Digital Beamforming has gained significant importance in radar applications in the past years. It helps improve radar performance while reducing mass and power. Improving these figures becomes even more important for space applications. The Space Exploration Synthetic Aperture Radar (SESAR) is a novel P-band (70 cm wavelength) radar instrument developed for planetary applications that will enable surface and near-subsurface measurements of Solar System planetary bodies. The radar will measure full polarimetry at meter-scale resolution, and perform beam steering through programmable digital beamforming architecture. The data obtained with SESAR will provide key information on buried ice and water signatures that can facilitate the design of future human and robotic exploration missions. In this paper we describe SESAR's large antenna array, the sub-systems integration process, and the different environmental testing activities performed to the overall system in order to raise the Technology Readiness Level (TRL) for its future inclusion in a space-proven system.