The Scout family of rockets were launch vehicles designed to place small satellites into orbit around the Earth. 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 from 1961 until 1994. Unlike other satellite launchers, all Scout stages were solid fueled. 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 a MSTI military spacecraft with a mass of 163 kg, which remained in orbit until 1998.^[3]

Technical data

Scout A overview

• Thrust at liftoff: 513.40 kN (52,352 kgf)
• Mass at launch: 17,850 kg
• Diameter: 1.01 m
• Length: 25.00 m

Scout A stages

Stage 1:

• Algol
• Gross Mass: 11,600 kg
• Empty Mass: 1,650 kg
• Vacuum thrust: 564.25 kN (57,537 kgf)
• Burn time: 47 s
• Diameter: 1.01 m
• Span: 1.01 m
• Length: 9.09 m

Stage 2:

• Castor
• Derived from Sergeant missile
• Gross Mass: 4,424 kg
• Empty Mass: 695 kg
• Vacuum thrust: 258.92 kN (26,402 kgf)
• Burn time: 37 s
• Diameter: 0.79 m
• Span: 0.79 m
• Length: 6.04 m

Stage 3:

• Gross Mass: 1,400 kg
• Empty Mass: 300 kg
• Vacuum thrust: 93.09 kN (9,493 kgf)
• Burn time: 36 s
• Diameter: 0.78 m
• Span: 0.78 m
• Length: 2.90 m

Stage 4:

• Gross Mass: 275 kg
• Empty Mass: 37 kg
• Vacuum thrust: 22.24 kN (2,268 kgf)
• Burn time: 28 s
• Diameter: 0.64 m
• Span: 0.64 m
• Length: 2.53 m

NASA use

In the late 1950s, the 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:

• 1st stage: Aerojet General Algol
• 2nd stage: Thiokol XM33 Castor
• 3rd stage: Allegany Ballistics Lab X-254 Antares
• 4th stage: Allegany Ballistics Lab X-248 Altair

Satellites that were put into orbit:

• AEREOS and AEROS B atmospheric research^[4]

The Scout-X1 first flew successfully on 10 October 1960, 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 Scout X-2 which in 1962 introduced the Antares-2 stage upgrade.
• The Scout X-3 which in 1963 introduced the Algol-2 upgrade.
• The Scout A-1 and B-1 which in 1965 introduced the Castor-2 and Altair-3 upgrades, respectively.
• The Scout D-1 which in 1972 introduced the Algol-3 upgrade.

Military use--Blue Scout I

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 7 January 1961, 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 sunk in the water before it could be recovered. The only other XRM-89 launches (in May 1961 and April 1962) were unsuccessful, and the Blue Scout I program was terminated in 1962.

Blue Scout II

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 3 March 1961, followed by a second one on 12 April 1961. 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 in an attempt to launch a communications payload for Project Mercury into orbit, but this rocket failed. 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.

Blue Scout Junior

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. 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 21 September 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 26700 km (16600 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 225000 km (140000 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 would have been easily powerful enough to put a small satellite in low-earth orbit but was never used to do so.

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.

References

External links

• Profile of the Blue Scout Junior
• Specifications and chronology of the Scout A

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