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.
We report on the cause and corrective actions of three amplifier crystal fractures in the space-qualified laser systems used in NASA Goddard Space Flight Center’s (GSFC) Ice, Cloud, and Land Elevation Satellite-2 (ICESat-2). The ICESat-2 lasers each contain three end-pumped Nd:YVOO4 amplifier stages. The crystals are clamped between two gold plated copper heat spreaders with an indium foil thermal interface material, and the crystal fractures occurred after multiple years of storage and over a year of operational run-time. The primary contributors are high compressive loading of the NdYVO4 crystals at the beginning of life, a time dependent crystal stress caused by an intermetallic reaction of the gold plating and indium, and slow crack growth resulting in a reduction in crystal strength over time. An updated crystal mounting scheme was designed, analyzed, fabricated and tested. Thee fracture slab failure analysis, finite-element modeling and corrective actions are presented.
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