Field Results from the Compact Hyperspectral Air Pollution Sensor–Demonstrator (CHAPS-D)

We present the first laboratory and field results from a prototype small-satellite instrument for targeted trace gas remote sensing. The Compact Hyperspectral Air Pollution Sensor–Demonstrator (CHAPS-D) is akin to TROPOMI and OMI, with unprecedented spatial resolution (1 x 1 km² from low Earth orbit) and the goal of science-quality trace gas measurements. The instrument is a pushbroom spectrometer, measuring solar backscattered radiance at 300–500 nm (@ 0.6-nm spectral resolution). Funded by the NASA Earth Science Technology Office, the miniaturization of CHAPS-D (fits within a 6U CubeSat payload volume) is possible using freeform optics and additive manufacturing. The demonstration reported here comprises a ground-based, zenith-sky test and a series of nadir airborne flights over the Washington, DC/Baltimore metro area using the NASA B200 King Air, achieving an estimated spatial resolution of 20 m. The demonstration includes a simultaneous intercomparison with the co-manifested GeoCAPE Airborne Spectrometer (GCAS). A CHAPS satellite instrument would complement existing and future trace gas surveyors, such as TROPOMI and TEMPO, addressing such issues as the short-term evolution of pollution, turbulent mixing of air pollution plumes, top-down quantification of point-source emissions, and pollution transport and chemical processing.