cosmic ray component", which represents a sample of the local interstellar medium Origin of the elements and subsequent evolutionary processing Isotopic "anomalies" in meteorites indicate that the Solar System was not homogeneous when formed. Similarly, the Galaxy is neither uniform in space nor constant in time due to continuous stellar nucleosynthesis. ACE measurements have been used to: Search for differences between the isotopic composition of solar and meteoritic material Determine the contributions of solar wind and solar energetic particles to lunar and meteoritic material, and to planetary atmospheres and magnetospheres Determine the dominant nucleosynthetic processes that contribute to cosmic ray source material Determine whether cosmic rays are a sample of freshly synthesized material (e.g. from Supernova) or of the contemporary interstellar medium Search for isotopic patterns in solar and galactic material as a test of galactic evolution models Formation of the solar corona and acceleration of the solar wind Solar energetic particles, solar wind, and spectroscopic observations show that the elemental composition of the solar corona is differentiated from that of the photosphere, although the processes by which this occurs, and by which the solar wind is subsequently accelerated, are poorly understood. The detailed composition and charge–state data provided by ACE are used to: Isolate the dominant coronal formation processes by comparing a broad range of coronal and photospheric abundances Study plasma conditions at the source of solar wind and solar energetic particles by measuring and comparing the charge states of these two populations Study solar wind acceleration processes and any charge or mass-dependent fractionation in various types of solar wind flows Particle acceleration and transport in nature Particle acceleration is ubiquitous in nature and understanding its nature is one of the fundamental problems of space plasma astrophysics. The unique data set obtained by ACE measurements have been used to: Make direct measurements of charge and/or mass-dependent fractionation during solar energetic particle and interplanetary acceleration events Constrain solar flare, coronal shock, and interplanetary shock acceleration models with charge, mass, and spectral data spanning up to five decades in energy Test theoretical models for 3He–rich solar flares and solar γ–ray events Instruments Cosmic-Ray Isotope Spectrometer (CRIS) The Cosmic-Ray Isotope Spectrometer covers the highest range of the Advanced Composition Explorer's energy coverage, from 50 to 500 MeV/nucleon, with an isotopic resolution for elements from Z ≈ 2 to 30. The nuclei detected in this energy interval are predominantly cosmic rays originating in