  We examine the constraints that satellite-acquired Type Ia and IIP supernova
apparent magnitude versus redshift data will place on cosmological model
parameters in models with and without a constant or time-variable cosmological
constant $\Lambda$. High-quality data which could be acquired in the near
future will result in tight constraints on these parameters. For example, if
all other parameters of a spatially-flat model with a constant $\Lambda$ are
known, the supernova data should constrain the non-relativistic matter density
parameter $\Omega_0$ to better than 1% (2%, 0.5%) at 1$\sigma$ with neutral
(worst case, best case) assumptions about data quality.
