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| | Spaceflight Now | Proton Launch Report | The Proton rocket |
 | | Proton's three-stage configuration is used primarily to launch large payloads into low earth orbit, while the four-stage configuration is used to launch spacecraft into high-energy trajectories (geo-transfer, geosynchronous, geostationary, and interplanetary). |
 | | Proton's fourth stage possesses a multiple restart capability that allows it to perform all orbit change maneuvers necessary to place a spacecraft into its final orbit, without requiring use of the spacecraft's on-board propellant supply. |
 | | The Proton model numbers D, D-1, D-1-e, SL-13, and SL-12 are the designations currently in common use in the United States, with the D numbers having been applied by the Library of Congress and the SL numbers originating with the U.S. Department of Defense. |
| www.spaceflightnow.com /proton/astra1k/proton.html (1255 words) |
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