[@Eviledd1984] You're not on this planet to find Samus.  You're on this planet to see where Samus [i]went[/i].  Additionally, Zen will weigh in - since this is approximating the discussion on the way - that he is the only one who is not at risk of infection, so he is the only one that can be safely separate from the group at extended periods of time.  Cassius is the one equipped to perform extra quarantine field work.  This cannot be performed if you're a long way away.  Everyone else may find ways to recharge field units for themselves, but they cannot do what the support guy does.  They specialize in other fields of research and defense.