QUESTION:
While watching pre-launch pictures, technicians appear dressed in isolation
suits. Why?

ANSWER from Rob Manning:
Technicians and engineers that work in the vicinity of the lander must wear
what we call "bunny" suits (it was a joke name originally, but many years
ago the name caught on). These are clean head-to-toe garments that prevent
dirt and biological contamination of the lander by the workers.

At other times when the hydrazine fuel was being loaded into Pathfinder's
fuel tanks, some workers had to wear "SCAPE" suits. These suits are also
head-to-toe, but they also provide self-contained breathing equipment which
is strapped to their backs. In fact they look a lot like space suits.
Hydrazine, in addition to being highly flammable, is an extremely caustic
and dangerous liquid. These suits are designed to protect the workers in the
unlikely event of a hydrazine leak.

--Rob Manning