1
Aug
2014

Rosetta update Aug. 1: Comet 67P/C-G’s pitted surface

July 31 photo of Comet 67P/Churyumov-Gerasimenko shows lots of shallow depressions and two curious bright spots. The comet is 2.5 miles (4 km) across. Credits: ESA/Rosetta/NAVCAM

In case you couldn’t tell, I’m kind of excited about the Rosetta mission to Comet 67P/Churyumov-Gerasimenko. Today, the European Space Agency published a fresh, more detailed photo taken on July 31. Notice how rugged the comet’s surface looks. Right away I thought of another comet with a similar appearance, 81P/Wild.

Comet 81P/Wild 2 photographed during the Stardust mission in 2004. Wild 2 measures 1.03 x 1.24 x 1.71 miles and goes around the sun once every 6.4 years. Its surfaced is riddled with flat-bottomed craters, some of which may also be gas vents from vaporized ice. Credit: NASA

NASA flew the Stardust spacecraft past the comet in January 2004, took photos and measurements and collected particles from 81P’s coma that were later returned to Earth for study. If you compare the photos, both show lots of shallow depressions.

It’s speculation only, but there appear to be two small hills, large boulders or even spires near the top of 67P’s smaller lobe. Studying the photo closely, the direction of sunlight is from the bottom up . Whatever the two bright dots are, they rise above the general landscape because they cast clear shadows. The lower rims of several of the comet’s ‘craters’ are rimmed with shadow as well.

Just a caution – I could be wrong about this interpretation. The little hills or whatever they are may be little more than image artifacts.

Either way, looking at the photo makes me feel like I need a new glasses prescription. So much detail is tantalizingly close to coming into clear focus. We’re not quite there yet.

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