We develop a model for a large array ground receiver system for use in deep space communications, and analyze the resulting array channel capacity. The model includes effects of array geometry, time-dependent spacecraft orbital trajectory, point and extended interference sources, and elevation- dependent noise and atmospheric channel variations. Channel capacity is expressed as a simple quadratic form dependent upon covariance matrices characterizing the source, interference, and additive noise. This formulation facilitates inclusion of array and channel characteristics into the model, as well as comparison of optimal, suboptimal and equivalent single-antenna configurations on achievable throughput. Realistic examples of ground array channel capacity calculations are presented, demonstrating the impact of array geometry, planetary interference sources, and array combining algorithm design upon the achievable data throughput.