The MSX Midcourse Space eXperiment observatory was a BMDO sponsored mission designed to demonstrate a variety of multispectral imaging technologies to identify and track ballistic missiles during flight. In addition, it performed scientific investigations of the composition and dynamics of the Earth's atmosphere by observing ozone, chlorofluorocarbons, carbon dioxide and methane.

The spacecraft was 3-axis stabilized to 0.01 deg using reaction wheels with knowledge to 9 µ rad (post-processed). 108 Gbits data storage were available. Communiations were via steerable X-band antennas with 2 kbps uplink and downlink up to 25 Mbps. Dual solar arrays (single-axis articulation) provided 1200 W BOL and recharged NiH2 batteries. The instruments consisted of 11 optical sensors making observations at a wide range of infrared, visible and ultraviolet wavelengths from 110 nm to 28 µ m. Primary instruments were the SPIRIT III (Space Infrared Imaging Telescope), UVISI (Ultraviolet and Visible Imagers and Spectrographic Imagers), SBV (Space-Based Visible instrument), and OSDP (On-board Signal and Data Processor). Reference objects (2 cm spheres) were to be deployed from MSX for observation by the sensors.

The initial project started 1988 with an estimated cost of $ 800 million. This was reduced to $ 350 million. Spacecraft cost was estimated at $325M. Utah State University built SPIRIT III, Hughes the OSDP.

Design Life: 4 years (with 18-20 months of coolant for IR senso. Typical orbit: 900 km, high inclination, circular, near-sun-synch. Length: 5.10 m (16.70 ft). Maximum Diameter: 1.50 m (4.90 ft). Mass: 2,700 kg (5,900 lb). Associated Launch Vehicle: Delta 7000.

• 1996 April 24 - MSX - Launch Site: Vandenberg. Launch Vehicle: Delta. Mass: 2,700 kg (5,900 lb). Perigee: 897 km (557 mi). Apogee: 907 km (563 mi). Inclination: 99.40 deg. Period: 103.10 min.

  LEO. Midcourse Space eXperiment; missile detection technology tests; also used for auroral and atmospheric studies