Emily LakdawallaNov 04, 2010

Hartley 2's jets

It was a very happy set of scientists, engineers, managers, and administrators who filled the Jet Propulsion Laboratory's Von Karman auditorium this afternoon to do the postgame show on Deep Impact's flyby of Hartley 2. Project Manager Tim Larson remarked that the spacecraft and its navigators could not have performed better; the aimpoint for the flyby was missed by only two seconds in time and three kilometers in distance, which is pretty darned close to the mark. And of course, the images, as I mentioned previously, were spectacular.

I won't have time this afternoon to post a detailed writeup about the press briefing -- look for that tomorrow -- but I thought I'd post just one image from the briefing, the one that got a big "ooooh!" from the auditorium. It was part of co-investigator Jessica Sunshine's presentation on the appearance of the comet nucleus. It's an enhanced view of the part of the comet that is notdirectly lit by the Sun -- that is, the comet's night side, and the terminator (the day-night boundary).

Nightside jets on Hartley 2
Nightside jets on Hartley 2 Hartley 2 is an unusually active small comet, a fact made clear by this enhanced view of its night side captured by Deep Impact near its closest approach on November 4, 2010.Image: NASA / JPL / UMD

There are so many amazing things about this one photo. It's amazing how many jets there are. It is amazing that you can track the jets right down to where they are erupting from the sunlit surface. It is amazing that there are so many jets on the night side -- comets aren't supposed to do that. The nightside jets are not visible where they sprout from the surface; that's in the dark. You can see them where the dust from the jets has risen above the nightside shadow, into sunlight. You can even see where there are jets beyond the limb, on the back side of the comet, which, lit up by the Sun, show you where the comet's limb is. It's spectacular.

I'll be back tomorrow with more Hartley 2 awesomeness.

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