Rosetta finale set for 30 September

Rosetta approaching comet node full image 2

Title Rosetta approaching comet
Released 04/08/2014 5:38 pm
Copyright Spacecraft: ESA/ATG medialab; Comet image: ESA/Rosetta/NavCam – CC BY-SA IGO 3.0

Artist impression of ESA’s Rosetta approaching comet 67P/Churyumov-Gerasimenko.

The comet image was taken on 2 August 2014 by the spacecraft’s navigation camera at a distance of about 500 km.

The spacecraft and comet are not to scale.
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30 June 2016

Rosetta is set to complete its mission in a controlled descent to the surface of its comet on 30 September.

The mission is coming to an end as a result of the spacecraft’s ever-increasing distance from the Sun and Earth. It is heading out towards the orbit of Jupiter, resulting in significantly reduced solar power to operate the craft and its instruments, and a reduction in bandwidth available to downlink scientific data.

Where will Rosetta be on 30 September node full image 2

Title Where will Rosetta be on 30 September?
Released 30/06/2016 8:30 am

The location of Rosetta with respect to the Sun and several planets in the Solar System on 30 September 2016. On this day, Rosetta will be about 573 million km from the Sun and 720 million km from Earth. The one-way signal travel time will be about 40 minutes.

In addition, from 1 October, the teams would also be facing reduced communications due to ‘conjunction’. That is, the comet and spacecraft will be behind the Sun as seen from Earth – another contributing factor to concluding the mission by this time.

The image is a screenshot from the Where is Rosetta? tool.
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Combined with an ageing spacecraft and payload that have endured the harsh environment of space for over 12 years – not least two years close to a dusty comet – this means that Rosetta is reaching the end of its natural life.

Unlike in 2011, when Rosetta was put into a 31-month hibernation for the most distant part of its journey, this time it is riding alongside the comet. Comet 67P/Churyumov-Gerasimenko’s maximum distance from the Sun (over 850 million km) is more than Rosetta has ever journeyed before. The result is that there is not enough power at its most distant point to guarantee that Rosetta’s heaters would be able to keep it warm enough to survive.

Instead of risking a much longer hibernation that is unlikely to be survivable, and after consultation with Rosetta’s science team in 2014, it was decided that Rosetta would follow its lander Philae down onto the comet.

The final hours of descent will enable Rosetta to make many once-in-a-lifetime measurements, including very-high-resolution imaging, boosting Rosetta’s science return with precious close-up data achievable only through such a unique conclusion.

Communications will cease, however, once the orbiter reaches the surface, and its operations will then end.

Close-up view of the comet node full image 2

Title Close-up view of the comet
Released 30/05/2016 5:00 pm

During Rosetta’s final descent, the spacecraft will image the comet’s surface in high resolution from just a few hundred metres.

This OSIRIS narrow-angle camera image was taken on 28 May 2016, when the spacecraft was about 5 km from the surface of Comet 67P/Churyumov–Gerasimenko. The scale is 0.13 m/pixel.
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“We’re trying to squeeze as many observations in as possible before we run out of solar power,” says Matt Taylor, ESA Rosetta project scientist. “30 September will mark the end of spacecraft operations, but the beginning of the phase where the full focus of the teams will be on science. That is what the Rosetta mission was launched for and we have years of work ahead of us, thoroughly analysing its data.”

Rosetta’s operators will begin changing the trajectory in August ahead of the grand finale such that a series of elliptical orbits will take it progressively nearer to the comet at its closest point.

“Planning this phase is in fact far more complex than it was for Philae’s landing,” says Sylvain Lodiot, ESA Rosetta spacecraft operations manager. “The last six weeks will be particularly challenging as we fly eccentric orbits around the comet – in many ways this will be even riskier than the final descent itself.

“The closer we get to the comet, the more influence its non-uniform gravity will have, requiring us to have more control on the trajectory, and therefore more manoeuvres – our planning cycles will have to be executed on much shorter timescales.”

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