A RADAR INTERFEROMETER STUDY OF VENUS AT 3.8 CM
Abstract
The 120-foot antenna of the Haystack Microwave Facility and the 60- foot antenna of the Westford Communications Terminal, both operated by M.I.T. Lincoln Laboratory, were coupled to form a planetary radar interferometer operating at X-band and were used to observe Venus at a wavelength of 3.8 cm during the 1967 inferior conjunction. The antennas are separated by approximately 4000 feet along a line 22 degrees east of north. At maximum projection in the direction of the planet, this baseline gives a fringe spacing of 5 seconds of arc, or a maximum of about 10 fringes across the planetary disk at inferior conjunction. By transmitting a CW signal from the 120-foot antenna and frequency analyzing the received echo, it was possible to resolve the planetary surface scattering into strips parallel to the apparent axis of rotation. Crosscorrelation of the complex frequency components obtained at the two sites yielded corresponding spatial Fourier components which resolved the scattering along the strips. With 1-Hz frequency resolution and a maximum of 10 fringes along the rotation axis, the planetary hemisphere visible to the radar during inferior conjunction was mapped with approximately 100 resolution intervals along a direction perpendicular to the apparent rotation axis, with 10 resolution intervals in the orthogonal direction. For a limited region on the planet, surrounding the center of the visible disk, higher resolution was obtained by transmitting pulses of 500-microsec effective length. Maps obtained from the observations show Venus to be smoother on the average than the moon at 3.8 cm, although some regions of the planet exhibit strong local radar- scattering enhancement.
Document Details
- Document Type
- Technical Report
- Publication Date
- Feb 14, 1968
- Accession Number
- AD0670167
Entities
People
- Alan E. E. Rogers
- F. S. Weinstein
- G. H. Pettengill
- James I. Levine
- Richard A. Brockelman
- Richard P. Ingalls
- Tor Hagfors
Organizations
- Massachusetts Institute of Technology