The race that catapulted the Cold War into space is long over, with former foes Russia and America now co-habitating in a jointly owned orbital outpost, America's moonwalkers -- those who are still alive -- are now senior citizens, and the moon has remained without new earthly visitors for nearly 30 years.
Yet one legacy of the Apollo program is experiencing a renaissance of sorts, as studies of moon rocks rewrite our understanding of the solar system and our own evolution on Earth.
"We did not go to the moon for science," said Paul Spudis, a geologist and deputy director of the Lunar and Planetary Institute of Houston, "but the Apollo program actually revolutionized science in a way that most people haven't stopped to think about."
The precious Apollo lunar samples are the touchstones for understanding the importance of impacts -- high-speed, massive collisions between planetary bodies that wipe evolutionary slates clean and set the stage for new historical timelines.
To the trained eye and the scientific mind, the moon rocks hold these tales in part because of how Earth's lone satellite came into existence. Current theories -- formed in the wake of Apollo sample analysis -- are based on a hypothesis that a planetary body about the size of Mars smashed into Earth when it was just a baby, a few tens of millions of years old, forming a Saturn-like ring of debris.
The material, along with the remains of the impactor, gradually collected and formed the moon. Because Earth, which is roughly 4.5 billion years old, is geologically much more active than the moon -- with volcanoes, erosion, continental plate motion and other natural phenomena -- the early history of our planet has been erased. The moon, however, inert and unchanging, is locked in time.
"There's a lot of interest lately in the origin of the moon and how it relates to Earth," said NASA's Gary Lofgren, the keeper of the 842 pounds of lunar samples brought back to Earth during the agency's six manned Apollo missions that included lunar landings, the first of which took place on July 20, 1969 -- 33 years ago.
"The lunar collection is still being studied pretty extensively. People are coming up with new and better equipment all the time, so they're able to go back and analyze for things and study problems that they couldn't study several years ago," Lofgren said in an interview with United Press International.
One of the most compelling areas of study involves a period of heavy meteorite bombardment, to which early Earth and its fledgling moon were subjected and which is preserved in the pocked and scarred face of the moon. Earth has no rocks preserved from that early barrage. Later impacts, however, included an asteroid or comet that hit about 65 million years ago and is believed to have changed the planet's climate so swiftly and severely that most life forms came to an end, including the dinosaurs. The age of mammals -- and mankind -- was next to evolve.
"We understand why we're here because we went to the moon," said Spudis. "In my opinion, it is the most profound scientific legacy of Apollo."
Added Lofgren, "Ninety-eight percent of what we know about the moon we wouldn't know if we didn't have the samples. Without them, we would have very limited knowledge."