Vanguard 2: NASA’s First Successful Satellite Launch

A key component of NASA’s infant space science program was Project Vanguard. Originally developed by the Naval Research Laboratory (NRL) as America’s first official satellite program (see “Vanguard TV-3: America’s First Satellite Launch Attempt” ), Project Vanguard and much of its NRL team were transferred to NASA once it was established in October 1958 along with most other science-oriented space projects run by the Department of Defense.

Despite a dismal orbital launch record of only one success in seven tries by the time NASA assumed control, it was recognized that Project Vanguard was at the cutting edge of space science and technology. As a result, Project Vanguard had much to offer future NASA programs in the way of experience and technology. But in addition to this, Project Vanguard also arrived with a ready supply of hardware consisting of four three-stage launch vehicles in flight-ready condition and an assortment of scientific satellite payloads just waiting to be launched.

Vanguard 2

After the string of four failures that followed the launch of Vanguard 1 in March of 1958, the project team and its industrial partners had much work ahead of them to improve the reliability of the Vanguard launch vehicle (see “Vanguard 1: The Little Satellite That Could”). After a five month stand down, the former-NRL team was ready to launch their first satellite under NASA management. By early 1959, the components of SLV-4 (Satellite Launch Vehicle 4) had been exhaustively tested and assembled at Launch Complex 18A at the Eastern Test Range in Florida.

Diagram showing the configuration of the Vanguard 2 satellite. (NASA)

The payload for this launch vehicle would be one of the project’s “standard” satellites consisting of a polished, 51-centimeter magnesium alloy sphere holding a pair of transmitters, recorders, scientific instruments, and mercury batteries to power it all (see “Vintage Micro: The First Standardized Microsatellite”). For this particular mission, the primary instrument was a pair of small telescopes equipped with infrared-sensitive photocells designed to produce the first images of Earth from orbit for a period of two weeks. Supplied by the Army Signal Corps which was developing a weather satellite under the aegis of ARPA (Advanced Research Projects Agency), these units would use the spin of the satellite to scan a line across the face of the Earth. The forward motion of the satellite would then allow a picture of the scene below to be produced one line at a time. The spot covered by the photocell was expected to be about 11 kilometers across when viewing at nadir at perigee (over a factor of ten coarser than the resolution typically provided by today’s weather satellites) and about 80 kilometers at the expected apogee altitude.

Photograph of the pair of photocell-equipped telescopes carried by Vanguard 2. (NASA)

Diagram showing the optical configuration (left) and detector head (right) for the Vanguard 2 experiment. Click on image to enlarge. (NASA)

Each of the photocell-equipped telescopes in this experiment were triggered automatically by their own “solar battery” light sensor so that the instruments would only activate when the Earth below was in sunlight. The measured light intensities would be recorded using an onboard recorder with 23 meters of magnetic tape capable of holding up to 50 minutes of measurements. When the Vanguard satellite was within range of a ground station, Vanguard’s command receiver could activate the tape playback with all of its data transmitted in 60 seconds. This payload was virtually identical to that carried by the ill fated SLV-3 launched on September 26, 1958 just before NASA assumed control of the project. As before, it was hoped that these first crude images of the Earth from orbit would provide data on the planet’s radiation budget as well as guidance in designing more capable imaging systems in the future.

Final assembly of the Vanguard 2 satellite. (NASA)

At 10:55 AM EST (15:55 GMT) on February 17, 1959, SLV-4 smoothly lifted off and headed towards space. Once the third and final stage had burned out, the 10.8-kilogram Vanguard 2 was in a 557 by 3,319 kilometer orbit inclined 32.9° to the equator. After a string of three unsuccessful Moon probes (see “The First Race to the Moon: Getting Off the Ground”), NASA finally had its first successful launch into space.

The launch of Vanguard 2 from LC-18A at Cape Canaveral on February 17, 1959. (NASA)

But everything was not totally well with the Earth’s newest artificial companion. According to the original plan, a clamp holding Vanguard 2 to its solid propellant third stage was to release once in orbit allowing a spring to cleanly separate the two. While this took place more or less as planned, a residual discharge or “burp” from the free flying third stage rocket motor just after separation resulted in the stage bumping the released satellite. Instead of spinning predictably about a predetermined axis, the minor collision introduced a precession that set Vanguard 2 wobbling as it traveled around the Earth.

