dipper@utastro.UUCP (Debbie Byrd) (10/11/84)
This is the anniversary of the first Pioneer spacecraft. More on this series of spacecraft -- right after this. October 11 Pioneers in the Solar System On this date in the year 1958, the first of a valiant series of spacecraft was launched. It was called Pioneer I. In all, there have been eleven Pioneer spacecraft launched by NASA between 1958 and 1973. The series is complementary to flights by NASA's Mariner and Viking craft, which also added immensely to our knowledge about our immediate neighborhood of the solar system. The Pioneer spacecraft really are pioneers -- they explored an untouched realm of space. The first five Pioneers studied the sun's energy. They provided an early warning system for solar flares, whose effects can harm human beings while they journey in outer space. Data gathered by the first Pioneers ultimately helped protect U.S. astronauts on their way to the moon. Pioneer spacecraft also discovered that Earth has a magnetic tail -- a portion of its magnetic field which streams opposite the direction of the sun. And these craft measured the density of the solar wind, which consists of streams of ionized particles. The solar wind now is known to extend into the outer solar system. A Pioneer discovered that, too -- Pioneer 10, the first craft ever to visit Jupiter. Pioneer 10 is still moving outward. It's now beyond the orbits of Neptune, farther away than any earthly craft has ever gone. Pioneer 10 and its sister craft Pioneer 11 will also be the first to penetrate the unknown environment in the space between the stars, beyond the domain of the sun. Script by Deborah Byrd. (c) Copyright 1983, 1984 McDonald Observatory, University of Texas at Austin