Deep Impact followup
Jul. 16th, 2005 09:12 am![[personal profile]](https://www.dreamwidth.org/img/silk/identity/user.png){kind=small}
mmcirvinOne of the stated goals of the Deep Impact mission was to punch through the upper, dustier layers of the comet to expose pristine water ice in the interior. It now appears that this didn't happen: the impact mostly threw up dust from an unexpectedly thick layer poor in volatiles, which is probably why the impact ejecta appeared brighter than expected.
For some of the scientists on the project this has to be disappointing, but it's interesting in itself, since the theory of the internal composition of comets like Tempel 1 is going to have to be revised. Tempel 1 is a periodic comet that's been orbiting more or less in the inner solar system for a long time, but it isn't quite right to just say that it's deader than expected, since astronomers already knew exactly how active it is (and plenty of jets and such have been seen in the intensive observations before and after the impact). Apparently the volatiles are further down and the boiled-out crust thicker than previous theory stated. There's also the mystery of why it looks so different from Comet Borrelly, which was photographed by the Deep Space 1 ion-drive test spacecraft; as far as anyone knew, Borrelly and Tempel 1 ought to have been similar objects.
For some of the scientists on the project this has to be disappointing, but it's interesting in itself, since the theory of the internal composition of comets like Tempel 1 is going to have to be revised. Tempel 1 is a periodic comet that's been orbiting more or less in the inner solar system for a long time, but it isn't quite right to just say that it's deader than expected, since astronomers already knew exactly how active it is (and plenty of jets and such have been seen in the intensive observations before and after the impact). Apparently the volatiles are further down and the boiled-out crust thicker than previous theory stated. There's also the mystery of why it looks so different from Comet Borrelly, which was photographed by the Deep Space 1 ion-drive test spacecraft; as far as anyone knew, Borrelly and Tempel 1 ought to have been similar objects.