Astronauts Neil Armstrong and Buzz Aldrin were able to secure lunar samples from the surface of the moon from the Apollo 11 mission and bring them back to Earth.
However, in order to ensure that it was safe to store lunar samples on Earth, scientists had to run a number of tests to make sure contamination was not possible, according to NASA.
"We had to prove that we weren't going to contaminate not only human beings, but we weren't going to contaminate fish and birds and animals and plants and you name it," said Charles Berry, head of medical operations during Apollo, in an oral history.
"They didn't find any microbial growth on the lunar samples, and they didn't have any microorganisms that they at least initially attributed to any extraterrestrial source or lunar source," said Hayes.
It wasn't until after the Apollo 14 mission in 1971 that NASA felt it was safe enough to stop testing on animals and to end the quarantine process for astronauts and lab technicians working with any lunar samples.