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Image Orthicon (Day/Night) Camera

NSSDCA ID: 1968-068A-03

Mission Name: ATS 4
Principal Investigator:Mr. John C. Moody


The ATS 4 image orthicon (day/night) camera was designed to determine the feasibility of simultaneous day/night imaging of cloudcover patterns from an earth-synchronous spacecraft. The camera, whose optical axis was oriented perpendicular to the spacecraft's spin axis, viewed the earth through a special aperture in the spacecraft's side. Camera optics consisted of a two-axis steerable primary mirror, an objective lens, a beam splitter, a photomultiplier tube (pmt), a mechanical sun shade, two variable density filter wheels, and a 5.08-cm-diameter orthicon tube. The two density filters operated in conjunction with the pmt to automatically regulate the amount of light striking the highly light-sensitive orthicon tube. The sun shade was also controlled by the pmt and protected the image orthicon camera from accidentally pointing the optics toward the sun. The optics were steerable by ground command. Steps of 0.1 deg through an angle of plus or minus 11.2 deg in both pitch and roll were possible. Thus the camera could track areas of meteorological interest, knowing the spacecraft altitude and location of the desired viewing area. The camera had a 3-deg field-of-view, which corresponded to an earth coverage of approximately 1700 sq km, with a horizontal resolution of better than 4 km at nadir. Full earth coverage could be achieved by taking a series of overlapping pictures. The data were to be transmitted (60 kHz) in near real time. ATS 4 failed to achieve its planned geosynchronous orbit. The booster rocket remained attached to the spacecraft and hindered attitude control. Due to the spacecraft's anomalistic attitude, no pictures were obtained although telemetry did indicate that the system was working.

Alternate Names

  • ATS4/ImageOrthicon_Day/Night_Camera

Funding Agency

  • Unknown (United States)


    Additional Information

    Questions and comments about this experiment can be directed to: Coordinated Request and User Support Office



    NameRoleOriginal AffiliationE-mail
    Mr. John C. MoodyPrincipal InvestigatorNASA Goddard Space Flight Center
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