 This was attributed by NASA to the camera not being sterilized on Earth prior to its launch two and a half years previously..However, later study showed that the scientists analysing the camera on return to Earth used procedures that were inadequate to prevent recontamination after return to Earth, for instance with their arms exposed, not covering their entire bodies as modern scientists would do.There may also have been possibilities for contamination during the return mission as the camera was returned in a porous bag rather than the airtight containers used for lunar sample return.