Cosmic Ray and Solar Particle Investigation

The COsmic ray and Solar Particle INvestigation (COSPIN) instrumentation on Ulysses consists of a group of six charged particle telescopes to measure the energy, composition, intensity and anisotropy of nucleons in the energy range from ~ 0.5 MeV/nucleon to ~ 600 MeV/nucleon for elements in the range H to Ni. Isotopic abundances for nuclei H to Ni are obtained over a more limited energy range. Electron measurements extend from 2.5 to 6000 MeV. One set of telescopes measures the three-dimensional anisotropies of protons and helium at low energies. A special high flux telescope provides measurements of protons and heavier particles ~ 0.2 to ~ 36 MeV with high azimuthal resolution. These instruments were prepared by an international consortium to address a wide range of scientific objectives made possible by a mission to investigate the Sun and the heliosphere in three dimensions.

Examples of the COSPIN scientific goals include: (i) For energetic charged particles of solar origin, to determine the role of coronal magnetic fields in their acceleration and propagation, to investigate their further acceleration and propagation through the 3-dimensional heliosphere, and to search for the origin of the enrichment of 3He and Fe nuclei observed in some solar particle events; (ii) Using galactic cosmic radiation measurements, to explore the variation of solar modulation with solar latitude as a function of the phase of the solar activity cycle, to search for the origin of the anomalous nuclear component, and to determine the nucleosynthetic origins of nuclei at lowest measurable energies through studies of isotopic abundances; (iii) For energetic nuclei and electrons of interplanetary origin, to study the three-dimensional character of traveling shocks, CIRs, CMEs, and their associated charged particle acceleration, and; (iv) As a secondary scientific objective at Jupiter encounter (closest approach 8 Feb., 1992), to characterize the energetic charged particle populations during the first traversal of the dusk side of the Jovian magnetosphere, to search for the mechanism producing the ~ 10 hour "clock" variation of Jovian electrons in the interplanetary medium, and to investigate the propagation of jovian electrons to high latitudes in the heliosphere.

As demonstrated by the papers listed in the COSPIN Bibliography on the COSPIN Home Page at the University of New Hampshire, all of these goals have been addressed and most continue to be addressed in the ongoing analysis of COSPIN observations from the Ulysses mission. Since its launch in 1990, Ulysses has provided measurements over more than half of the 22-year solar magnetic cycle, and it continues to provide observations critical to defining the evolution of the 3-dimensional distributions of the energetic particle populations in the heliosphere over the solar activity and magnetic cycles.

A complete description of the COSPIN instrumentation is given in J.A. Simpson et al., Astron. Astrophys. Suppl. Ser. 92, 365-399, 1992

COSPIN Home Page at the University of New Hampshire

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