More Chang'E 2 Toutatis flyby images
Posted By Emily Lakdawalla
2013/01/20 09:52 CST
Last week at a meeting of NASA's Small Bodies Assessment Group (SBAG), Han Li of the Chinese Academy of Sciences gave a lengthy presentation on Chang'E 2. Much of the presentation focused on the mission's work at the Moon, but at the end she spent several slides discussing the Toutatis flyby. Her slides are posted here, and they include, on slide 76, eleven images from the flyby. The closest three are truncated, but not for the usual reason (the usual reason being that the target was out of the frame). They're truncated because they're occulted by the solar panel, which makes sense, because this was a solar-panel-monitoring engineering camera.
Compared to the previously published set of images (which I'm including below for comparison), this set is of lower quality, I presume because it was embedded within a PDF file and the image quality was reduced during saving.
It didn't take long for Daniel Macháček to combine the truncated images with the best full-disk (if you can call it a disk) image from the previous set, making the best-yet composite view of the asteroid:
Another notable difference in the new set of images is the metadata -- there's been a revision of the ranges and times reported for each image. The range, Li reported, is based upon inspection of the images rather than tracking data, so revision of the range is not surprising. But I'm a little befuddled by why the times would need to be changed by several seconds. I thought that maybe these were spacecraft time and the previous ones Earth-received time, but the difference is not large enough for that; Chang'E 2 was 7 million kilometers from Earth during the encounter, about 25 light-seconds one-way.