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The arrival of Esa's Rosetta spacecraft at its comet target is tantalisingly close, with arrival set to take place on Wednesday.

And images released by the space agency have revealed the stunning icy rock that awaits the probe as it nears the climax of its mission.

The 'rubber duck' shape of the comet is clearly seen in the latest images taken from a distance of just 620 miles (1,000 km) - roughly the distance of London to Berlin.

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Esa is preparing for Rosetta's arrival at its target on Wednesday, and it has released images showing the comet's surface in unprecedented detail. The images confirm 'rubber duck' shape of Comet 67P/Churyumov-Gerasimenko This one, taken a few days ago, shows the comet at a distance of just 620 miles (1,000 km) away

Of course the spacecraft is getting closer all the time, and as of today it is less than 310 miles (500 kilometres) from Comet 67P/Churyumov-Gerasimenko.

This followed yesterday's orbit correction manoeuvre (OCM), which decreased Rosetta's speed by 10.5ft (3.2 metres) per second.

A final burn of 3.3ft (one metre) per second will enable Rosetta to begin a complex dance around the comet that will eventually see it enter a stable orbit.

This week also marks the beginning of a series of weekly thruster burns that will take place every Wednesday and Sunday well into 2015 that will keep the spacecraft in orbit around the comet.

Its 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 (100 kilometres) long, and it will take Rosetta about three or four days to traverse each leg.

Rosetta also recently measured the temperature of the comet and determined that its average surface temperature is about -70°C (-94°F).

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.

This image was taken by Rosetta's Navcam. The publication of images follows controversy over Esa's release policy. One science writer had compared Esa's refusal to make images and data publicly available to not showing the World Cup live on TV. But a compromise has been reached with Esa releasing an image a day

The Rosetta spacecraft launched in 2004 on a mission to study comet 67P/Churyumov-Gerasimenko (artist's illustration shown). It will rendezvous with the comet later this month before entering orbit in August, becoming the first spacecraft to orbit a comet

Some controversy has surrounded the Rosetta mission recently, however, as scientists have been pressuring Esa to be more open about the mission.

Space enthusiasts have become accustomed to being granted access to most images and data as soon as they are taken - for example, Nasa's Curiosity rover on Mars releases all its raw images to the public immediately, even before they have been studied by scientists.

Esa, however, is being very protective of its Rosetta mission and has been holding on to much of the images and data - to the annoyance of many scientists.

This, Esa says, is to give their science teams an opportunity to study the data and produce research before others can.

But others have suggested the wait for data - which will be up to six months in some instances - will detract from the mission as it happens.

'Imagine it's the soccer World Cup final, but you can't watch it live on TV,' space science writer Daniel Fischer says in New Scientist.

'The sport's governing body has decided that all but a few sample photos of it will be embargoed for half a year, and that all decisions by the referee will have to be reviewed by experts over the coming months before a winner can be announced.

'Sounds silly? This is pretty much how many space enthusiasts experienced the countdown to the final phase of Europe's much-anticipated Rosetta mission.'

Following the criticism Esa has supposedly agreed to a compromise, reports The Independent, with the agency agreeing to release at least one image from the probe every day, although the rest will be kept under wraps to be revealed at a later date.

Earlier this month, remarkable photos showed that Rosetta's target, 67P/Churyumov-Gerasimenko is actually what is known as a 'contact binary', garnering huge public interest and highlighting the case for giving the public immediate access to images and data.

It is likely that the target is 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. 

Stunning images of the comet Rosetta is heading towards were released last month. Shown here, they reveal that the comet previously thought to be a single object actually has two parts. How these two parts came to be is not known, but more information will be gleaned in the next few months

What is certain, though, is that it poses some intriguing problems for Rosetta.

The most notable will be the planned landing of the Philae probe on its surface in November.

This will be the first cometary landed ever attempted - but now a decision will be made on what part of the comet to land on.

Regardless, Rosetta is still planning to enter orbit around the comet on Wednesday 6 August.

The orbit will gradually be lowered to 19 miles (30 kilometres) once the gravitational field of the comet is known - which could be more odd than expected given its shape.

According to Philae navigator Eric Jurado, 'navigation around such a body should not be much more complex than around a nucleus of irregular spherical type.'

But, he adds, 'landing the Philae probe, however, could be more difficult, as this form restricts potential landing zones.'

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 believe 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.

'It could be that many of these objects start out as binaries.

'In terms of the landing, I think the binary shape just raises more interesting questions.

'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.'

Rosetta has been firing its thrusters to cut by almost two thirds the speed with which it's hurtling towards the comet.

There will be a total of four before Rosetta comes within 62 miles (100 kilometers) of the comet in early August, beyond the orbit of Mars.

The final rendezvous will require two more precision maneuvers.

The probe, launched a decade ago, will spend time observing 67P before dropping a lander called Philae onto its icy surface in November.

If the Philae lander is successful it will become the first vehicle ever to land on a comet.

The comet is about 2.5 miles (four kilometres) long and orbits the sun every six-and-a-half years.

Once at the comet Rosetta will follow it on its journey around the sun, performing extensive studies of the coma and the surface.

The spacecraft's speed will be slowed in order to remain in orbit, bringing it to roughly about walking pace relative to the comet.

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

The comet is heading towards the sun, so as it nears the star it will begin to melt more.

Even though it is still more than 370 million miles (600 million kilometres) 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.

On 25 Feb 2007 The Rosetta spacecraft returned this stunning image of Mars as it flew past the red planet on its way to the comet. The picture was taken by an imaging instrument on the Philae lander at a distance of 620 miles (1,000 kilometres). Below the solar array an area close to the Syrtis region is visible on the planet's disk