So few people do favors for NASA these days. So when Jeff Bezos, the Amazon.com founder, announced last week that an expedition he financed had hoisted two F-1 rocket engines from an Apollo mission off the ocean floor, the agency was understandably grateful.

“We look forward to the restoration of these engines by the Bezos team and applaud Jeff’s desire to make these historic artifacts available for public display,” the NASA administrator, Maj. Gen. Charles F. Bolden Jr., said in a statement.

The engines may have been among the five that helped launch Neil Armstrong and his Apollo 11 shipmates to the Moon in 1969, while Mr. Bezos, then 5, watched on television. Today Mr. Bezos, one of a lineup of millionaires keen on space and underwater adventure, noted in a blog post that the F-1 rocket engine is “still a modern wonder — one and a half million pounds of thrust, 32 million horsepower, and burning 6,000 pounds of rocket grade kerosene and liquid oxygen every second.”...