T. E. Moore, ^* C. R. Chappell, M. O. Chandler, P. D. Craven, B. L. Giles, C. J. Pollock, J. L. Burch, D. T. Young, J. H. Waite Jr., J. E. Nordholt, M. F. Thomsen, D. J. McComas, J. J. Berthelier, W. S. Williamson, R. Robson, F. S. Mozer

Plasma outflows, escaping from Earth through the high-altitude polar caps into the tail of the magnetosphere, have been observed with a xenon plasma source instrument to reduce the floating potential of the POLAR spacecraft. The largest component of H⁺ flow, along the local magnetic field (30 to 60 kilometers per second), is faster than predicted by theory. The flows contain more O⁺ than predicted by theories of thermal polar wind but also have elevated ion temperatures. These plasma outflows contribute to the plasmas energized in the elongated nightside tail of the magnetosphere, creating auroras, substorms, and storms. They also constitute an appreciable loss of terrestrial water dissociation products into space.

T. E. Moore, C. R. Chappell, M. O. Chandler, P. D. Craven, B. L. Giles, NASA Marshall Space Flight Center, Huntsville, AL, USA.
C. J. Pollock, J. L. Burch, D. T. Young, J. H. Waite Jr., Southwest Research Institute, San Antonio, TX, USA.
J. E. Nordholt, M. F. Thomsen, D. J. McComas, Los Alamos National Laboratories, Los Alamos, NM, USA.
J. J. Berthelier, Centre d'Etudes Terrestraire et Planetaire, St. Maur-des-Fossés, France.
W. S. Williamson and R. Robson, Hughes Research Laboratories, Malibu, CA, USA.
F. S. Mozer, University of California, Berkeley, CA, USA.
^*   Present address: NASA Goddard Space Flight Center, Greenbelt, MD 20771, USA.

   Present address: Vanderbilt University, Nashville, TN 37212, USA.