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Ranger 8 Vidicon Television Cameras

NSSDCA ID: 1965-010A-01

Mission Name: Ranger 8
Principal Investigator:Dr. Gerard P. Kuiper

Description

The television system consisted of six slow scan vidicon TV cameras capable of transmitting high-resolution closeup television pictures of the lunar surface during the final minutes of flight, before the spacecraft impacted the lunar surface. These photographs provided large-scale topographic information needed for the Surveyor and Apollo projects. Vidicons 2.54 cm in diameter with an antimony-sulfide oxy-sulfide (ASOS) photoconductor target were used for image sensing in all six cameras. There were two camera channels which had independent power distribution networks so that the greatest reliability and probability of obtaining highest quality video pictures would be afforded. The first channel had two full-scan cameras, one wide angle (25 degree field of view and 25-mm focal length) designated the A-camera and one narrow angle (8.4 degree field of view and 76-mm focal length) B-camera. These cameras utilized an active image area of 11 sq mm that contained 1150 lines and was scanned in 2.5 sec. Scan and erase cycles were designed to act alternately, resulting in intervals of 5 sec between consecutive pictures on a particular camera. The other channel had four partial-scan (p) cameras, two narrow angle and two wide angle. The image a area of these four cameras was 2.8 sq mm, contained 300 lines, and was scanned in 0.2 sec. The TV system allowed for camera fields of view, which ranged from 25 deg to 2.1 deg, to overlap and produce a 'nesting' sequence of pictures.

Electromagnetically driven slit-type shutters exposed the vidicons. Images were focused on the vidicon target, which was made up of a layer of photoconductive material initially charged by scanning with an electron beam. An electron beam then scanned the surface and recharged the photoconductor. The video signal was amplified several thousand times, sent to the transmitter where amplitude variations were converted to frquency variations, and were then transmitted directly to Earth. At the end of the active scan, the camera entered an erase cycle to prepare it for the next exposure. Twelve P-channel pictures were exposed between each F-channel picture.

The video transmissions were sent to a television receiver and recorded on both kinescope film recorders and magnetic tape recorders. A cathode-ray tube reconstructed the original image, which was then photographed on 35-mm film. Both full-scan and partial-scan camera systems operated during the final 23 min of flight, 0934 UT to 0957 UT, on February 20, 1965. Resolution was achieved to 1.5 m. The experiment returned 6597 partial-scan and 540 full-scan pictures giving the desired broad coverage of the lunar surface.

Alternate Names

  • Ranger 8 Impact Television Imaging
  • Ranger8/Ranger8VidiconTelevisionCameras

Facts in Brief

Mass: 173 kg

Discipline

  • Planetary Science: Geology and Geophysics

Additional Information

Questions and comments about this experiment can be directed to: Dr. David R. Williams

 

Personnel

NameRoleOriginal AffiliationE-mail
Dr. Robert J. NaumannOther InvestigatorNASA Marshall Space Flight Centerrobert.j.naumann@email.uah.edu
Dr. Eugene M. ShoemakerOther InvestigatorCalifornia Institute of Technology
Dr. Ewen A. WhitakerOther InvestigatorUniversity of Arizona
Dr. Harold C. UreyOther InvestigatorUniversity of California, San Diego
Mr. Raymond L. HeacockOther InvestigatorNASA Jet Propulsion Laboratory
Dr. Gerard P. KuiperPrincipal InvestigatorUniversity of Arizona

Selected References

  • Ranger 7,8, and 9 TV cameras, NASA-GSFC, NSSDC 68-06, Greenbelt, MD, May 1968.
  • Ranger 8 observes the Sea of Tranquillity, Spaceflight, 7, 83-84, May 1965.
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