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   Our goals are to place an upper limit on the density of matter in the
   universe and to study the evolution of clusters of galaxies. We wish to
   measure the temp- eratures and possibly the iron abundances (Fe/H) of a
   complete sample of clusters of galaxies spanning the redshift range
   between z=0.3-0.9. To accomplish our goals, we need only to observe a
   single cluster of galaxies, MS0302+1717, to complete the observations
   of all of the EMSS clusters of galaxies with z>0.3 and Fx > 2.0e-13
   erg/s/cm2. We will use maximum likelihood statistics to compare the
   observed distribution of cluster temperatures and redshifts to that
   predicted by theoretical models. With ASCA spectra and ROSAT HRI
   images, we will also compare the X-ray-determined total mass of
   MS0302+1717 to its lensing mass.
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