... Explorers 1/3 . ... Orbit . ... Launch of Explorer 1 . ... The USSR was first, sending off its first "Sputnik" ("satellite") on October 4, followed by Sputnik II on November 3. ... The spacecraft, named Explorer 1, was launched 31 January 1958 and was designed and built by a group of scientists from the University of Iowa, led by James Van Allen . ... the launch of Explorer 1;Click . ... Explorer 2 failed to orbit, but Explorer 3, launched March 26, was successful, and it did carry a tape recorder. ...

... The motion of energetic ions and electrons through space is strongly constrained by the local magnetic field. The basic mode is rotation around magnetic field lines, while at the same time sliding along those lines, giving the particles a spiral trajectory. On typical field lines, attached to the Earth at both ends, such motion would soon lead the particles into the atmosphere, where they would collide and lose their energy. ... In this way the Earth holds on to its radiation belts. ...

... NASA Asteroid Orbiter . ... Launched on February 17, 1996, the Near Earth Asteroid Rendezvous (NEAR) mission is to be the first of NASA's Discovery missions, a series of small-scale spacecraft designed to proceed from development to flight in under three years for a cost of less than $150 million. ... The ultimate goal of the mission is to rendezvous with and achieve orbit around the near Earth asteroid 433 Eros in February, 1999, and study the asteroid for approximately one year. ...