During Apollo 14 in 1971, command module pilot Stuart Roosa, a former Forest Service smokejumper, carried a canister of roughly 500 tree seeds into lunar orbit at the request of Forest Service chief Edward P. Cliff. Loblolly pine, sycamore, sweetgum, redwood, and Douglas fir seeds were exposed to radiation and microgravity, then germinated at stations in Gulfport, Mississippi and Placerville, California. About 420 seedlings survived, and after more than 40 years of comparison with earthbound controls, scientists found no difference at all, which the episode argues is a reassuring result for future lunar and Martian habitats.

Distributed for the 1976 Bicentennial to the White House, state capitals, universities, and foreign recipients including Emperor Hirohito, the moon trees were then simply forgotten as NASA turned to the Space Shuttle. I ...