Of all the six mission, the Apollo 11 mission got back only 22 kilograms of moon rocks, the least amount of samples.
The rocks were gifted to all existing nations at that time and have since been lost to time, destroyed or stolen.
To get grams of these precious samples on Earth, scientists go through a rigorous process when requesting a sample.
The samples were vacuum-sealed on the Moon & brought to Earth by Apollo 17 astronauts 50 years ago.
Of the Apollo 11 rocks given to other countries, about 70% remain unaccounted for, he said.