"The altitude for the heart and lungs is not a problem for the horses, " said vet Annina Widmer.

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Researchers at the Massachusetts Institute of Technology and Cambridge University have estimated the impact on the ground of emissions from aircraft flying at cruise altitude (about 35, 000 feet), a problem typically ignored by regulations.

ECONOMIST: Planes and pollution

Engineers and mission control officials worked to quickly identify and fix the problem, before Dragon started tumbling or even losing altitude.

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When it's depressurized at altitude, it becomes a near-vacuum, causing the aforementioned heat-transfer problem.

ENGADGET: Art Thompson, Red Bull Stratos' technical project director, talks circuit breakers, wind shear and biomedical data