A photograph of Vanguard 2 in orbit acquired by the Smithsonian’s Baker-Nunn telescopic camera in Woomera, Australia on February 19, 1959. (NASA)

Without a means of determining exactly where it was pointing, the stream of brightness values returned by Vanguard 2 could not be reassembled into a coherent picture by scientists back on the ground. While certainly a disappointment to the experiment’s designers, the data Vanguard 2 returned during its 27-day active life was still quite useful. Analysis of the data yielded some information on scene contrast and illumination as observed from orbit. All this information would aid the development of future weather satellites (see “The First Weather Satellite”). The long-silent Vanguard 2 and its launch vehicle’s upper stage remain in orbit to this day and are expected to stay there for another couple of centuries.

More Vanguard Launches

With the successful launch of Vanguard 2, attention turned to the next satellite. Unlike the simple satellites carried earlier, the payload for SLV-5 had an entirely different configuration. Provisionally dubbed “Vanguard 3”, this 10.6 kilogram payload actually consisted of a pair of satellites. The first, Vanguard 3A, was a 33-centimeter in diameter fiberglass and phenolic resin sphere carrying a precision magnetometer designed to map the Earth’s magnetic field.

The satellite payload, designated “Vanguard 3A”, carried by the Vanguard SLV-5 rocket. (NASA)

Connected to Vanguard 3A by a 6.4 centimeter wide, 44.5 centimeter long cylinder was a second satellite designated Vanguard 3B. This passive satellite was a laminated sheet plastic and aluminum foil balloon that would inflate to 76 centimeters across after it separated from Vanguard 3A in orbit. Lacking a transmitter or other active instrumentation, Vanguard 3B would be tracked optically to yield information on the density of the uppermost reaches of Earth’s atmosphere.

The 76-cm balloon payload, designated “Vanguard 3B”, also carried by the SLV-5 rocket. (NASA)

While this multiple satellite technique was an innovative means of making the best use of a rocket’s payload capability (one that NRL engineers would put to extensive use in future Navy satellite programs), Vanguard 3 would never have a chance to prove itself. SLV-5 failed during ascent on April 13, 1959 when pitch control was lost in the second stage of the launch vehicle after its first stage had separated. Following this disappointing failure, NASA canceled the lost payload’s “Vanguard 3” designation in an attempt to establish the agency’s early practice of saving official satellite designations (like “Vanguard”, “Pioneer”, and “Explorer”) for payloads that survived launch and actually made it into space. The “Vanguard 3” moniker would be reserved for the next Vanguard satellite to reach orbit.

The Vanguard SLV-6 rocket waiting for launch from LC-18A. (NASA)

The next Vanguard rocket, SLV-6, was earmarked to launch the next “Vanguard 3” contender. Unlike the unique configuration of the previous payload, a standard Vanguard satellite would be launched this time. This 10.8 kilogram satellite was to be placed into a high inclination, 48° orbit in order to measure the Earth’s radiation budget over a large fraction of its surface. Instruments on the satellite, developed by Verner Suomi of the University of Wisconsin (widely considered the “Father of Satellite Meteorology”), would measure the amount of incoming light from the Sun, the reflected light from the Earth, as well as the amount of infrared radiation emitted by the Earth’s surface and atmosphere. Such information would be vital in developing more advanced and accurate models of Earth’s weather and climate.

Verner Suomi (left) and his collaborator, electrical engineer Robert Parent, shown with a Vanguard satellite equipped with the Earth radiation budget experiment they developed. (NOAA)

Because of the high inclination of the intended orbit, SLV-6 would have to perform an untried roll maneuver shortly after launch to set it on the more northerly course required for this mission. On June 22, 1959 SLV-6 lifted off and successfully rolled from its initial azimuth of 48° to 100° before pitching over as planned. But as had happened too often before, things went awry after the second stage took over. Immediately after ignition of the second stage’s AJ-10 engine, pressure plummeted in the second stage’s tanks resulting in a reduced propellant flow. After the AJ-10 sputtered for 40 seconds, the helium pressurant tank exploded because of the heat build up destroying the ascending rocket. Vanguard had failed again. NASA had just one Vanguard launch vehicle left before finishing the program before year’s end.

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General References

J. S. Buts, Jr., “Vanguard II Maps Earth’s Cloud Cover”, Aviation Week, Vol. 70, No. 8, pp 31-32, February 23, 1959

James Fusca, “U.S. Designs Infrared-Scanner Satellite”, Aviation Week, Vol. 69, No. 7, pp 82-87, August 18, 1958

John P. Hagen, “The Viking and the Vanguard”, in The History of Rocket Technology, edited by Eugene M. Emme, Wayne State University Press, pp. 122-141, 1964

Constance McLaughlin Green and Milton Lomask, Project Vanguard: The NASA History, Dover Publications, 2009