Spaceflight Insider

Our Spaceflight Heritage: Vanguard 3

Image Credit: NASA

On September 18, 1959, the Vanguard 3  satellite was launched on a Vanguard rocket from Cape Canaveral Air Force Station’s Space Launch Complex 18 (LC-18) in Florida. The United States Department of the Navy successfully launched the third of eleven Vanguard satellites from the Eastern Test Range into geocentric orbit.

The primary objective of the flight was to measure the Earth’s magnetic field, solar X-ray radiation and its effects on the Earth’s atmosphere, and the near-earth micrometeoroid environment.

Four experiments were returned to Earth after Vanguard 3 completed its orbital mission:

Sketch of the Vanguard 3 satellite. Image Credit: NASA History

Sketch of the Vanguard 3 satellite. Image Credit: NASA History

Proton Precessional Magnetometer: This experiment was housed in a glass fiber phenolic resin conical tube which was attached to the sphere of Vanguard 3. Under the principal investigation of Dr. James P. Heppner, this experiment had a proton magnetometer to measure the earth’s magnetic field between an altitude of 514 to 3714 km and latitudes around 33.4 degrees. When switched on by command, the spacecraft passed seven tracking stations between Australia and South Africa,the polarization coil around the proton same was turned on for two seconds. The experiment was active for 85 days after transmission stopped on December 11, 1959.

X-Ray Experiment: Under the direction of Dr. Herbert D. Friedman, the main objective of this experiment was to measure X-ray emissions from the Sun and its effects on the Earth’s atmosphere.

Micrometeorite: Led by Dr. Herman E. Lagow, this experiment was designed to record the impact of micrometeorites large enough to pierce the satellite shell. A puncture in the walls of the two sealed pressure zones was detected by a pressure gauge mounted between them. Erosion of the shell by dust, micrometeorites, and other particles were recorded by three chromium-strip gauges mounted on Vanguard 3‘s surface. Electrical resistances of the gauges changed as their surfaces were changed by erosion.

Satellite Drag Atmospheric Density: As principal investigator, Dr. Luigi G. Jacchia selected Vanguard 3 for use in determining the upper atmospheric densities as a function of altitude, latitude, season, and solar activity. This was not a planned experiment before launch.

The collected data that was obtained provided a comprehensive survey of the Earth’s magnetic field over the area covered, defined the lower edge of the Van Allen radiation belt, and provided a cont of micrometeorite impacts. After the scientific mission ended, the spacecraft and two pieces of its upper stage have remained in orbit. Vanguard 3 has an orbital lifetime of 300 years.


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Heather Smith's fascination for space exploration – started at the tender age of twelve while she was on a sixth-grade field trip in Kenner, Louisiana, walking through a mock-up of the International Space Station and seeing the “space potty” (her terminology has progressed considerably since that time) – she realized at this point that her future lay in the stars. Smith has come to realize that very few people have noticed how much spaceflight technology has improved their lives. She has since dedicated herself to correcting this problem. Inspired by such classic literature as Anne Frank’s Diary, she has honed her writing skills and has signed on as The Spaceflight Group’s coordinator for the organization’s social media efforts.

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