The Scout family of rockets were launch vehicles designed to place small satellites into orbit around the Earth. The Scout multistage rocket was the first (and for a long time, the only) orbital launch vehicle to be entirely composed of solid fuel stages.
The original Scout (an acronym for Solid Controlled Orbital Utility Test system) was designed in 1957 at the NACA Langley center. Scouts were used from 1961 until 1994. To enhance reliability the development team opted to use "off the shelf" hardware, originally produced for military programs. According to the NASA fact sheet:
... the first stage motor was a combination of the Jupiter Senior and the Navy Polaris; the second stage came from the Army MGM-29 Sergeant; and the third and fourth stage motors were designed by Langley engineers who adapted a version of the Navy Vanguard.[1]
The first successful orbital launch of a Scout, on February 16, 1961, delivered Explorer 9, a 7-kg satellite used for atmospheric density studies, into orbit.[2] The final launch of a Scout, using a Scout G-1, was on May 9, 1994. The payload was the Miniature Sensor Technology Integration 2 (MSTI-2) military spacecraft with a mass of 163 kg, which remained in orbit until 1998.[3]
The standard Scout launch vehicle was a solid propellant, four-stage booster system, approximately 75 feet (23 m) in length with a launch weight of 47,398 pounds (21,500 kilograms.)[4]
Contents |
Stage 1: Algol
Stage 2: Castor
Stage 3: Antares
Stage 4: Altair
In the late 1950s, NASA established the Scout program to develop a multistage solid-propellant space booster and research rocket. The U.S. Air Force also participated in the program, but different requirements led to some divergence in the development of NASA and USAF Scouts.
The basic NASA Scout configuration, from which all variants were derived, was known as Scout-X1. It was a four-stage rocket, which used the following motors:
Scout's first-stage motor was based on an earlier version of the Navy's Polaris missile motor; the second-stage motor was developed from the Army's Sergeant surface-to-surface missile; and the third- and fourth-stage motors were adapted by NASA's Langley Research Center; Hampton, VA, from the Navy's Vanguard missile.[4]
The Scout-X1 first flew successfully on 1960-10-10, after an earlier failure in July 1960. The rocket's first stage had four stabilizing fins, and the vehicle incorporated a gyro-based guidance system for attitude stabilization to keep the rocket on course.
Some other Scout designations were:
The USAF Scout program was known as HETS (Hyper Environmental Test System) or System 609A, and the rockets were generally referred to as Blue Scout. The prime contractor for the NASA Scout was LTV, but the Blue Scout prime contractor was Ford Aeronutronics.
By using different combinations of rocket stages, the USAF created several different Blue Scout configurations. One of these was the XRM-89 Blue Scout I, which was a three-stage vehicle, using Castor 2 and an Antares 1A stages, but omitting the basic Scout's Altair 4th stage. The first launch of an XRM-89 occurred on 1961-01-07, and was mostly successful. On that flight, the XRM-89 carried a variety of experiments to measure rocket performance and high-altitude fields and particle radiation. The payload was located in a recoverable reentry capsule, but the capsule sank before it could be recovered from the water. The only other XRM-89 launches (in May 1961 and April 1962) were unsuccessful, and the Blue Scout I program was terminated in 1962.
The XRM-90 Blue Scout II was a rocket of the U.S. Air Force's System 609A Blue Scout family. The XRM-90 was a four-stage rocket, which used the same stages as the basic NASA Scout. It was nevertheless not identical to the latter, because the 4th stage was hidden in a payload fairing with the same diameter as the 3rd stage, and the first stage nozzle used a flared tail skirt between the fins. Externally, the XRM-90 was indistinguishable from the XRM-89 Blue Scout I.
The first XRM-90 launch occurred on 1961-03-03, followed by a second one on 1961-04-12. Both sub-orbital flights were successful, and measured radiation levels in the Van Allen belts. The second Blue Scout II also carried a micrometeorite sampling experiment, but the recovery of the reentry capsule failed. The third XRM-90 was used by NASA in November 1961 for Mercury-Scout 1. This was an attempt to orbit a communications payload for Project Mercury, but the rocket failed after 28 seconds of flight. The USAF subsequently abandoned the XRM-89 Blue Scout I and XRM-90 Blue Scout II vehicles, and shifted to the RM-91/SLV-1B Blue Scout Junior instead.
The XRM-91 Blue Scout Junior (sometimes called Journeyman B) was a rocket of the U.S. Air Force's System 609A Blue Scout family.[11] Although the Blue Scout Junior had sufficient impulse to have put a small satellite in low-earth orbit, it was not used as an orbital launch vehicle. The XRM-91 did not resemble the other Scout variants externally, because the usual first Scout stage (an Aerojet General Algol) was not used. Instead, the four-stage Blue Scout Junior used Scout's 2nd and 3rd stages (Castor and Antares) as the first two stages, and added an Aerojet General Alcor and a spherical NOTS Cetus in a common nose fairing. The XRM-91 also lacked the gyro-stabilization and guidance system of the RM-89 Blue Scout I and RM-90 Blue Scout II, making it a completely unguided rocket. It relied on second-stage fins and two spin motors to achieve a stable flight trajectory.
The first launch of an XRM-91 occurred on September 21, 1960, making it actually the first Blue Scout configuration to fly. The flight was planned to make radiation and magnetic field measurements at distances of up to 26 700 km (16 600 miles) from earth, and while the rocket did indeed achieve this altitude, the telemetry system failed so that no data was received. The second launch in November ended with a failure during second stage burn. The third flight was to measure particle densities in the Van Allen belts and reached a distance of 225 000 km (140 000 miles), but again a telemetry failure prevented the reception of scientific data. The fourth and final XRM-91 mission in December 1961 also carried particle detectors, and was the only completely successful flight of the initial Blue Scout Junior program.
The Blue Scout Junior was regarded by the USAF as the most useful of the various Blue Scout configurations. It was used (in slightly modified form) between 1962 and 1965 by the Air Force as the SLV-1B/C launch vehicle for suborbital scientific payloads. The SLV-1C was also chosen as the rocket for the MER-6A interim ERCS (Emergency Rocket Communications System) vehicle. NASA used a three-stage Blue Scout Junior configuration (omitting the Cetus 4th stage) as the RAM B.
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