Strange Comet Unlike Anything Known

[On the Road]

The comet, examined in a close flyby in January by NASA's Stardust spacecraft, has towering protrusions and steep-walled craters that seem to defy gravity. More than a dozen jets of material shoot out from its insides. Dust swirls around the comet in unexpectedly dense pockets.

Among the bizarre features are two depressions with flat floors and nearly vertical walls that resemble giant footprints. They aren't structured like typical impact craters. The features have been named Left Foot and Right Foot in a new map of the comet, which is roughly 3 miles (5 kilometers) wide.

---snip

"Comets do blow up unexpectedly," Brownlee pointed out, adding that built-up internal pressure and "steam explosions" might be responsible for some of the surface features.

In another baffling surprise, Brownlee said, dozens of photos show no small craters on Wild 2, only the large craters that are presumably billions of years old. Perhaps small craters erode away, he said.




http://www.space.com/scienceastronomy/stardust_results_040617.html

[Gman]

1. Interesting

I could write many paragraphs about why I think these conditions exist on this comet. But, I think I can probably safely say we'll eventually find out that no two are alike.

More than anything else, I'm amazed that we can actually map the surface of a comet, arguably the most mysterious object in space.

[On the Road]

3. The Link Actually Has a Video Clip of the Flyby

jerky but still impressive.

Another trend I noticed that's also being done on the Mars landers is to use experimental procedures to check out hypotheses. In the case of the Wild comet, they constructed a surface of frozen ice and organic (carbon-based) material and shot pellets at it to try to simulate the unusual crater shapes. The result was remarkably similar to the Wilt comet:


A 0.13-inch (3.2-mm) projectile created this 4-inch (10-cm) crater with a flat floor and sheer walls in lab material perhaps similar to the composition of comet Wild 2.

[Dogmudgeon]

2. Wild, Baby, Wild!

--bkl