An AUV controller must also be extensible to meet the needs of a varied and evolving user community. The range of scientific missions is large, from photography to on-site monitoring to sample collection; not only must the AUV controller be able to handle all these missions, but it should also be able to be easily changed to incorporate new instrument-specific and mission-specific knowledge as needed. In addition, due to the limited knowledge available about the ocean and about controlling AUVs on long missions, it is likely that the AUV's planning knowledge will need to change over time. This can be accomplished by humans or, ideally, by the AUV's mission controller itself as it learns from its experiences.