Armstrong’s soil also contained hydrogen, helium, nitrogen and carbon, much of which had been deposited by the solar wind, the stream of high-speed particles continually flying outward from the sun. A light version of helium, helium-3, is of particular future interest as fuel for fusion reactors, which could generate bountiful, nearly clean energy by combining atoms.

“It told us there were going to be tremendous amounts of potential resources for use in space, and possibly even on Earth,” Dr. Schmitt said.

Another far-reaching scientific legacy of the moon rocks gathered by the Apollo astronauts is how scientists used them to calibrate a technique of using craters to determine the ages of places in the solar system.

The concept is simple. Over time, impacts of asteroids, big and small, pocked the surface of the moon and elsewhere. But a layer of ice or lava can erase the craters and reset the clock. Thus, a heavily cratered surface is older than a smooth one. But while planetary scientists could see which places were older and which were younger, they did not know exactly how old any of them were.

With the dating of the rocks taken from Apollo 11’s landing site, scientists then knew the age of that patch of the lunar surface. Rocks from the other five Apollo landings set the ages of those corresponding regions, which then correlated with the different numbers of craters in each place.