Infrared Scanning Radiometer

Description

The Apollo 17 IR scanning radiometer experiment will measure, from the orbiting command service module, the thermal emission from the lunar surface in order to obtain a high-resolution surface temperature map. This map will permit calculation of cooling curves for various lunar regions and, hence, the characterization of lunar surface physical parameters such as the thermal conductivity, the bulk density, and the specific heat. In addition, the data will also be used to locate, identify, and study anomalously hot or cold regions at a high spatial resolution over relatively long-term surface cooling periods. Ir data will also be obtained from the far side of the moon for the first time. The radiometer is mounted on the bottom shelf of the scientific instrument module bay and consists of an optical scanning unit and a bolometer with supporting electronics. The optical scanning unit consists of a folded Cassegrain telescope, field-of-view baffles, and a rotating mirror with drive motor and gear bot. The rotating mirror will provide a cross-track scanning capability of 162 deg. The thermistor bolometer is optically linked to a silicon immersion lens. The electronics unit will divide the three scientific temperature telemetry channels into three ranges -- 0 to 160 deg K, 0 to 250 deg K, and 0 to 400 deg K. During operation, these electronics will be clamped once per scan when the radiometer is viewing deep space at the beginning of the scanning cycle. This effect will be estimated during the 60- by 14-n.m. Lunar orbit from succeeding or previous scans because deep space will not be viewed by the radiometer below an altitude of about 40 n.m. A protective cover for the sensor, operated from the command module when required, is provided to protect the optical scanning unit from direct solar illumination and contamination from spacecraft effluent sources.