Decelerating and Dustfree: Efficient Dark Energy Studies with
Supernovae and Clusters

The key issues needing to be addressed for next generation studies of
dark energy and cosmology are observations at high redshifts and with
robust systematics control.  We propose novel techniques for achieving
both simultaneously, eliminating difficulties in the use of GOODS data.
By targeting massive galaxy clusters at z > 1 we obtain a high
efficiency in detection of Type Ia supernovae, minimization of the
dominant systematic of host galaxy extinction using cluster ellipticals,
and we leverage cluster studies through weak lensing, optical, X-ray, and
Sunyaev-Zel'dovich measurements.  The data will set the stage for
improvement of (unbiased) supernova constraints on dark energy time
variation by a factor two, and serve as a bedrock scientific resource
for cluster studies.