Date: Beginning on March 17, 1958
Definition: The U.S. program to launch an artificial Earth satellite during the International Geophysical Year (1957-1958).
Significance: The explosion of the booster on the first Vanguard satellite launch, just two months after Sputnik 1 was placed in orbit, was a severe blow to American prestige. Later Vanguard satellites mapped the earth’s magnetic field and demonstrated infrared imaging of clouds.
The Beginning of the Vanguard Program
On July 29, 1955, James C. Hagerty, the White House press secretary, announced that the United States would launch small Earth-orbiting satellites as part ofits participation in the International Geophysical Year (IGY), an eighteen-month period running from July 1, 1957, to December 31, 1958, and dedicated to the scientific study of the earth. President Dwight D. Eisenhower decided not to use one of the military rockets then under development in the United States to launch America’s first satellite. A new rocket, to be called Vanguard, was to be developed for the American artificial satellite project.
The Vanguard Launch Vehicle
The Vanguard launch vehicle required the development of innovative technology. After a series of negotiations between the GlennL. Martin Company (GLM), which was to manufacture the rocket, and the Naval Research Laboratory (NRL), which managed the project for the U.S. government, the design was completed on February 29,1956.
The Vanguard launch vehicle was to be a three-stage rocket. The first two stages of Vanguard used liquid-propellant rocket engines, whereas the third stage used a solid-propellant engine. The first stage was based on the Navy’s Viking rocket, the second stage was a modified version of the Aerobee-Hi sounding rocket, and the third stage was developed specifically for the Vanguard project.
GLM had developed the Viking rocket, on which the design of the first stage of the Vanguard was derived, for the U.S. Navy in late 1940′s. The rocket engine, designed by General Electric (GE), produced 27,000 pounds of thrust. The first stage used kerosene as the fuel and liquid oxygen as the oxidizer. The fuel and oxidizer were delivered to the combustion chamber by an unusual system in which hydrogen peroxide decomposed producing steam, which drove the pumps, and oxygen.
The second stage of the Vanguard was derived from the Aerobee-Hi sounding rocket, built by Aerojet General Corporation. However, the Aerobee-Hi engine produced only four-fifths of the 7,500 pounds of thrust required for Vanguard, so the combustion chamber was redesigned to increase the thrust, and the fuel tanks were lengthened to carry more propellant. To save weight, the second stage carried the guidance system for both the first and the second stages, including a gyroscopic reference system used to ensure that the third stage was oriented so that it would fire along a path leading to an orbit. In addition, the second stage carried the mechanism to jettison the protective nose cone that shielded the satellite from the intense heat and air pressure during the launching phase ofthe flight. The second stage also carried a mechanism to spin the third-stage rocket, providing stability, and a device to detach the third stage from the second after burnout. The second stage also carried a radar beacon and receiver to cut off the fuel flow and detonate the rocket in case of a serious deviation from the planned flight path.
The third stage of the Vanguard was a solid-fuel rocket motor produced by Grand Central Rocket Company (GCR). It developed about 3,000 pounds of thrust. The takeoff weight of the three-stage Vanguard launch vehicle was about 22,600 pounds.
The Vanguard Satellite
The NRL developed the Vanguard satellite. Although GLM had favored using the rocket’s nose cone as the satellite, the NRL decided that the satellite would be spherical. One of the objectives of the Vanguard Program was to determine the atmospheric density at the orbital altitude of the satellite. The effects of air drag on a sphere in flight would be easier to measure than those on a cone-shaped body, making it easier to measure the density of the air. In addition, the National Academy of Sciences planned to use an optical tracking system, and a cone was more likely to tumble and be lost to sight. The National Academy of Sciences preferred a 30-inch-diameter spherical satellite,but 20 inches was the minimum diameter that could be easily tracked with the optical system. The NRL made the sphere of 0.020 aluminum with a 0.001 coating of aluminum oxide. The antennae were four wires that retracted during ascent of the launcher and released to spring outward after separation of the satellite from the burned-out third-stage rocket.
The Vanguard Flights
The first rocket in the Vanguard Program, designated TV 0, was launched from the Cape Canaveral Air Force Station in Florida, the site of all the Vanguard launches, on December 8, 1956. This launch was a test of the liquid-propellant first stage, a refurbished Viking rocket, Viking 13, left over from the Navy’s Viking test program. The purpose was to evaluate the performance of the telemetry system, the attitude control system, and the rocket engine.
The first attempt to launch the Vanguard satellite, onDecember6,1957, failed when the rocket exploded on the launch pad. (NASA)
The flight was a complete success. The rocket reached an altitude of 126.5 miles and impacted in the Atlantic Ocean about 97.6 miles from the launch site.
The second flight in the Vanguard Program, at wo-stage vehicle designated as TV 1, was launched onMay 1,1957. Vanguard TV 1 used the last of the leftover Viking rockets, Viking 14, which had been slightly modified, as its first stage. A solid rocket engine destined to become the third stage of the satellite launch vehicle was its second stage. The major objectives of TV 1 were to test the mechanism that would spin the solid rocket prior to separation and to test the separation and ignition mechanisms. TV 1 reached an altitude of 121 miles. This flight successfully tested the upper-stage rocket engine and the techniques used to separate the two stages in flight.
Vanguard TV 2 was launched on October 23, 1957. This rocket had the external appearance of the full Van- guard rocket, but only the first stage was a functioning rocket. The second and third stages had the same shape and weight of the real rockets, but they were inert. This was the first flight test of an actual Vanguard first stage, rather than a leftover Viking. The test was successful, reaching an altitude of 109 miles and flying 335 miles down the test range.
