This thesis discusses the ongoing development of large format 2k x 2k pixel 10 μm cutoff wavelength HgCdTe detector arrays for low background space applications. This collaboration among Teledyne Imaging Sensors (TIS), University of Rochester, and NASA JPL seeks to determine the performance of the latest arrays that were produced by TIS for the NEOCam space mission, and characterize the image quality. Analysis of the dark current mechanisms of one array shows that these detector arrays are limited by thermal diffusion current down to ~ 42 K, have some contribution of thermal G-R current down to 41 K, then limited by a 0.2 e^-/s light leak in our dewar. The trap-to-band tunneling current that has been the limiting mechanism for a previous generation of detectors is not significant at the applied reverse bias required by NEOCam. In order to demonstrate the ability of these detectors to operate in a space-like environment, proton testing was conducted at the University of California Davis Crocker Nuclear Laboratory. During proton irradiation, the 1k x 1k detector array whose substrate thickness is now the baseline had no measurable substrate luminescence, and the pixels that were hit by a proton recovered after reset. The total operability decreased by a few percent after a cumulative lifetime dose of irradiation, but was still above the NEOCam requirement of > 90%. We also assessed the temperature stability and found that the noise measured while the temperature is fluctuating ± 50 mK was the same as measured at a constant temperature. Finally in order to assess the probable image quality, we measured the MTF and the effect of residual images.