Opportunities for future supernova studies of cosmic acceleration

We investigate the potential of a future supernova data set. as might be ob tained by the proposed SNAP satellite, to discriminate among different "dar k energy" theories that describe an accelerating Universe. We find that man y such models can be distinguished with a fit to the effective pressure-to- density ratio rr of this energy. More models can be distinguished when the effective slope dw/dz of a changing rt is also fit, but only if our knowled ge of the current mass density Omega (m) is improved. We investigate the us e of "fitting functions" to interpret luminosity distance data from superno va searches.