Sounds like a lot of responsibility, Doc. Does he protect the planet from domestic threats or foreign ones?
She, actually. And the answer is 'both'.
Discovered during the Challenger tragedy that life forms (aboard the shuttle) could fall from space, burn in the atmosphere, and survive a plunge to the planet's surface still alive. (worms, bacteria, etc.)
Now concerned about bacteriological contamination on space probes sent to places such as Mars or Europa. Probe lands. Sensors detect bacteriological life forms. Did they arrive piggybacking on the probe?? Bummer if they did... the scientific value is lessened and we contaminated some alien environment.
OTOH, we brought moon rocks back from the moon. Didn't know that (theoretically) life forms could have come back with them. Same thing with future material returned from wherever. Bummer if they bring back something unwanted. The results could be interesting...
At the moment the job basically entails ensuring that probes sent to the surface of Mars or other locations are sterile.
Bill Stone's robot is slated to go to Europa, one of the moons of Jupiter, to look for life forms in the (H2O ocean) beneath the ice crust. Hence her concern in (1) making sure it works; and (2) making sure it can be sterilized.......