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Vanguard TV3 Backup



The Vanguard Test Vehicle 3 Backup (TV-3 BU) failed less than one minute after launch on 5 February 1958. The satellite was, as the name implies, built as a backup to the Vanguard TV-3 satellite, which was launched unsuccessfully on 6 December 1957. The main purpose of the Vanguard Test Vehicle launchings was systems testing for the launch vehicle and satellite. The program objectives for the satellite were to conduct micrometeorite impact and geodetic measurements from Earth orbit. Engineering studies included electron charge and temperature of the satellite. The IGY Vanguard satellite program was designed with the purpose of launching one or more Earth orbiting satellites during the International Geophysical Year (IGY), which ended on 31 December 1958.

Mission Profile

Launch took place on 5 February 1958 at 07:33 UT from the Atlantic Missile Range in Cape Canaveral, Florida. Initial launch was nominal, but at an altitude of 460 meters (1500 ft) a malfunction in a connection between units of the control system or in the first stage servo amplifier resulted in loss of attitude control. Spurious electrical signals caused motion of the first stage engine in the pitch plane. At an altitude of about 20,000 feet (6.1 km), 57 seconds into the flight, a violent pitch-down to 45 degrees resulted in excessive structural and air loads on the launch vehicle, which broke up at the aft end of the second stage at 62 seconds, ending the mission.

Spacecraft and Subsystems

The satellite was identical to the TV-3 satellite, an approximately 1.5-kg aluminum sphere 16.3 cm in diameter, nearly identical to the later Vanguard 1. A cylinder lined with heat shields mounted inside the sphere held the instrument payload. It contained a set of mercury-batteries, a 10-mW, 108-MHz telemetry transmitter powered by the batteries, and a 5-mW, 108.03-MHz Minitrack beacon transmitter, which was powered by six square (roughly 5 cm on a side) solar cells mounted on the body of the satellite. Six 30-cm long, 0.8-cm diameter spring-actuated aluminum alloy aerials protruded from the sphere. On actuation, the aerial axes were mutually perpendicular on lines that passed through the center of the sphere. The transmitters were primarily for engineering and tracking data, but were also to determine the total electron content between the satellite and ground stations. Vanguard also carried two thermistors which could measur the interior temperature in order to track the effectiveness of the thermal protection.

A cylindrical separation device was designd to keep the sphere attached to the third stage prior to deployment. At deployment a strap holding the satellite in place would be released and three leaf springs would separate the satellite from the cylinder and third stage at a relative velocity of about 0.3 m/s.

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

  • VanguardTV3Backup

Facts in Brief

Launch Date: 1958-02-05
Launch Vehicle: Vanguard
Launch Site: Cape Canaveral, United States
Mass: 1.5 kg

Funding Agency

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


  • Communications

Additional Information

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



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