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- ATS 4 was launched in August 1968 and was a gravity-gradient-stabilized spacecraft designed to (1) test new concepts in spacecraft design, propulsion, and stabilization, (2) take high-quality cloud cover pictures, (3) provide in situ measurements of the aerospace environment, and (4) test improved communication systems while in earth-synchronous orbit. The cylindrically-shaped spacecraft measured 142 cm in diameter and 183 cm in length. The primary structural members were 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 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. This satellite featured an image orthicon (day/night) camera for the purpose of determining the feasibility of simultaneous day/night imaging of cloud cover patterns from an earth-synchronous spacecraft. The second stage of the launch vehicle failed to 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 the anomalistic attitude, some of the experiments did perform successfully before the satellite and its attached rocket 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. Group: Platform_Details Entry_ID: ATS-4 Group: Platform_Identification Platform_Category: Earth Observation Satellites Platform_Series_or_Entity: ATS (Advanced Technology Satellite) Short_Name: ATS-4 Long_Name: Advanced Technology Satellite-4 End_Group Creation_Date: 2007-08-29 Online_Resource: http://www.astronautix.com/craft/ats4.htm Group: Platform_Logistics Launch_Date: 1968-08-10 Primary_Sponsor: NASA End_Group End_Group
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