Speaking of Jets, Scientists are quite sure the jets are due to sub-surface sublimation of volatiles (water, HCN etc.) forcing out dust particles at the same time. Surfaces appear quite stable, and the jets are in static positions on the comet nucleus.
The following link for comet temple 1 demonstrates how jets on the same location of the comet sporadically ejects a sudden large amount of mass, at the same point of its 44 hour rotation period - ie. in the same direction in space. Scientists believe this is due to the uneven solar related heating related to the rotation somehow causing the random outburst. It would be a better science fiction story if these jets were an orbit correction maneuvre.
Scientific theory holds that many comets are loosely connected pieces given the long List of comet pairs and other splitting events that have been shown to occur.
It would be a much better science fiction story if these events were like amoebal fission - ie. that comets were reproducing. They may have been around for many millions of years, accreting mass through collisions. Now they have enough energy and mass that they can reproduce and go their separate ways - perhaps one might one day leave the solar system and explore other systems.