Microbiological burden on the surfaces of Explorer 33 spacecraft.

The Explorer XXXIII Spacecraft (Anchored Interplanetary Monitoring Platform, or AIMP) was decontaminated to prevent gross contamination of the moon with terrestrial microorganisms. Assay of the total spacecraft surface before and after decontamination showed that the decontamination procedure reduced the viable microbiological burden from 1.40 x 10(6) to 3.60 x 10(4). However, assembly of parts which were not decontaminated for engineering reasons or were not assembled under cleanroom conditions increased the viable microbial burden at the time of launch to 2.62 x 10(5).