If that were the case they would probably be showing it off instead of hiding it....most people don't even know it exists.
My guess is long term testing of SLS/ORION systems and components as well as space warfare and defense weaponry....perhaps even particle beam tech.
Probably research. Its bringing stuff back, so likely its testing exposure of *something(s)* to conditions in space. Being a DARPA program, I doubt its anything meant to benefit you and I, but rather the technological elite breakaway civilization that developes and hordes 'disruptive' technologies.