QUESTION: What do you do to make sure the Hubble doesn't crash into a comet
or any debris in space?

ANSWER from Eric Isaac, Missions Operations, on April 26, 1996

There is not much we could do if a large object such as a comet were on a
collision course with HST.  Fortunately, HST's orbit has thus far proven to
be free from potentially impacting large objects.  However, in the past we
have commanded the HST to take preventative action to avoid impacts from
smaller objects that might be encountered in meteor  showers.  This action
involved placing the -V1 (rear base) of the telescope in the predicted
direction of the oncoming meteor shower in order to protect the critical HST
optics from any damage.  This is sort of like how we turn our backs on a
strong wind since it would likely be less vulnerable to the impacts.