Roger R. Anderson, J. Douglas Menietti, Robert W. Lane, and Mark
D. Brown, all at The University of Iowa, Department of Physics
and Astronomy, 615 Van Allen Hall, Iowa City, IA 52242 USA,
Phone: 319-335-1924, FAX:319-335-1753,
E-MAIL: roger-r-anderson@uiowa.edu
Mark B. Moldwin, Hamid K. Rassoul, and Paul Douglas, Florida
Institute of Technology, Physics and Space Sciences Department,
150 West University Boulevard, Melbourne, FL 32901-6988, USA,
E-MAIL: moldwin@pss.fit.edu
Donald L. Carpenter, STARLab, Stanford University, Department of
Electrical Engineering, 327 Durand, Stanford, CA 94305-4055,
E-MAIL: dlc@nova.stanford.edu
Michelle F. Thomsen, Space and Atmospheric Sciences, Los Alamos
National Laboratory, MS D466, Los Alamos NM, 87545,
E-MAIL: mthomsen@lanl.gov
In its nearly ten-year life following its launch on October 22, 1977, the International Sun Earth Explorer 1 (ISEE-1) with its 22.6 Re geocentric apogee, 700 km perigee altitude, and 30 degree inclination, made two passes, one outbound and one inbound, through the plasmasphere and magnetosphere every 57 hours. The Combined Release and Radiation Effects Satellite (CRRES), during its 15-month life after its launch on July 25, 1990, into a 6.3 Re geocentric apogee, 350 km perigee altitude, 18 degree inclination orbit, made an outbound and inbound pass through the plasmasphere and magnetosphere every 10 hours.
The ISEE-1 Plasma Wave Investigation (PWI) included a Sweep Frequency Receiver (SFR) that swept the frequency range from 100 Hz to 400 kHz every 32 seconds. The CRRES Plasma Wave Experiment (PWE) included a SFR that swept the frequency range from 100 Hz to 800 Hz every 32 seconds, the range from 800 Hz to 6.4 kHz every 16 seconds, and the range from 6.4 kHz to 400 kHz every eight seconds. Both these receivers provided measurements of the total electron density up to 2000 electrons/cc independent of spacecraft charging. Beyond the plasmapause in the outer magnetosphere the density was determined from the lower cutoff of the trapped continuum radiation at the local plasma frequency (Fpe) using the relation Fpe = 8.98 kHz x (Ne)**1/2 where Ne is in electrons/cc. Within the plasmasphere, emissions detected at the Upper Hybrid Resonance frequency, fUHR, were used to determine Ne via the relation Fuhr**2 = Fpe**2 + Fce**2 where the electron cyclotron frequency Fce = 28 Hz x |B(nT)|.
CRRES tended to cover the Earth's near-equatorial and low-latitude plasmasphere and magnetosphere out to geosynchronous orbit. The ISEE measurements primarily covered the mid-latitude region. These two spacecraft provided a comprehensive survey of the electron density in the magnetosphere as a function of location, time, and geomagnetic activity that are valuable data for generating and testing models of plasma dynamics. In analyzing the data, much variability and structure were observed frequently in the plasmasphere and magnetosphere, especially near the plasmapause. During geomagnetically active times multiple plasmapauses were often observed. The location of the plasmapause and the density profiles within the plasmasphere determined by these ISEE-1 and CRRES measurements as a function of local time and geomagnetic activity will be presented and compared with results acquired from other satellite and ground measurements.
Contact Information