Dr. John Charles spent nearly 33 years at NASA—most recently as Chief Scientist of the Human Research Program—working on human spaceflight through Shuttle, Mir, ISS, and beyond. He lead missions such as STS-95 (John Glenn’s Shuttle flight), STS-107, and the Twins Study with Scott and Mark Kelly. He retired from NASA in February 2018 and is now the Scientist in Resident at Space Center Houston. We talk about his career, the human spaceflight issues he worked and solved in his time at NASA, and the things that need to be solved for the exploration of the Moon, Mars, and beyond.

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