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The changing surface of Comet 67P/C-G

Changes on Comet 67P/C-G after outburst

More results from this week’s 50th Lunar and Planetary Science Conference in Texas! Two presentations today focused on showing the dramatic changes on the surface of Comet 67P/C-G that were documented by Rosetta. The first focused on the changes produced after massive outbursts during the comet’s closest approach to the Sun. The second documented several more evolutionary changes that changed more slowly.

The image to the right comes from the first paper, and shows the changes that took place on the surface following one massive outburst, with the numbers in red indicating unchanged features between the two photographs.

It appears an entire cliff section has disappeared, replaced by a single large giant boulder. Interestingly there is no obvious vent opening for the outburst. Instead, it appears that the eruption occurred below ground, and merely blasted part of the surface into space. As noted in the paper:

We report here on a third cliff collapse that occurred in the southern hemisphere in the Sobek region [7], which corresponds to the neck region in the 67P’s southern hemisphere. Due to the close alignment of the 67P’s
southern summer solstice with perihelion passage, the southern hemisphere is subjected to higher solar input, resulting in higher levels of activity and more intensive erosion. The location of the collapsing cliff in Sobek is consistent with the inferred source region of one of the strong outbursts [previously reported].

The paper also showed evidence of a large boulder more than a 100 feet across moving several hundred feet over a period of seven months.

The second paper showed various changes in a number of depressions and scarps on the smooth flat surfaces near the narrow neck that connected the comet’s two lobes. Examples of this terrain can be seen in high resolution pictures here and here and here and here.

From this data scientist suggest that the neck region is slowly dissolving away, its material in these flat areas flying away because the neck happens to be a region of low gravity.

Pioneer cover

From the press release: From the moment he is handed a possibility of making the first alien contact, Saunders Maxwell decides he will do it, even if doing so takes him through hell and back.

 
Unfortunately, that is exactly where that journey takes him.

The vision that Zimmerman paints of vibrant human colonies on the Moon, Mars, the asteroids, and beyond, indomitably fighting the harsh lifeless environment of space to build new societies, captures perfectly the emerging space race we see today.

He also captures in Pioneer the heart of the human spirit, willing to push forward no matter the odds, no matter the cost. It is that spirit that will make the exploration of the heavens possible, forever, into the never-ending future.

Available everywhere for $3.99 (before discount) at amazon, Barnes & Noble, all ebook vendors, or direct from the ebook publisher, ebookit. And if you buy it from ebookit you don't support the big tech companies and I get a bigger cut much sooner.

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