John C. Houbolt, an engineer whose contributions to the U.S. space program were vital to NASA’s successful moon landing in 1969, has died. He was 95.

As NASA describes on its website, while under pressure during the U.S.-Soviet space race, Houbolt was the catalyst in securing U.S. commitment to the science and engineering theory that eventually carried the Apollo crew to the moon and back safely.

NASA describes “the bold step of skipping proper channels” that Houbolt took by pushing the issue in a private letter in 1961 to an incoming administrator.

“Do we want to go to the moon or not?” Houbolt asks. “...why is a much less grandiose scheme involving rendezvous ostracized or put on the defensive? I fully realize that contacting you in this manner is somewhat unorthodox, but the issues at stake are crucial enough to us all that an unusual course is warranted.”

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