Future NASA Earth Science missions require submillimeter-wave remote sensing instruments to monitor air quality, climate variability and change, ozone layer stability, weather, and the global hydrological cycle. A key enabler for this technology is the F-band (106-114 GHz) solid-state power amplifier (SSPA) described in this proposal. This amplifier is need for the LO multiplier chain of the Scanning Microwave Limb Sounder and for the SOFIA (Stratospheric Observatory for Infrared Astronomy) airborne observatory. and other NASA missions. Currently available W/F-band SSPAs simply do not have enough power at this frequency, and further, their efficiency is poor. The efficiency SOA for amplifiers in the adjacent W-band is in the range of 15%, and with practical packaged amplifiers including regulators, the efficiency is often in the single digits. Our approach addresses this need by utilizing high-efficiency wide-bandgap (GaN) device technology and new high-efficiency power combining techniques to reach efficiency levels of 30%. Other NASA applications include LO multiplier chains for THz sensors studying star formation and neutral oxygen (ROSES 2013 APRA proposal). Further, W/F-band FMCW sensors are required for planetary exploration missions to assist in planetary landings. NASA applications require output power levels ranging from less than a watt to perhaps tens of watts at these W/F-band frequencies. Applications for this high-efficiency amplifier technology abound at DoD, but at slightly lower frequencies, primarily the atmospheric window at 94 GHz. These include airborne applications such as helicopter landing and obstacle detection/avoidance radars, very high altitude long duration reconnaissance UAV applications, W-band missile seekers (e.g. AARGM missile) and DoD's W/V-band communications (e.g. Air Forces' WSCE and DARPA's Mobile Hotspots programs). Space-based applications include broadband RF cross-links in satellite constellations, and W-band downlinks for Mobile Hotspots. Specific examples include the Joint Arial Layered Network (JALN), the ICD effort from STRATCOM and AISR. Further, this GaN MMIC technology can be readily applied to other military missions at adjacent frequencies, E and V band. In all these airborne and satellite applications, efficiency is particularly important due to limited availability of prime power. Further, using power combining techniques, this high-efficiency MMIC technology can be extended to applications requiring higher power levels. With the proposed 1-watt MMIC chip as a building block, we can readily extend this technology to applications requiring tens of watts.