Moon rocks NASA collected during its six moon landings in the early 1970's have gone missing from the space agency, and a recent internal audit shows more than 500 samples are now unaccounted for. Apollo astronauts brought back 812 lbs of lunar rock and dust staring with the 1969 Apollo 11 landing of the first men on the moon's surface, and NASA has loaned out thousands of samples over the years for study.

"(NASA) lacks sufficient controls over its loans of moon rocks and other astromaterials, which increases the risk that these unique resources may be lost," Paul K. Martin, NASA Inspector General wrote in a report released Dec. 8.

"NASA has been experiencing loss of astromaterials since lunar samples were first returned by Apollo missions," he said.

Martin's office audited 59 people who had gotten NASA samples, and found that 11 of them, did not know where all of the material was. Additionally, Martin found the Astromaterials Acquisition and Curation Office at the Johnson Space Center in Houston had records of hundreds of samples that no longer exist, and loans to a dozen people who had died or retired without returning them.

"The Curation Office did not ensure that these loaned research samples were efficiently used and promptly returned to NASA," Martin wrote. "For example, we learned of one researcher who still had lunar samples he had borrowed 35 years ago on which he had never conducted research."

Overall, NASA maintains a huge inventory of space stuff, and regularly loans out not only moon rocks, but meteorites and cosmic dust to institutions and educators.

"NASA is committed to the protection of our nation's space-related artifacts, and sharing these treasures with outside researchers and the general public," NASA spokesman Dwayne Brown said in a statement. "We agree with the recommendations contained in the recently released Inspector General report examining NASA's controls over loans of moon rocks and other astromaterials to researchers and educators. Actions will mostly result in changes to loan agreements and inventory control procedures."