Surveyor 3 - Apollo 12 and The Remote Possibility of Interplanetary Contamination

Apollo 12 and The Remote Possibility of Interplanetary Contamination

The Surveyor 3 landing site was later selected also as the landing target for the Lunar Module of the Apollo 12 manned lunar mission in 1969. Several components of the Surveyor 3 lander were collected and returned to the Earth for study of the long-term exposure effects of the harsh lunar environment on man-made objects and materials. Although space probes have returned to Earth in the decades since Apollo 12, this remains the only occasion in which humans have visited a probe that had been sent to another world.

It is widely claimed that a common type of bacterium, Streptococcus mitis, accidentally contaminated the Surveyor's camera prior to launch, and that the bacteria survived dormant in the harsh lunar environment for two and one-half years, supposedly then to be detected when Apollo 12 brought the Surveyor's camera back to the Earth. This claim has been cited by some as providing credence to the idea of interplanetary panspermia, but more importantly, it led NASA to adopt strict abiotic procedures for space probes to prevent contamination of the planet Mars and other astronomical bodies that are suspected of having conditions possibly suitable for life. Most dramatically, the Galileo space probe was deliberately destroyed at the end of its mission by crashing it into Jupiter, to avoid the possibility of contaminating the Jovian moon Europa with bacteria from Earth.

However, independent investigators have challenged the claim of surviving bacteria on Surveyor 3 on the Moon. (See Reports of Streptococcus mitis on the moon.)