Proteus
Scaled Composites Proteus

The Far Infrared Sensor for Cirrus (FIRSC) is a remote passive airborne infrared spectrometer that uses Fourier transform spectroscopy (FTS) to measure the infrared radiance of cirrus clouds. FIRSC operates across two channels with a wavenumber range of 10-35 per centimeter and 80-135 per centimeter. It has a field of view of 0.03 radians, a footprint of less than one kilometer, and a scan time of 4 seconds.

The NPOESS Aircraft Sounder Testbed - Microwave (NAST-M) is an airborne microwave radiometer operated by the Massachusetts Institute of Technology (MIT). It measures brightness temperature, which can be used to retrieve water vapor profiles in the atmosphere. It consists of two radiometers: one operating across eight channels between 50-57 GHz and the other across nine at 118 GHz. In 2003, NAST-M was upgraded with two additional radiometers at 183 and 425 GHz to enhance water vapor retrievals and detect small hydrometeors. NAST-M has a spatial resolution of 2.6 km and a cross-track swath width of 100 km at a flight altitude of 20 km. Its typical integration time is 100 ms.

The NPOESS Aircraft Sounder Testbed - Interferometer (NAST-I) is an airborne infrared interferometer operated and maintained by NASA Langley Research Center (LaRC). It uses Fourier transform spectroscopy to measure brightness temperature and radiance. NAST-I operates within the spectral range of 3.7-16.1 µm and has a spectral resolution of 0.25 cm-1. It features a spatial resolution of 2.6 km and a cross-track swath width of 46 km at a flight altitude of 20 km. A complete scan cycle for NAST-I takes approximately 12.2 seconds.