NASA is investigating the use of swarms of robotic vehicles for future space exploration missions. Such swarms offer many advantages of traditional, single spacecraft, missions. Intelligent swarms offer potential for selfmanagement and survivability, and their emergent properties make such swarms potentially very powerful. However, they are signi.cantly more dif.cult to design, and ensuring that proper behaviors will emerge is a complex task. NASA?s FAST project is investigating the use of formal approaches to the speci.cation and veri.cation of such systems. Using ANTS, a NASA concept mission, as a case study, multiple formal methods were evaluated to determine their effectiveness in modeling and ensuring desired swarm behavior. We discuss this evaluation and propose a hybrid formal method for use in the development of future NASA intelligent swarms.