Thursday, August 14, 2014

Rosetta: Comet probe starts work


A week after arriving at Comet 67P/Churyumov-Gerasimenko, Europe's Rosetta probe is busy acquiring the data needed to select a landing site.


Scientists on the mission expect to meet in just over a week to begin the process of producing a 'long list' of no more than five locations.


These will then be whittled down to two - a primary and a back-up - to be announced in mid-September.


The plan is to try touch down with the piggybacked Philae robot in November.


On Thursday, a new view of the comet from Rosetta's Osiris camera was issued.


It looks across the body of the rubber-duck-shaped object towards its head, revealing new detail of the neck area.



The deep 'gorge' has been measured to be colder than the rest of the comet, suggesting ices may lurk closer to the surface than in other regions so far observed by Rosetta's instruments.


The Max Planck Institute for Solar System Research, which leads the Osiris camera, has put out two very slightly off-set versions on the scene, allowing the viewer to get a 3D impression of the comet when wearing stereoscopic glasses with red-green/blue filters.


The two images used to make this anaglyph were captured 17 minutes apart on 7 August, a day after Rosetta went into 'orbit' around the enigmatic object. The distance is 104km.


'For landing site selection, we must now provide images of course, but also a shape model of the comet, including 3D models of the surface topography,' explained principal investigator Holger Sierks.


'In addition, we'll provide albedo (reflectance) maps, and we can say something about activity levels and surface composition; as well as making obstacle counts - histograms on how many obstacles we see in particular areas,' he told BBC News.


The European Space Agency is now posting an image a day from the navigation cameras on Rosetta.


They do not show as much detail as the Osiris system, but still give fascinating impression of the roughly 4km-wide comet as it turns on its axis - a revolution that takes 12.4 hours.


Below, are the images posted on the Esa Rosetta blog every day over the past week.


Jonathan.Amos-INTERNET@bbc.co.uk and follow me on Twitter: @BBCAmos