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ATS 4 (Applications Technology Satellite) was a gravity-gradient-stabilized spacecraft designed to (1) test new concepts in spacecraft design, propulsion, and stabilization, (2) take high-quality cloudcover pictures, (3) provide in situ measurements of the aerospace environment, and (4) test improved communication systems while in an earth-synchronous orbit. The cylindrically-shaped spacecraft measured 142 cm in diameter and 183 cm in length. The spacecraft structure consisted primarily of a corrugated thrust tube with honeycombed bulkheads secured to each end. Equipment components and payload were externally mounted on the outer surface of the thrust tube as well as on a structure that slid into the interior of the thrust tube. Electric power was provided by two solar arrays mounted on either end of the spacecraft's outer shell and by two rechargeable nickel-cadmium batteries. Extending radially outward from the side of the spacecraft were four 28.2-m-long adjustable gravity-gradient booms. The spacecraft telemetry system consisted of four 2.1-W transmitters, (two at 136.47 MHz and two at 137.35 MHz), in addition to a microwave communications experiment. The second stage of the launch vehicle failed to ignite, and the planned synchronous orbit was not achieved. The spacecraft and its Centaur booster rocket were left attached together in a parking orbit. In spite of an anomalistic attitude, some of the experiments did perform successfully before the satellite and its attached booster reentered the earth's atmosphere on October 17, 1968. The primary objective of inserting a gravity-gradient-stabilized spacecraft into a geosynchronous orbit was not accomplished.

Alternate Names

  • 03344
  • ATS-D
  • ATS4
  • Advanced Tech. Sat. 4
  • PL-683A

Facts in Brief

Launch Date: 1968-08-10
Launch Vehicle: Atlas-Centaur
Launch Site: Cape Canaveral, United States
Mass: 305 kg

Funding Agency

  • NASA-Office of Space Science Applications (United States)


  • Communications
  • Engineering
  • Earth Science

Additional Information

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



NameRoleOriginal AffiliationE-mail
Mr. John M. TholeProject ManagerNASA Goddard Space Flight Center
Dr. Thomas L. AggsonProject ScientistNASA Goddard Space Flight Center
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