest, loneliest leg of the mission, as Rosetta travelled out towards the orbit of Jupiter, the spacecraft was put into deep-space hibernation.
Rosetta has now entered orbit around the comet. It will place its Philae lander onto the comet's surface in November.
While in orbit it will perform extensive analysis of the comet's composition, which will provide scientists with an insight into the history of the solar system and help to discover the origin of comets.
Although it may seem cold, that is actually 20 to 30°C (36 to 54°F) warmer than predicted for a comet at that distance, suggesting its surface will be quite dusty in addition to being icy.
Speaking to MailOnline Pedro Lacerda, astrophysicist at the Max Planck Institute for Solar System Research and part of the team analysing results of the Rosetta mission, said: '67P does seem to be made of two lumps.
'On one hand this is unexpected, because the shape model we had based on observations from Earth didn't predict a binary structure. That just highlights the importance of these missions - they tell us more.
'On the other hand, three of the five comets previously visited by spacecraft seem to be composed of two chunks too, so it could be that binary comets are quite common.
'Now we need to find out what this is telling us. Is this a result of the way comets form, or is it a consequence of their evolution?
'Hopefully, Rosetta will point us to the answer. The Kuiper belt, where this comet is believed to originate, seems to have a very high fraction of binaries, up to 30 per cent depending on where you look, which is also interesting.
'Where do we land so that we maximise the science return? Technically, it probably does not change much. The landing will be challenging no matter what.'
The comet is about 2.5 miles (four km) long and orbits the sun every six-and-a-half years. It is heading towards the sun, so as it nears the star it will begin to melt more.
For a sense of scale, the comet is about three times the size of Ben Nevis and Rosetta is the size of a car with 105ft (32-metre) wings.
Images of comet 67P/Churyumov-Gerasimenko taken on July 14, 2014, by the Osiris imaging system aboard the Rosetta spacecraft have allowed scientists to create this three-dimensional shape model of the nucleus
The Rosetta spacecraft (artist's illustration shown) have become the the first spacecraft to orbit a comet
The comet as seen from the Rosetta probe throughout July and August. Rosetta recently measured the temperature of the comet and determined that its average surface temperature is about -70°C (-94°F)
WHAT IS A CONTACT BINARY?
A contact binary occurs when two celestial objects, such as asteroids or comets, slowly move towards each other until they are touching.
The slow approach of the two means they will form a single-oddly shaped body, rather than rebounding of one another.
Nine near-Earth objects are known to be contact binaries.
However, it is estimated that as many as 15 per cent of all near-Earth asteroids more than 650 feet (200 metres) in size are actually contact binaries.
Even though it is still more than 370 million miles (600 million km) from the sun - more than four times the distance between Earth and sun - its surface has already started to warm, causing its ices to turn to gas and escape from its rock-ice nucleus.
As the gas escapes, it also carries a cloud of tiny dust particles out into space, which slowly expands to create the coma.
The warming will continue as the comet moves closer to the sun and activity rises, and pressure from the solar wind will eventually cause some of the material to stream out into a long tail.
This will give Rosetta some fascinating opportunities to observe the comet's emissions and find out more about its composition.
Rosetta and the comet will be closest to the sun in August 2015, when they will be between the orbits of Earth and Mars.
Information from the mission is expected to help scientists understand the origin of comets, the solar system, and possibly life.
Comets are known to contain complex organic molecules rich in carbon, hydrogen, oxygen and nitrogen - the basic elements that make up the essential ingredients for life, nucleic and amino acids.
Many scientists believe comets may have helped to plant the seeds of life on Earth.
In November of this year the Philae lander will be sent to touch down on the surface of the comet (artist's illustration shown), which will be the first landing ever performed on a comet. Here, harpoons will be fired into the surface to keep it anchored while it studies its surroundings
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