CAR

The Cloud Absorption Radiometer (CAR) is an airborne multi-wavelength scanning radiometer that can perform several cloud and surface measurement functions.

The Cloud Absorption Radiometer (CAR), considered the most frequently used airborne instrument built in-house at NASA Goddard Space Flight Center, is capable of measuring scattered light by clouds in fourteen spectral bands. To load an expanded view of the CAR instrument, with many of the mechanical, optical, and electronic components identified, click on the thumbnail image to the right.

The scan mirror, rotating at 100 rpm, directs the light into a Dall-Kirkham telescope where the beam is split into nine paths. Eight light beams pass through beam splitters, dichroics, and lenses to individual detectors (0.34 - 1.27 µm), and finally are registered by eight data channels. They are sampled simultaneously and continuously. The ninth beam passes through a spinning filter wheel to a Stirling cycle cooler. Signals registered by the ninth data channel are selected from among six spectral bands (1.55 - 2.30 µm). The filter wheel can either cycle through all six spectral bands at a prescribed interval (usually changing filters every fifth scan line), or lock onto any one of the six spectral bands and sample it continuously.