(U) The Midcourse Space Experiment (MSX) observatory is a Ballistic Missile Defense Organization (BMDO) project, which offers major benefits for both the defense and civilian sectors. MSX will aid future spacecraft design by monitoring on-orbit contamination of optical instruments. In addition, its investigation of the composition and dynamics of Earth's atmosphere promises increased understanding of the environment.
(U) MSX will track along the orbits of three known resident space objects (RSO) that have fragmented: Cosmos 2227 in LEO, a Titan transtage rocket booster in GEO, and Cosmos 278 in a geotransfer (highly eccentric) orbit. A search around these known objects while
tracking at the rate of the parent RSO should permit identification of debris pieces generated by the fragmentation. Multi-spectral data from the SBV, SPIRIT III, and UVISI instruments can be combined to yield information about the albedo (percent reflectivity) and size of the object. These results will address the existence of radar-transparent debris and provide data to update existing models at these altitudes.
(U) When the fragmentation of an object occurs, the SBV and UVISI instruments will track the dispersing pieces during the days-to-months after the fragmentation. The dynamics of the fragmentation can then be studied, yielding information about the cause of the event.
(U) Limited measurements of the on-orbit flux of debris onto a given space platform have been made. The SBV can search in preferential locations from which the current model predicts most of the orbital debris will come. Objects seen in specific directions over a given time
period will be counted. The data will contribute to the design of specific strategies for early warning of debris collision.
(U) The MSX represents the first system demonstration of technology in space to identify and track ballistic missiles during their midcourse flight phase. MSX is to be launched aboard a Delta II booster from Vandenberg Air Force Base in California. Insertion altitude is approximately 900 km, in a high-inclination, circular, near-sun synchronous orbit. Mission design lifetime is 4 years, with the SPIRIT III infrared telescope limited by coolant supply to 18-20 months of operation. Approximately 50% of MSX's weight and power is allocated to instrument use. During its primary mission, or "cryogen" phase, MSX is designed to gather data on backgrounds and to detect and track test-ICBMs launched from the Western Test Range (WTR) and targeted at the Kwajalein Missile Range in the Pacific. Other targets include ICBMs launched from Barking Sands in Hawaii, satellites, and objects deployed from MSX itself. The "post-cryogen" phase will focus on celestial and terrestrial backgrounds, surveillance demonstrations, and contamination and environmental research.
(U) MSX will provide unique opportunities to observe man-made debris in Low Earth Orbit (LEO) and Geosynchronous Orbit (GEO) by searching known debris streams for unknown objects, observing the dispersal of fragments after the catastrophic destruction of a resident
space object, and detecting objects that may be on or close to collision orbits with MSX. Above an altitude of 500 km, knowledge of man-made orbital debris is incomplete for debris 10 to 30 cm in diameter and largely unknown at less than 10 cm diameter. MSX will orbit at 900 km, where current models predict the greatest amount of man-made debris in LEO. The figure shows the distribution of the objects 210 cm in diameter currently tracked by the U.S. Space Command. The existing model assumes that the distribution of smaller objects throughout LEO is proportional to the larger ones.
(U) Spacecraft Design
(U) The 2,700-kg, 510-cm-long MSX spacecraft includes three major sections, each with 150-cm by 150-cm cross section:
- (U) 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 reaction wheel-driven attitude control system achieves real-time pointing accuracy of better than 0.1? and postprocessing knowledge of 9 microrads. Line-of-sight jitter is held to ?9 microrads over instrument integration durations of approximately 1 second. MSX will operate in the background data-gathering mode an average of 20 minutes per orbit, with tracking test lasting 35 minutes. The system provides "parked" safe mode for thermal recovery, cryogen conservation, and battery recharge between test cycles.
- (U) The mid-section graphite epoxy truss supports the large cryogenic dewar, which contains frozen hydrogen at approximately 8.5 K. The thermal design of the mid-section maintains the outer shell of the dewar at approximately 200 K. The 200-cm-long truss thermally isolates the heat-sensitive instrument section from the much warmer spacecraft bus.
- (U) The instrument section houses 11 optical sensors, which are precisely aligned so target activity can be viewed simultaneously by multiple sensors. MSX is capable of observations at a wide range of infrared, visible and ultraviolet wavelengths from 110 nm to 28 ³m.
- (U) SPIRIT III (Space Infrared Imaging Telescope) - The cryogenically cooled long-wave infrared sensor (LWIR) in SPIRIT III is the most advanced infrared instrument yet launched into space. Developed by the Space Dynamics Laboratory of Utah State University, SPIRIT III includes a five-color, high-spatial-resolution scanning radiometer and a six-channel, high-spectral-resolution, Fourier-transform spectrometer.
- (U) UVISI (Ultraviolet and Visible Imagers and Spectrographic Imagers) - A JHU/APL-built instrument with five spectrographic imagers and four UV and visible imagers, UVISI affords complete spectral and imaging capabilities from the far ultraviolet through visible wavelengths.
- (U) SBV (Space-Based Visible) Instrument - The SBV, equipped with a charge-coupled device, is a visible band telescope with a 6-inch aperture and image processing electronics. Built by the MIT/Lincoln Laboratory, SBV will demonstrate an above-the-horizon surveillance capability in visible wavelengths from a space platform.
- (U) OSDP (On-board Signal and Data Processor)- Built by Hughes Aircraft Company, the OSDP uses data from SPIRIT III in real-time signal processing for target detection and tracking. It also will provide information about radiation effects on state-of-the-art semiconductor devices.
(U) REFERENCE OBJECTS - These small (2.0 cm) reference spheres, provided by the MIT/Lincoln Laboratory, will be deployed from MSX for instrument calibration.
(U) To be supplied.
|Delta II||Delta II|
|SBIRS-Low||Space-Based Infrared System - Low Earth Orbit (SBIRS-Low)|
|Western Range||Western Range|
|Space-Based Warning||Space-Based Warning Systems|
|SURVEILLANCE AND WARNING||SPACE FORCE ENHANCEMENT: SURVEILLANCE AND WARNING|
(U) National Security Space Road Map Team, NSSA, Open Phone: (703) 808-6040, DSN 898-6040.
(U) 21 November 1997
(U) Road Map Production Date: 23 June 2001