U.S. observes 50 years of spaceflight

The launch of the first U.S. satellite, Explorer I, atop a U.S. Army Jupiter C Rocket on Jan. 31, 1958. (U.S. Air Force photo)

The launch of the first U.S. satellite, Explorer I, atop a U.S. Army Jupiter C Rocket on Jan. 31, 1958. (U.S. Air Force photo)

SCHRIEVER AIR FORCE BASE, Colo. -- Jan. 31 marks the 50th anniversary of the first U.S. launch of a satellite into space. In October 1957, the Soviet Union launched Sputnik I, the first man-made object to orbit the Earth. On the day the Soviets launched Sputnik, then-Secretary of Defense Neil McElroy was visiting the Redstone Arsenal in Huntsville, Ala. Army Gen. John B. Medaris and Dr. Wernher von Braun used the event to push for a U.S. satellite launch. Secretary McElroy directed the Army Ballistic Missile Agency to prepare a rocket to place a satellite into orbit within 90 days. 

The U.S. rocket carried the Explorer scientific satellite as part of the United States' participation in the International Geophysical Year. The IGY coincided with the 11-year solar cycle, and scientists hoped to measure sunspots' effects on the aurora. They also hoped to study cosmic rays, gravity, meteorology, seismology, and other Earth sciences. Explorer I contained instruments to measure cosmic rays outside the atmosphere. 

Dr. James Van Allen, a professor of Applied Physics and Dr. George Ludwig at the University of Iowa developed the Explorer I instrumentation. While Van Allen, Dr. Ludwig and Dr. William Pickering of the Jet Propulsion Laboratory in California assembled the satellite, Dr. von Braun modified an Army Redstone rocket into the Juno I launch vehicle to carry the satellite. In December 1957, while Dr. von Braun and his team tested the systems for Juno I, the U.S. Navy tried to launch the Vanguard satellite. However, Vanguard exploded on the launch stand at Cape Canaveral Air Force Station, Fla. 

Juno I lifted off Jan. 31, 1958, from Launch Complex 26 at Cape Canaveral and placed Explorer I into orbit. Dr. von Braun, Dr. Van Allen, Ludwig Dr. and Dr. Pickering accomplished this feat in 84 days. Explorer I returned an enormous amount of data on the radiation belt around the Earth, later named the Van Allen Belt. 

Explorer I stopped transmission of data May 23 when its batteries died, but it remained in orbit for more than 12 years. It made a fiery reentry over the Pacific Ocean March 31, 1970. After Explorer I, Dr. von Braun led the U.S. civilian space program at NASA, including the Mercury, Gemini and Apollo manned missions; while Dr. Van Allen helped on other space exploration satellites such Pioneer and Mariner deep-space probes. But it was their efforts on Explorer I that made a great start for the United States at the beginning of the space race.