Accession Number : AD0259497

Title :   HORIZON SENSOR PERFORMANCE IN MEASURING ALTITUDE ABOVE THE MOON

Corporate Author : NATIONAL AERONAUTICS AND SPACE ADMINISTRATION WASHINGTON D C

Personal Author(s) : DE FRIES,P.J.

Report Date : JUL 1961

Pagination or Media Count : 1

Abstract : The diameter of the apparent lunar disc can be measured with a horizon sensor. This information may be used by a space vehicle approaching the moon to determine its altitude above the surface. If the lunar radius is not accurately known, an error will result. Also, errors in measuring the chord of the lunar sphere will be caused by the electronic gear and by the uneven features of the moon's surface. In addition, the subvehicle point may lie on an elevation or a depression referenced to the ideal sea level. An error analysis is necessary to determine the usefulness of altitude information obtained by a horizon sensor. (Author)

Descriptors :   *GEODESICS, *LUNAR PROBES, *MOON, ALTIMETERS, EXTRATERRESTRIAL TOPOGRAPHY, HEIGHT FINDING, HORIZONTAL INDICATORS, OPTICAL INSTRUMENTS, SPACE NAVIGATION

Distribution Statement : APPROVED FOR PUBLIC RELEASE