The first test of the full, three-stage Vanguard launch vehicle, designated as TV 3, occurred on December 6, 1957. Originally only a simple nose cone was to be carried on the TV 3 flight, but in July, 1957, it was decided that a small test satellite, weighing 3.25 pounds, would be carried to allow a test of the radio tracking stations that had been established around the world. The test satellite was simply a 6.4-inch-diameter sphere, made of aluminum and carrying two radio transmitters operating at frequencies near 108 megahertz.
The TV 3 flight was intended as an “all-up systems engineering test,” the major objective being to test the performance of all three stages of the Vanguard rocket. The launching of a satellite with minimal capabilities was a secondary objective. However, with the launch coming only two months after the Soviet Union had successfully launched Sputnik, the world’s first satellite, the world was watching this first American attempt to launch a satellite. The Vanguard TV 3 rocket exploded only two seconds after liftoff and collapsed back on the launching pad in an eruption of flames. The small satellite, recovered after the fire was extinguished, is now in the collection of the Smithsonian Institution in Washington, D.C.
Although the TV 3 backup vehicle, designated TV 3BU, was in the hangar when TV 3 exploded, damage to the launching pad from the TV 3 explosion delayed the flight of this next Vanguard rocket. The backup vehicle was launched on February 5, 1958. The first-stage engine performed well, but the control system of TV 3BU malfunctioned at an altitude of about 1,500 feet, 57 seconds into the flight, and the vehicle broke up.
The first successful satellite in the Vanguard Program, called Vanguard 1, was was launched by TV 4 on March 17, 1958. Vanguard 1 was a duplicate of the test satellites that TV 3 and TV 3BU had failed to launch. The 6.4-inch-diameter satellite, weighing only 3.25 pounds, was placed into an elliptical orbit. Its high point was 2,465 miles above the earth’s surface, and its low point was 406 miles above the earth’s surface. Vanguard 1 circled the earth once every 134 minutes. The objectives of the test satellite were to evaluate the performance of the solar cells that provided electrical power and to test the onboard transmitter and the worldwide tracking stations. The only instrument on Vanguard 1 was an internal temperature monitor.
The last of the Vanguard test vehicles, TV 5, was launched on April 28, 1958. This flight was the first that was designed to carry a full-size, 20-inch-diameter Vanguard satellite into orbit. The liftoff proceeded as planned, and the second stage fired normally. However, an electrical problem resulted in the failure of the third stage to separate and ignite, and the satellite fell into the ocean.
Following the test program, a series of Vanguard satellite launch vehicles (SLVs) were flown. The first flight, SLV 1, lifted off on May 27, 1958, carrying a 21.5-pound satellite. However, the launch vehicle failed at second-stage burnout, and the satellite failed to orbit.
SLV 2, carrying another 21.5-pound satellite, was launched on June 26, 1958, and again, the launch vehicle failed. SLV 3, launched on September 26, 1958, also carried a 21.5-pound satellite. The second-stage guidance system failed to provide proper pitch control, and the satellite completed less than one orbit of the earth before it re-entered the atmosphere.
With passage of the National Aeronautics and Space Act of 1958, the civilian National Aeronautics and Space Administration (NASA) was created to direct the U.S. space program. NASA took over management of the Vanguard Program in 1958. The first of the NASA-directed launchings, SLV 4, lifted off on February 17, 1959. All three stages fired properly, placing the Vanguard 2 satellite into orbit. Vanguard 2, which will remain in orbit for about 200 years, was the first of the 20-inch-diameter, fully instrumented Vanguard satellites to achieve orbit. Vanguard 2 weighed 20.7 pounds, carried the first instrument to photograph the earth from orbit, and radioed data to Earth for twenty-seven days. SLV 5, launched on April 13, 1959, failed to achieve orbit because of a problem with the separation of the second stage from the launch vehicle.
The last launch of the Vanguard program, SLV 6, used the refurbished TV 4BU backup vehicle. On September 18, 1959, SLV 6 placed the Vanguard 3 satellite into orbit. Vanguard 3 consisted of two spheres connected by a small cylinder. The weight of the satellite was 50.7 pounds. The larger sphere, measuring 20 inches in diameter, contained instruments that measured the micrometeorite impacts and solar radiation, while the smaller sphere, 13 inches in diameter, carried a magnetometer to map the earth’s magnetic field. Vanguard 3 transmitted until December 8, 1959.
Results of the Vanguard Program
Despite its small size, Vanguard 1 returned significant scientific results. Precise tracking of the orbital path of Vanguard 1 demonstrated that the earth is not a perfect sphere, but is slightly pear-shaped. Measurement of the air drag on Vanguard 1 demonstrated that the upper regions of the earth’s atmosphere were significantly more dense and more variable than previously suspected. Its solar cells proved so durable in the space environment that the transmitter continued to function until March, 1964.
Vanguard 2 obtained the first photographs of the earth from orbit, but the satellite wobbled so much that the photographs were blurred. Nontheless, Vanguard 2 pioneered the development of infrared-sensor technology, later used in the TIROS series of weather satellites to obtain infrared photographs of the earth’s cloud cover for use in weather forecasting.
Vanguard 3 accomplished its main task of mapping the earth’s magnetic field and measured the intensity of solar X rays.American embarrassment over the Vanguard TV 3 explosion on December 6,1957, drew attention to the Soviet lead in space exploration and initiated the space race. U.S. senator Lyndon B. Johnson called the failure “most humiliating,” and a New York Times headline noted that the failure to launch the test satellite was a blow to U.S. prestige. The American response led to an invigorated satellite-launching effort and the development of U.S. efforts at crewed spaceflight.
