Energetic Particles: Acceleration, Composition and Transport (EPACT) Investigation on WIND

The main purpose of the Wind spacecraft is to measure the incoming solar wind, magnetic fields and particles, although early on it will also observe the Earth's foreshock region. Wind, together with Geotail, Polar, SOHO, and Cluster projects, constitute a cooperative scientific satellite project designated the International Solar Terrestrial Physics (ISTP) program which aims at gaining improved understanding of the physics of solar terrestrial relations. The Energetic Particles: Acceleration, Composition and Transport (EPACT) investigation is designed to make comprehensive observations of solar, interplanetary, and galactic particles over wide ranges of charge, mass, and intensity using a combination of 8 different particle telescopes. Energetic particles are electrons or ions of all the chemical elements that have been accelerated to speeds of one tenth of the speed of light or more. These particles are accelerated in solar flares and at shock waves driven out from the Sun by fast coronal mass ejections (CMEs). They are accelerated in planetary magnetospheres and bow shocks and at the heliospheric termination shock where the solar wind runs into interstellar material (these latter particles are called anomalous cosmic rays (ACRs). The galactic cosmic rays (GCRs) are accelerated by shock waves from distant supernovae. EPACT data is available from the Polar-Wind-Geotail (PWG) Data Archive ( ftp://pwgdata.gsfc.nasa.gov/pub/00readme.html ) and at the NSSDC CDAWeb ( http://cdaweb.gsfc.nasa.gov/cdaweb/ )