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The IUS is 17 ft. long, 9 ft. in diameter and weighs more than 32,000 lb., including 27,000 lb. of solid fuel propellant. The IUS consists of an aft skirt; an aft stage containing 21,000 lb. of solid propellant fuel, generating 45,000 lb. of thrust; an interstage; a forward stage containing 6,000 lb. of propellant, generating 18,500 lb. of thrust; and an equipment support section. The equipment support section contains the avionics which provide guidance, navigation, telemetry, command and data management, reaction control and electrical power.

Solid propellant rocket motors were selected in the  design of the IUS because of their compactness, simplicity, inherent safety, reliability and lower cost.

The IUS is built by Boeing Aerospace Corp., Seattle, under contract to the U.S. Air Force Systems Command.  Marshall Space Flight Center, Huntsville, Ala., is NASA's lead center for IUS development and program management of NASA-configured IUSs procured from the Air Force.


For the Spartan-Halley mission, NASA's Goddard Space Flight Center and the University of Colorado's Laboratory for Atmospheric and Space Physics (LASP) have recycled several instruments and designs to produce a low-cost, high-yield spacecraft to watch Halley's Comet when it is too close to the sun for other observatories to do so.

It will record ultraviolet light emitted by the comet's chemistry when it is closest to the sun and most active so that scientists may determine how fast water is broken down by sunlight, search for carbon and sulfur atoms and related compounds, and understand how the tail evolves.

Principal investigator is Dr. Charles Barth of the University of Colorado LASP. Mission manager is Morgan Windsor of Goddard Space Flight Center.

The Instruments

Two spectrometers, derived from backups for a Mariner 9 instrument which studied the Martian atmosphere in 1971, have been rebuilt to survey Halley's Comet in ultraviolet light from 128 to 340 nanometers (nm) wavelength, stopping just above the human eye's limit of about 400 nm.

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