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| Midcourse Space Experiment |
| Prime: Jeffrey Ashby |
| Backup: Eileen Collins |
| Overview |
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The objective of the Midcourse Space Experiment (MSX) is to fire the orbiter thrusters (orbital maneuvering and primary reaction control systems) in space and use the sophisticated sensors of the orbiting MSX satellite to collect ultraviolet, infrared, and visible light data of the event. The MSX spacecraft features an advanced multispectral imaging capability that is used to gather data on test targets and space background phenomena. This information will aid designers of future space- and ground-based surveillance and tracking systems that require simultaneous wideband optical data on midcourse missile flight, the trajectory phase between burnout and reentry. For the first time, researchers can observe missile target signatures against Earth limb, auroral, and celestial cluttered backgrounds. In addition, MSX will investigate the composition and dynamics of Earth's atmosphere to increase our understanding of the environment. MSX can be pointed so that all its instruments simultaneously view the Earth's atmosphere in any allowed direction. This represents an unparalleled scientific opportunity to study the composition, dynamics, and energetics of the atmosphere, including small annual changes in such chemicals as ozone, carbon dioxide, and chlorofluorocarbons. Global atmospheric changes following major solar disturbances and environmental events like volcanic eruptions, forest fires, and agricultural burnoffs also can be monitored. The MSX spacecraft includes three major sections. The versatile electronics section features state-of-the-art attitude control, power, and command and telemetry systems, including rotatable solar arrays, nickel-hydrogen battery power, steerable X-band antennas, and 108-Gbit data storage. The midsection graphite-epoxy truss supports a large cryogenic Dewar, which contains frozen hydrogen at approximately 8.5 kelvins (1 kelvin equals -273 degrees Celsius, the temperature at which water freezes). The truss thermally isolates the heat-sensitive instrument section from the much warmer spacecraft bus. The instrument section houses 11 optical sensors, which are precisely aligned so that target activity can be viewed simultaneously by multiple sensors. The primary instruments are a space infrared imaging telescope, ultraviolet and visible imagers and spectrographic imagers, a space-based visible instrument, an on-board signal and 86 data processor, and reference objects deployed from MSX for calibrating its instruments. There are three major categories of MSX tests: plume observations, resident space object (RSO) observations, and acquisition and tracking tests. Plume observations require the firing of either an orbital maneuvering system engine or a minimum of two primary reaction control system engines. The engines fire into the ram, into the wake, or at an angle to the orbiter's velocity vector. RSO tests require the orbiter to maneuver to a specified attitude and remain there throughout the test. During the mission, MSX sensors will obtain ultraviolet, infrared, and visible light data of orbiter thruster firings under controlled conditions. Data collection will be scheduled during any encounter opportunity when orbiter and crew support activities can be planned within primary payload or mission objectives. There are no unique altitude or inclination requirements, and no on-board flight hardware is involved. The Sensor Technology Directorate of the BMDO has overall responsibility for MSX. Johns Hopkins University Applied Physics Laboratory serves as systems engineer and technical adviser. |
| History/Background |
| The MSX satellite was launched from Vandenberg Air Force Base in California on April 24, 1996, into a 99-degree-inclination, 485-nautical-mile orbit. Its design lifetime is four years, but its infrared telescope is limited by its coolant supply to 18 to 20 months of operation. Approximately 50 percent of MSX's weight and power is allocated to instrument use. |
| Benefits |
| The MSX observatory, a Ballistic Missile Defense Organization (BMDO) project, offers major benefits for both the defense and civilian sectors. MSX will observe firings of the orbiter maneuvering thrusters and the orbiter itself. With a solid heritage in the successful Delta series, MSX represents the first system demonstration of technology in space to identify and track ballistic missiles during their midcourse flight phase. The satellite will also collect valuable data about changes in the Earth's atmosphere. |
Editorial/Technical Comments: ShuttlePresskit
