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2049569 
Journal Article 
SAMPEX: A Long-Serving Radiation Belt Sentinel 
Baker, DN; Blake, JB 
2012 
Yes 
Geophysical Monographs Book Series
ISSN: 0065-8448 
Geophysical Monograph Series 
199 
21-40 
WOS:000321935300003 
The near-Earth region of the magnetosphere responds powerfully to changes of driving forces from the Sun and the solar wind. The Earth's radiation belts and inner magnetosphere show substantial differences in their characteristics as the Sun's magnetic field and solar wind plasma properties change over the approximately 11 year solar activity cycle. Solar coronal holes produce regular, recurrent fast solar wind streams in geospace, often enhancing highly relativistic electrons and causing recurrent geomagnetic storms. These phenomena are characteristic of the approach to sunspot minimum On the other hand, major geomagnetic disturbances associated with aperiodic coronal mass ejections occur most frequently around sunspot maximum. Such disturbances also can often produce significant radiation belt enhancements. We describe the observational results that characterize the differences throughout the inner part of geospace during the course of the solar activity cycle. We place particular emphasis on long-term, homogeneous data sets from the Solar, Anomalous, and Magnetospheric Particle Explorer (SAMPEX) mission. The NASA SAMPEX spacecraft launched in 1992 is expected to end its mission by December 2012. This space platform has revolutionized our views of the dynamic radiation belt environment. We conclude that SAMPEX has been a most successful and impactful mission for radiation belt studies.