Obtaining Color Television Pictures from Space

When using a TV system it is desirable to be able to measure selfluminous and non-selfluminous objects, so that the attribute of their appearance known as color can be expressed numerically. Being able to determine the spectral reflectance curve of a rock or other substance on another planet would be very helpful in identifying the material. Surveyor spacecraft, which soft-landed on the lunar surface from 1966 through 1968, have slow-scan 600-line TV systems utilizing a mirror, variable focal-length lens, vidicon tube and a rotating color wheel which holds three primary color filters. The color filters were designed to rotate individually into the optical path of the camera, which necessitated three identical photos being taken, one photo using each of the three color filters. The TV-camera electronics relative-spectral response had to be found before the desired spectral transmittance of the three color filters could be selected. Moreover, the green response had to match the corresponding CIE standard tristimulus value curve because the green response is the basis for defining the photometric unit of luminous flux. Typical color results are discussed.

Print ISSN

0361-4573

Published

1968-09

Content type

Original Research

DOI

10.5594/J16730