A microbiologist collects a swab sample from the floor of a spacecraft assembly clean room at NASA's Jet Propulsion Laboratory where samples such as this are taken frequently during the assembly of a spacecraft and analyzed.

A microbiologist collects a swab sample from the floor of a spacecraft assembly clean room at NASA's Jet Propulsion Laboratory. Samples such as this are taken frequently during the assembly of a spacecraft and analyzed for a census of the types and numbers of microbes present in the clean room.

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