Aug 03 2015

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Where is Philae? (Part a hundred)

Philae results shed light on the nature of comets. This follows up on the article linked in an earlier post, providing more details on the data they were able to collect on Philae’s multi-touchdown landing.

It has this picture:

Now, we finally know where Philae approximately (probably within 10 meters). In the earlier post, I said I didn’t anticipate the sharp angle that Philae took after it’s first bounce, but looking at the image above, I believe that the vector is still straight, and that the sharp angle indicated is really just showing the curvature of the “duck head” of the comet.

Assuming that’s the case, I’ve taken my original estimate of 1535 meters, the note from the previous post that it looks like my original vector was about 10 degrees eastward of the actual direction that Philae landed, and projected the landing point that I predicted right after touchdown.

Philae estimated landing spot

Again I say: not bad for an initial, back-of-the-envelope guess back in November.

Other findings reported in the article:

  • Philae’s original landing site was covered by only about 9 inches of dust over bedrock, which is why it couldn’t anchor itself.
  • The final landing spot was more than twice as hard as the first spot — way harder than anticipated and likely why Philae couldn’t anchor itself well in its final landing spot.
  • “67P has dust/ice ratio of 0.4 to 2.6 and a very high porosity of 75 to 85%”
  • Philae detected 16 organic compounds during its decent and landing, 4 of which (methyl isocyanate, acetone, propionaldehyde, and acetamide) were not known to exist on comets.
  • 67P has a radiation-induced polymer on it, which is weird…but perhaps exciting from an ISRU standpoint.

Permanent link to this article: http://www.newspaceraces.com/2015/08/03/where-is-philae-part-a-hundred/

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