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Sunday, August 23, 2015

Gravity, Part 2

Watched Gravity (Warning: autoplay) again last night. It was just as great as the first time, partly because my memory was playing tricks on me. I distinctly remember Kowalski telling Ryan to open the oxygen valves on the Soyuz spacecraft, but he didn't.

Gravity - Clip (9/11): Shenzhou Re-entry
     Since I have been mulling over reentry I paid a little more attention to this sequence. Notice that the capsule is tumbling when it begins reentry, but after it separates from the attached modules, it straightens out and flies right. Posting a question on the reference desk led to Wikipedia's article on Atmospheric entry, where in I found this bit:
The Apollo Command/Service Module used a spherical section forebody heatshield with a converging conical afterbody. It flew a lifting entry with a hypersonic trim angle of attack of −27° (0° is blunt-end first) to yield an average L/D (lift-to-drag ratio) of 0.368.[10] This angle of attack was achieved by precisely offsetting the vehicle's center of mass from its axis of symmetry. 

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