VLWIR Sensors for Detecting and Tracking Near-Earth Asteroids

An important NASA mission is to detect, count and track near-earth asteroids for a variety of reasons including the hazards of collisions with our planet. Such asteroids are mostly dark, small and cold (~ 200K); so they are best detected in the very longwave infrared (VLWIR) wavelengths greater than ~ 12 microns where they glow brightest. To accomplish this, we developed in Phase I a record-performing focal plane array (FPA) of antimony-based strained layer superlattices (SLS) with cutoff wavelength = 13.5 microns, quantum efficiency = 30-50% in the 3.0-13.5 micron spectral band, dark current = 1/4th that of incumbent mercury cadmium telluride (MCT) per Rule07, and operating with background-limited-performance (BLIP) at 75K with superb array uniformity, operability and image stability. In Phase II, we propose to increase array format to 1024x1024, integrate the FPA with three spectral filters (one fire channel and two thermal channels), and package it into a compact camera. The camera will be delivered to NASA for evaluation for missions like Landsat Data Continuity Mission - Thermal Infrared Sensor (LDCM-TIRS), where it will offer greater ground resolution in a small, lightweight, low-power package. More »