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Vanguard SLV 3



Vanguard Satellite Launching Vehicle 3 (SLV-3) was launched on 26 September 1958. The second stage failed to achieve the minimal performance necessary to maintain Earth orbit, and the spacecraft re-entered the atmosphere and burned up. The objective of the satellite was to scan Earth's cloud cover from orbit. The purpose of the IGY Vanguard satellite program, run by the U.S. Navy, was to launch one or more satellites into Earth orbit during the International Geophysical Year (IGY).

Mission Profile

Vanguard SLV-3 was launched from the Atlantic Missile Range in Cape Canaveral, Florida, on 26 September 1958 at 15:38 UT. Flight was nominal during the liftoff period, but the performance of the second stage was below the anticipated minimum requirement. The third stage fired as planned, although separation from the second stage occurred about 50 seconds early, at 422.7 seconds after launch. The failure of the second stage resulted in a final velocity that was about 75 meters per second (250 feet per second) short of the roughly 7500 mps (25,000 fps) required to reach the planned orbit. The burned out third stage and satellite reached an altitude of almost 425 km (265 miles) before coming back down and burning up on re-entry into the atmosphere. This was believed to have occurred over Central Africa after completion of one orbit. The poor performance of the second stage was concluded to be a result of low fuel flow rate due to contamination from Buna-N rubber particles from the helium fill hose.

Spacecraft and Subsystems

The SLV-3 satellite was a 10.6 kg (23.3 lb), 50.8 cm (20 inch) diameter magnesium sphere. The interior was pressurized. The payload instrumentation package was mounted in the center of the sphere. The package was arranged in a cylindrical stack with mercury batteries at the bottom, followed by the minitrack tracking system electronics, the environment electronics, the telemetering instrumentation, and the experiment electronics. Below the package at the bottom of the sphere was the separation device, a spring loaded tube with a timer designed to push the satellite away from the third stage after orbit was reached. At the top of the interior of the sphere was a pressure gauge. Four 30-inch spring-loaded metal rods were folded along the equator of the sphere and would protrude radially outward when deployed, acting as a turnstile antenna. It used two transmitters: a 10 mW transmitter broadcasting at a frequency of 108.00 megahertz and a 1 W transmitter broadcasting at 108.03 megahertz. The payload contained two infrared-sensitive photocells designed to scan the cloud cover of Earth.

Launch Vehicle

Vanguard was the designation used for both the launch vehicle and the satellite. The first stage of the three-stage Vanguard Test vehicle was powered by a GE X-405 28,000 pound (~125,000 N) thrust liquid rocket engine, propelled by 7200 kg of kerosene (RP-1) and liquid oxygen, with helium pressurant. It also held 152 kg of hydrogen peroxide. It was finless, 13.4 m (44 ft.) tall, 1.14 m (45 in.) in diameter, and had a launch mass of approximately 8090 kg (17,800 lbs. wt.).

The second stage was a 5.8 m (19 ft.) high, 0.8 m (31.5 in.) diameter Aerojet-General AJ-10 liquid engine burning 1520 kg (3350 lbs) Unsymmetrical Dimethylhydrazine (UDMH) and White Inhibited Fuming Nitric Acid (WIFNA) with a helium pressurant tank. It produced a thrust of 7340 pounds (~32,600 N) and had a launch mass of approximately 1990 kg (4390 lbs. wt.). This stage contained the complete guidance and control system.

A solid-propellant rocket with 2350 pounds (~ 10,400 N) of thrust (for 30 seconds burn time) was developed by the Grand Central Rocket Co. to satisfy third-stage requirements. The stage was 1.5 m (60 in.) high, 0.8 m (31.5 in.) in diameter, and had a launch mass of 194 kg (428 lbs.). The thin (0.076 cm, 0.03 in.) steel casing for the third stage had a hemispherical forward dome with a shaft at the center to support the satellite and an aft dome fairing into a steel exit nozzle.

The total height of the vehicle with the satellite fairing was about 21.9 meters (72 feet). The payload capacity was 11.3 kg (25 lbs.) to a 555 km (345 mi.) Earth orbit. A nominal launch would have the first stage firing for 144 seconds, bringing the rocket to an altitude of 58 km (36 mi), followed by the second stage burn of 120 seconds to 480 km (300 mi), whereupon the third stage would bring the satellite to orbit. This was the same launch vehicle configuration, with minor modifications, as used for Vanguard TV-3 and all succeeding Vanguard flights up to and including Vanguard SLV-6.

Alternate Names

  • VanguardSLV3

Facts in Brief

Launch Date: 1958-09-26
Launch Vehicle: Vanguard
Launch Site: Cape Canaveral, United States
Mass: 10.6 kg

Funding Agency

  • Department of Defense-Department of the Navy (United States)


  • Space Physics
  • Earth Science

Additional Information

Questions and comments about this spacecraft can be directed to: Dr. David R. Williams



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