Last week we shared a shape model of comet 67P/C-G based on the previous week’s images. Now the OSIRIS team have used images taken from 14-24 July to create a revised, more detailed model. This model is a formal product delivered to the Orbiter and Lander Teams to aid with their preparations for orbiting around and, eventually, landing Philae on the comet.
Grab a pair of red-green/blue glasses to enjoy the anaglyph version, too!
The ultimate goal of the landing site selection process is to identify a safe and scientifically interesting site for Rosetta’s lander, Philae. A meaningful selection can only be made once the spacecraft is close enough to be able to characterise the comet surface and its environment, but preparations can start to advance now that the comet’s approximate shape and rotation properties are known.
Flight dynamics teams will need to plan the trajectories that are needed to safely navigate around the comet and to determine the best flight paths for delivering the lander to the surface.
But the landing site itself must also meet certain criteria. It must provide suitable illumination – an important factor for recharging the lander’s battery via on-board solar panels, and offer good visibility to the orbiter, as Philae relays information to Earth through mothership Rosetta. It must also be free from hazards such as large boulders or crevasses, features that can only be identified once Rosetta is much closer to the comet.
Next week, on 6 August, Rosetta arrives at the comet at a distance of about 100 km, moving down to about 50 km towards the end of the month. At the same time, five candidate landing sites will be selected for further detailed investigation.
Then, as Rosetta moves to a distance of just 30 km from the comet’s surface, more details of its surface will be revealed, allowing higher resolution imaging of the candidate sites. At an altitude of 30 km, the Narrow Angle Camera of OSIRIS will provide a surface resolution of 55 cm per pixel.
One primary landing site will be identified in mid-September, with a detailed analysis of possible flight paths then carried out, before a final decision is made to go ahead and prepare for landing, currently planned for 11 November.