  33. Vanguard 1, second American satellite launched. Information from Vanguard showed that the Earth is not quite round. The first artificial earth satellites were sometimes called “long-playing rockets” because they carried the same instruments and investigated the same problems as had the sounding rockets. The great advantage of the satellite was its ability to provide a continuous flow of information for long periods of time. The first science satellites were the forerunners of later vehicles that would demonstrate the direct benefits that satellites could offer to such varied fields as weather observation and communication. The advent of the earth satellite provided scientists with a new and valuable research tool. Science satellites have been used for such tasks as solar and astronomical observations, biology experiments, or atmospheric investigation. Explorer 1 (launched January 31, 1958) and Vanguard 1 (launched March 17, 1958), the first American earth satellites, carried scientific payloads into space. Project Vanguard’s important contributions to America’s space program were the creation of the minitrack tracking system, the first use of silicon solar cells for electric power in a satellite, as well as the discovery that Earth is not quite round. The Vanguard program drew to a close with the 1959 launch of Vanguard 3. This satellite studied variations in solar and x-ray radiation and the earth’s magnetosphere. It also determined air density in the upper atmosphere. The mysteries of the near-earth space environment drew Explorer 6, launched August 7, 1959. Explorer 6 instruments measured radiation levels in the Van Allen radiation belts, mapped the earth’s magnetic field, counted micrometeorites, and studied the behavior of radio waves in space. In addition, Explorer 6 carried a scanning device which returned the first complete television cloud-cover picture of the earth’s surface. 34. Artist’s concept of IMP-E. This satellite’s primary mission is to study solar wind and the interplanetary magnetic field at lunar distance and their interaction with the Moon. Explorer 10, launched on board a Thor-Delta rocket on March 25, 1961, confirmed the existence of the solar wind—the stream of particles that carries the Sun’s magnetic field beyond the orbit of Earth. During the satellite’s planned 52 hours in orbit, it relayed information on the relationship between terrestrial and interplanetary magnetic fields and the solar wind. To continue the study of solar wind and interplanetary magnetic fields, Explorer 12 was orbited by a Delta launch vehicle on August 16, 1961. It was the first in a series of satellites to study energetic particles in space. These electrons and protons constitute the earth’s radiation belts and they affect weather and other phenomena on Earth. Atmosphere Explorer-A was the first of NASA’s aeronomy satellites. It was designed to remain in operation three months, studying the composition, density, pressure, and temperature of the upper atmosphere. This satellite discovered a belt of neutral helium atoms around the Earth. Deriving its name from a spirit in Shakespeare’s play, The Tempest, Ariel 1 explored the ionosphere, a region of electrically charged air which begins about 40 kilometers (25 miles) above the surface of the Earth. Launched April 26, 1962, Ariel was a cooperative venture between Great Britain and the United States. It was both the first British satellite and NASA’s first international satellite. The Royal Society’s British National Committee on Space Research coordinated the experimental program; NASA scientists and technicians built the craft. Two small scientific laboratories, called Interplanetary Monitoring Platforms, were launched in 1967 to study the solar wind and other phenomena. IMP-E investigated interplanetary magnetic fields in the vicinity of the Moon. IMP-F investigated the interplanetary magnetic field also, in addition to the earth’s magnetosphere and radiation levels in space. Interplanetary space between the Earth and Venus was the subject area for Pioneer 5, launched March 11, 1960. The satellite tested long-range communications systems, developed methods for measuring astronomical distances, studied the effects of solar flares, and performed other tasks before it went into orbit around the Sun. With increasing interest in the earth’s space environment, a satellite was launched on September 7, 1967, to investigate the impact of space on biological processes. Biosatellite 2 was the second satellite in the program of three such vehicles. Frog eggs, plants, micro-organisms and insects were placed in orbit to enable scientists to study the combined effects of weightlessness, artificially produced radiation, and the absence of the normal day-night cycle on these organisms. Following two days in space, the capsule containing the experimental package reentered the atmosphere and was caught in mid-air by an Air Force recovery aircraft. Vanguard 1 is from John P. Hagan. Vanguard 3, Explorer 10, Explorer 12, AE-A, Ariel 1, IMP-E & F, and Biosatellite 2 are from the National Aeronautics and Space Administration. The models of Explorer 6 and Pioneer 5 are from Space Technology Laboratories. |
|
