The first launch of Scout B, in 1965.
FunctionOrbital launch vehicle
ManufacturerLTV Aerospace Corporation[1]
Country of originUnited States
Launch history

The Scout family of rockets were American launch vehicles designed to place small satellites into orbit around the Earth. The Scout multistage rocket was the first orbital launch vehicle to be entirely composed of solid fuel stages. It was also the only vehicle of that type until the successful launch of the Japanese Lambda 4S in 1970.

The original Scout (a backronym for Solid Controlled Orbital Utility Test system) was designed in 1957 at the NACA, at Langley center. Scout launch vehicles 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."[2]

The first successful orbital launch of a Scout, on February 16, 1961, delivered Explorer 9, a 7 kilograms (15 lb) satellite used for atmospheric density studies, into orbit.[3] The final launch of a Scout, using a Scout G-1, was on May 8, 1994, from Vandenberg Air Force Base. The payload was the Miniature Sensor Technology Integration Series 2 (MSTI-2) military spacecraft with a mass of 163 kilograms (359 lb). MSTI-2 successfully acquired and tracked a LGM-30 Minuteman missile.[4][5][6]

The standard Scout launch vehicle was a solid propellant, four-stage booster system, approximately 23 meters (75 ft) in length with a launch weight of 21,499 kilograms (47,397 lb).[7]

Scout A

The Scout A was used for launches of the Transit NNSS series, placing two satellites in orbit at the same time. Twelve flights were conducted between 21 December 1965 and 27 August 1970. It was also used to launch a British scientific satellite. Standard payload capability was 122 kg into a low-Earth orbit.[8]


Scout vehicle general arrangement

Stage 1: Algol

Stage 2: Castor

Stage 3: Antares

Stage 4: Altair

Scout-X1 (NASA)

Main article: Scout X-1

First launch of satellite on Scout X-1 - Explorer 9, Wallops, 16 Feb 1961

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.[7] Unlike the Thor or Atlas-Agena the Scout was non-military and could be sold to foreign customers.[9]

The Scout X-1 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.

Satellites orbited

This list is incomplete; you can help by adding missing items. (August 2008)

Scout X-1A

Main article: Scout X-1A

Scout X-1A was an American sounding rocket which was flown in 1962.[16] It was a five-stage derivative of the earlier Scout X-1, with an uprated first stage, and a NOTS-17 upper stage.

Scout X-2

Main article: Scout X-2

Scout X-2 was an American expendable launch system and sounding rocket which was flown twice in 1962. It was a four-stage rocket, based on the earlier Scout X-1, introducing the Algol 1D[17] and Antares IIB stage upgrades. On 1962-08-23 a Scout X-2 was used for the first successful launch of a DMSP satellite, lifting off from Point Arguello near Vandenberg Air Force Base.[18][19]

Scout X-3

Scout X-3 with first British built satellite Ariel 2, 1964

The Scout X-3 flew after 1962 and introduced the Algol IIA upgrade.[20]

Scout X-4

Scout X-4 with first Italian satellite San Marco 1, 1964

The Scout X-4 flew after 1963 and introduced Altair 2 upgrade.[21]

Scout A-1

Main article: Scout A-1

The Scout A-1 flew in 1973 and introduced the Castor IIA upgrades.[22]

Scout B-1

The Scout B-1 flew after 1971 and introduced the Altair III upgrades.[23]

Scout D-1

Main article: Scout D-1

The Scout D-1 flew in 1972 and introduced the Algol III upgrade.[24]

Scout F-1

The Scout F-1 flew twice in 1975.[25]

Scout G-1

The Scout G-1 flew from 1974 until the Scout's retirement in 1994.[26] It was rated to orbit a 210 kg payload.

XRM-89 Blue Scout I (USAF)

Main article: RM-89 Blue Scout I

Blue Scout I on LC-18 in 1961

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.

XRM-90 Blue Scout II (USAF)

Main article: RM-90 Blue Scout II

Mercury-Scout 1, an Air Force Blue Scout II launched for NASA

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.

