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Image of Explorer 1 spacecraft.
NASA/JPL

Explorer

Explorer 1, launched on Jan. 31, 1958, was the first U.S. satellite to orbit the Earth. Its successful flight made the United States the second nation in space, following the Soviets who had launched Sputnik 1 just four months earlier.

Explorer 1 carried several scientific instruments which measured space temperature and the dangers of small meteorites. Its major accomplishment was the discovery of an area of radiation which surrounds the Earth.

Between 1958 and 1981 there were 56 more Explorer spacecrafts to reach space. Each was small, relatively inexpensive, and carried out a variety of scientfific missions.


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Sputnik

The Soviet Sputnik program consisted of four satellites, three of which reached Earth orbit. Sputnik 1, launched on Oct.4, 1957, became the first artificial satellite to successfully orbit the Earth. It...more

The Discovery of the Radiation Belts

In 1957, Russia launched Sputnik 1, the first spacecraft to ever be launched. Americans wanted to send up a satellite too. They sent up Explorer I. Even though this was America's first satellite, Explorer...more

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Hubble Space Telescope

The Hubble Space Telescope (HST) is really neat! It was first launched in 1990, but scientists started building it in the 1970's! We have found all kinds of objects like stars, nebulae and galaxies. The...more

Apollo 11

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Apollo 12

Apollo 12 was launched on Nov. 14, 1969 and arrived at the Moon three days later. Astronauts Charles Conrad and Alan Bean descended to its surface, while Richard Gordon remained in lunar orbit aboard the...more

Apollo 15

Apollo 15 marked the start of a new series of missions from the Apollo space program, each capable of exploring more lunar terrain than ever before. Launched on July 26, 1971, Apollo 15 reached the Moon...more

Windows to the Universe, a project of the National Earth Science Teachers Association, is sponsored in part is sponsored in part through grants from federal agencies (NASA and NOAA), and partnerships with affiliated organizations, including the American Geophysical Union, the Howard Hughes Medical Institute, the Earth System Information Partnership, the American Meteorological Society, the National Center for Science Education, and TERC. The American Geophysical Union and the American Geosciences Institute are Windows to the Universe Founding Partners. NESTA welcomes new Institutional Affiliates in support of our ongoing programs, as well as collaborations on new projects. Contact NESTA for more information. NASA ESIP NCSE HHMI AGU AGI AMS NOAA