Reaching 67P/Churyumov–Gerasimenko with Rosetta was an incredible feat of science and engineering that has revolutionized how we understand comets, but the fact is that the orbiter and its Philae partner are just entering the interesting part of their mission. Join us as we take a look at what can be expected as Rosetta travels ever closer to the Sun.

The point of closest proximity to the Sun is known in scientific circles as perihelion, and represents the holy grail to the Rosetta team in its pilgrimage to better understand the wandering bodies. Perihelion is currently expected to take place at 2:03 GMT on August 13 2015, and will see 67P pass within 186 million km (116 million miles) of the Sun.

Many comets simply plunge into the Sun at perihelion, however 67P has survived numerous orbits of our star, and at its closest point will still be farther away from the Sun than Earth's standard orbit. That said, whilst scientists at ESA are confident that the comet will survive perihelion, they can not rule out the possibility the the comet will disintegrate.

So what can we expect from the comet during this exciting phase? Well, comets are like time capsules that allow us to observe the building blocks of our solar system. By following one as it approaches and subsequently distances itself from perihelion, we get to see for the first time how these bodies evolve over the course of an orbital period.

ESA graphic displaying 67P's orbit and the point of perihelion(Credit: ESA)

We are already observing dramatically increased levels of outgassing activity from the 67P compared to when Rosetta arrived in August of last year. This increase in activity is due to solar energy emanating from our star, causing materials within the comet to sublimate, ejecting materials from the nucleus of the comet and adding to 67P's already impressive coma.

Earlier this month it was announced that Rosetta had discovered sinkholes present on the surface of 67P, and that sublimation from the walls of these pits are responsible for some of the active streams that the orbiter had been observing. This is just one example of how the mission is revolutionizing our understanding of the nature of comets.

Comet activity between 31 January (top left) and 25 March (bottom right)(Credit: ESA/Rosetta/NAVCAM – CC BY-SA IGO 3.0)

As the comet approaches the Sun, no special maneuvers will be required from Rosetta, which will continue to gather as much data as possible. Scientists at ESA are hoping that the newly-awoken Philae lander will provide a helping hand, assuming that both comet and orbiter will survive the encounter and continue to operate as 67P moves away from the Sun on its six-and-a-half-year orbital journey.

It is expected that a few months after the comet's close brush with the Sun, activity will have subsided enough to allow Rosetta to orbit closer to the nucleus and assess any changes to the structure of the wandering celestial body. The comet-chasing mission which has captured the attention of a global audience is due to come to an end in September 2016, with Rosetta set to become a surface feature on the comet that has been the focus of its operational life.

Source: ESA

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