Enabling the NASA decadal-survey “PATH” mission

In its “Decadal Survey” of earth science missions for NASA published in 2007 [1] the U.S. National Research Council (NRC) recommended that a geostationary microwave sounder be developed for a Precipitation and All-weather Temperature and Humidity (PATH) mission and recommended that it be implemented as an “array spectrometer”. That was largely based on a synthetic-aperture concept then under development at the Jet Propulsion Laboratory (JPL). At the time the required technology was not perceived as being sufficiently mature, and PATH was therefore put in the “third tier” group of missions. Now, under the NASA Earth Science Technology Office's (ESTO) Instrument Incubator Program (IIP), the key technology has been developed and has been brought to Technology Readiness Level (TRL) 6, required for mission implementation, thus enabling the PATH mission.