Why are bacteria that survive the clean room environment considered prime candidates for surviving a journey through space?

Answer

They are already adapted to rigorous, dry, and often chemically treated environments.

The bacteria thriving in the clean room setting have already demonstrated an aptitude for surviving environments engineered by humans to be hostile, mirroring some aspects of the extreme conditions found off-world.

Why are bacteria that survive the clean room environment considered prime candidates for surviving a journey through space?
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