An earth-based, infrared lunar mapper for thermal and composition studies

Equipment was constructed to produce pictorial maps of lunar radiance patterns or of possible variations in lunar surface composition. A motor-driven platform scans a rectangular line raster in the image plane of an astronomical telescope. A liquid helium-cooled copper-doped germanium detector subtending 5 see of arc is scanned through a 15 min of arc square field. The detector signal modulates a glow lamp, also mounted on the scan platform which, by synchronously scanning, builds up a pictorial image on Polaroid film. When operated in the radiometric mode the equipment produces a pictorial display of lunar thermal patterns. When operated in the compositional study mode the incoming lunar emission spectrum is instrumentally compared with the reflection spectrum of mineral specimens. If the spectra are converse the resulting minimum signal produces a dark area on the map, implying compositional similarity between the . lunar surface region and the mineral material. Several pictorial examples are given.