Institute of Technology. NASA was not formally authorized by an act of Congress until the following October. Explorer 1 carried scientific instruments designed by Dr. James Van Allen of the University of Iowa. Circling Earth in an orbit ranging from 360 to 2,531 kilometers, the satellite radioed back radiation measurements, revealing a deep zone of radiation surrounding Earth.

Born of the technology of World War II and the tensions of the Cold War, the space age began in the peaceful pursuit of scientific discovery. In the more than 35 years that have followed, thousands of spacecraft have been launched into Earth orbit, to the Moon, and to the planets. For the majority of those spacecraft, the goal has been to learn about Earth, our solar system, and the universe.

Astrophysics
Just a few decades ago, the word astronomy was a general term that described the science of the planets, moons, Sun and stars, and all other heavenly bodies. In other words, astronomy meant the study of anything beyond Earth. Although still an applicable term, modern astronomy, like most other sciences, has been divided and subdivided into many specialities. Disciplines that study the planets include planetary geology and planetary atmospheres. The study of the particles and fields in space is divided into magnetospheric physics, ionospheric physics, and cosmic and heliospheric physics. The Sun has its own solar physics discipline. The origin and evolution of the universe is the subject of cosmology. Generally, objects beyond our solar system are handled in the field of astrophysics. These include: stars, the interstellar medium, other objects in our Milky Way Galaxy, and galaxies beyond our own.

NASA defines astrophysics as the investigation of astronomical bodies by remote sensing from Earth or its vicinity. Because the targets of the astrophysicist are generally beyond human reach even with our fastest rockets, astrophysicists concentrate solely on what the electromag-netic spectrum can tell them about the universe. NASA's astrophysics program has three goals: to understand the origin and fate of the universe, to describe the fundamental laws of physics, and to discover the nature and evolution of galaxies, stars, and solar system. The investigations of astrophysicists are carried out by instruments aboard free-flying satellites, sounding rockets that penetrate into space for brief periods, high-flying aircraft and high-altitude balloons, and Space Shuttle missions.

A Brief History of the United States Astronomy Spacecraft and Crewed Space Flights
The early successes of Sputnik and the Explorer series spurred the United States to develop long-range programs for exploring space. Once the United States was comfortable with the technical demands for spacecraft launches, NASA quickly began scientific studies in space using both crewed space flight and non-crewed satellite launches.

Teams of scientists began their studies in space close to home by exploring the Moon and the solar system. Encouraged by those successes they have looked farther out to nearly the beginning of the universe. Observing the heavens from a vantage point above Earth is not a new idea. The idea of placing telescopes in orbit came quite early--at least by 1923 when Hermann Oberth

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