Title: Compact Fire Infrared Radiance Spectral Tracker (c-FIRST)
Presenting Author: Sarath Gunapala
Organization: NASA Jet Propulsion Laboratory
Co-Author(s): William Johnson, Alexander Soibel, David Ting, Perry Ramsey, Olga Kalashnikova, Michael Garay, Ashley Davies, Yuki Maruyama, Sir Rafol, Ashok Sood, John Zeller, Christopher David, Sachidananda Babu, and Parminder Ghuman

Abstract:
Remote sensing and characterization of high temperature targets on the Earth’s surface is required for many cross-disciplinary science investigations and applications including wildland fire impacts on ecology, the carbon cycle, and atmospheric composition. For decades this research has been hindered by insufficient spatial resolution and/or detector saturation of satellite sensors operating at short and mid-infrared wavelengths (1-5 μm) where the spectral radiance from high temperature (>800 K) surfaces is most significant. To address this critical need, we are developing a compact modular high dynamic range multispectral imager. The goal of this IIP-21 funded project is to demonstrate this novel technology through the maturation of a mid-wavelength infrared (MWIR) imager, the Compact Fire Infrared Radiance Spectral Tracker (c-FIRST), which leverages digital focal plane array (DFPA) technology. The DFPA is hybridized from a state-of-the-art high operating temperature barrier infrared detector (HOT-BIRD) and a digital readout integrated circuit (D-ROIC), which features an in-pixel digital counter to prevent current saturation, and thereby provides very high dynamic range (>100 dB). The DFPA will thus enable unsaturated, high-resolution imaging and quantitative retrievals of targets with a large variation in temperatures, ranging from 300 K (background) to >1600 K (hot flaming fires). With the resolution to resolve 50 m-scale thermal features on the Earth’s surface from a nominal orbital altitude of 500 km, the full temperature and area distribution of fires and active volcanic eruptions and the cool background are captured in a single observation, increasing science content per returned byte. We just completed the preliminary integration of the c-FIRST optics chamber and the optical components. The full c-FIRST instrument integration will be completed at the end on second quarter of 2024 in preparation for the airborne test during the 2024 fire season (August – September) in western United States.