INFRARED BALLOON ASTRONOMY.
Abstract
The report describes instrumentation used in a balloon gondola to make infrared astronomical studies of Venus with a telescope of 16 inches aperture at 16 miles' altitude. With it, water vapor was discovered above the clouds in the Cytherean atmosphere; and ice was identified as the composition of the clouds themselves. Solutions to optical and spectroscopic problems, in connection with these scientific missions, are described. For the water vapor determination, a photomultiplier with S-1 photocathode, cooled by a dry ice refrigerator, was used behind the multiple exit slits (21) of a modified Ebert spectrometer. For the cloud determination, multiple indium arsenide detectors (3), similarly cooled, were focused on the exit focal plane of the spectrometer. Gratings served to disperse the spectrum. An aspheric mirror corrected aberration of the spherical primary mirror. An off-axis lens corrected residual aberrations in the spectrometer. The automatic acquisition and tracking, at altitude, using variable off-set angles, from the sun as the fiducial point, is considered both instrumentally, and as a navigation problem. Laboratory measures of the reflectivity of various candidate cloud materials are presented, with a description of equipment used. The scientific results are described in detail and some interpretations are given. (Author)
Document Details
- Document Type
- Technical Report
- Publication Date
- Jul 01, 1966
- Accession Number
- AD0643567
Entities
People
- John Strong
Organizations
- Johns Hopkins University