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Rosetta analyses Comet 67P at perihelion


The European Space Agency’s Rosetta spacecraft observed Comet 67P/Churyumov–Gerasimenko making its closest approach to the Sun on 6 August. The exact minute of perihelion occurred at 3:03 a.m. BST on 13 August when the comet came within 186 million kilometers (116 million miles) of the Sun.
In 2014 since Rosetta arrived, the comet has travelled 750 million kilometers along its orbit towards the Sun, the amplifying solar radiation heating up the center and causing its frozen ices to escape as gas and stream out into space at an ever larger rate. These dust particles and the gases that they drag along build up the comet’s atmosphere – coma – and tail.
The activity reaches its highest intensity around perihelion and in the weeks that follow – and is evidently visible in the spectacular images returned by the spacecraft in the previous months. One image taken by Rosetta’s navigation camera was obtained from a distance of around 327 kilometers (203 miles), at 2:04am GMT, just an hour before the moment of perihelion.
The precise camera is also taking images yesterday – the recent available image was taken at 12:31am BST on 13 August, just a few hours before perihelion. The comet’s motion is clearly seen in the images, with a massive amount of jets stemming from the nucleus, including one explosion captured in an image taken on 12 August at 6:35pm BST.

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This succession of images of /Churyumov–Gerasimenko was taken by Rosetta’s OSIRIS narrow-angle camera on 12 August 2015, just a few hours before the comet reached the closest position to the Sun, or perihelion, along its 6.5-year orbit. The pictures were taken from a distance of approximately 330 kilometers from the comet. The activity of Comet 67P at its peak intensity around perihelion is evidently observable in this spectacular animation.

Credit: ESA/Rosetta/MPS for OSIRIS Team MPS/UPD/LAM/IAA/SSO/INTA/UPM/DASP/IDA.

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This image of Comet 67P/Churyumov–Gerasimenko was taken by Rosetta’s OSIRIS narrow-angle camera at 17:35 GMT on 12 August 2015, just a few hours before the comet reached perihelion.

Credit: ESA/Rosetta/MPS for OSIRIS Team MPS/UPD/LAM/IAA/SSO/INTA/UPM/DASP/IDA.

“Activity will remain high like this for many weeks, and we’re certainly looking forward to seeing how many more jets and outburst events we catch in the act, as we have already witnessed in the last few weeks,” says Nicolas Altobelli, acting Rosetta project scientist.
Rosetta’s measurements suggest the comet is emitting up to 300kg of water vapor – roughly the equivalent of 2 bathtubs – every second. This is a thousand times more than was detected this time last year when Rosetta first approached the comet.
Sylvain Lodiot, ESA’s spacecraft operations manager comments “In recent days, we have been forced to move even further away from the comet. We’re currently at a distance of between 325 and 340 kilometers this week, in a region where Rosetta’s star trackers can operate without being confused by excessive dust levels – without them working properly, Rosetta can’t position itself in space”.

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