Blue Scout II parameters

Parameter 1st Stage 2nd Stage 3rd Stage 4th Stage
Gross Mass 10,705 kg 4,424 kg 1,225 kg 238 kg
Empty Mass 1,900 kg 695 kg 294 kg 30 kg
Thrust 470 kN 259 kN 60.5 kN 12.4 kN
Isp 214 s (2.10 kNs/kg) 262 s (2.57 kNs/kg) 256 s (2.51 kNs/kg) 256 s (2.51 kNs/kg)
Burn time 40 s 37 s 39 s 38 s
Length 9.12 m 6.04 m 3.38 m 1.83 m
Diameter 1.01 m 0.79 m 0.78 m 0.46 m
Engine: Aerojet General Algol 1 Thiokol XM33 (TX-354-3) Castor 2 Allegany Ballistics Lab X-254 Antares 1A Allegany Ballistics Lab X-248 Altair 1
Propellant Solid Fuel Solid Fuel Solid Fuel Solid fuel
LEO payload

XRM-91 Blue Scout Junior / Journeyman B (USAF)

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.[27] 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; this provided a reliable and survivable emergency communications method for the United States National Command Authority, using a UHF repeater that would transmit pre-recorded messages to all units within line-of-sight of the rocket's apogee.[28]

NASA used a three-stage Blue Scout Junior configuration (omitting the Cetus 4th stage) as the RAM B.

San Marco Project

See also: San Marco programme and Broglio Space Centre

The Italian space research program began in 1959 with the creation of the CRA (Centro Ricerche Aerospaziali) at the University of Rome. Three years later, on 7 September 1962, the university signed a memorandum of understanding with NASA to collaborate on a space research program named San Marco (St. Mark). The Italian launch team was trained by NASA. The San Marco project was focused on the launching of scientific satellites by Scout rockets from a mobile rigid platform located close to the equator. This station, composed of 3 oil platforms and two logistical support boats, was installed off the Kenya coast, close to the town of Malindi.


Main article: List of Scout launches


The Scout rockets have contributed to several pieces of debris over the years, some of which is still orbiting as of 2023.[29]

See also


  1. ^ "Scout". Archived from the original on December 27, 2016. Retrieved 13 May 2020.
  2. ^ "Scout Launch Vehicle Program". NASA. Archived from the original on 2016-11-10. Retrieved 2005-08-07.
  3. ^ "Scout". The Satellite Encyclopedia.
  4. ^ "Scout G". Encyclopedia Astronautica. Archived from the original on May 2, 2002.
  5. ^ a b "Miniature Sensor Technology Integration MSTI series". NASA. Retrieved 6 January 2016.
  6. ^ "MSTI 2". Skyrocket. Retrieved 6 January 2016.
  7. ^ a b "NASA'S SCOUT LAUNCH VEHICLE". NASA GSFC. Archived from the original on 2008-05-10.
  8. ^ "LTV SLV-1 Scout".
  9. ^ Ley, Willy (December 1967). "Astronautics International". For Your Information. Galaxy Science Fiction. pp. 110–120.
  10. ^ Yenne, Bill (1985). The Encyclopedia of US Spacecraft. Exeter Books (A Bison Book), New York. ISBN 0-671-07580-2.p.12 AEROS
  11. ^ "Transit". Encyclopedia Astronautica. Archived from the original on June 24, 2002.
  12. ^ "Transit 5A - NSSDC ID: 1962-071A". NASA NSSDC.
  13. ^ "Transit-O 31- NSSDC ID: 1988-074B". NASA NSSDC.
  14. ^ "Gunter's Space Page FR 1".
  15. ^ Krebs, Gunter (March 5, 2017). "Scout Family". Retrieved July 1, 2017.
  16. ^ "Scout-X1A". Gunter's Space Page. Retrieved 2024-04-06.
  17. ^ Mark Wade. "Scout X-2". Archived from the original on December 27, 2016. Retrieved March 1, 2020.
  18. ^ "P35 2 - NSSDC ID: 1962-039A". NASA NSSDC.
  19. ^ Shaltanis, Capt Dan A. "Defense Meteorological Satellite Program History". Archived from the original on 2008-07-20.
  20. ^ "Scout-X3". Gunter's Space Page. Retrieved 2024-04-06.
  21. ^ Mark Wade. "Scout X-4". Archived from the original on December 27, 2016. Retrieved March 1, 2020.
  22. ^ "Scout-A1". Gunter's Space Page. Retrieved 2024-04-06.
  23. ^ "Scout-B1". Gunter's Space Page. Retrieved 2024-04-06.
  24. ^ "Scout-D1". Gunter's Space Page. Retrieved 2024-04-06.
  25. ^ "Scout-F1". Gunter's Space Page. Retrieved 2024-04-06.
  26. ^ "Scout-G1". Gunter's Space Page. Retrieved 2024-04-06.
  27. ^ Scout information sheet at (accessed 2008-10-22)
  28. ^ Parsch, Andreas. Ford MER-6 Blue Scout., 9 July 2007. Accessed 2020-04-30.
  29. ^ "NSYO Database search for SCOUT". Retrieved 22 February 2023.

Krebs, Gunter Dirk. "Scout Family". Gunter's Space Page. Retrieved 2024-06-15.