Probing Dark Energy with SNAP
  The distance-redshift relation observed for supernovae has led to the discovery that the expansion of the universe is accelerating. A next generation experiment, the Supernova/Acceleration Probe (SNAP), can investigate the nature of the dark energy responsible, determining its energy density contribution and equation of state. In addition, indications of time variation in the equation of state could provide critical clues to the underlying fundamental physics; we show how SNAP can achieve 3 sigma detection of such time variation in some cases. 
Eric V. Linder