Calvert, W., R. F. Benson, S. F. Fung, J. L. Green, M. F. Smith, D. L.
Carpenter, D. L. Gallagher, D. M. Haines, B. W. Reinisch, P. H. Reiff,
and W. W. L. Taylor, Radio sounding in the magnetosphere, presented at
the URSI General Assembly, Lille, France, Aug. 28-Sept. 5, 1996.

Radio Sounding in the Magnetosphere

W. Calvert (Department of Physics and Astronomy, The University of
Iowa, Iowa City, IA 52242, USA; Phone:  (319) 335-0564; Fax:  (319)
335-1753; 
e-mail:  wynne@calvert.physics.uiowa.edu)
R. F. Benson, S. F. Fung, J. L. Green and M. F. Smith (NASA/Goddard
Space Flight Center, Greenbelt, MD 20771, USA)
D. L. Carpenter (Stanford University, Stanford, CA 94305, USA)
D. L. Gallagher (NASA/Marshall Space Flight Center, Huntsville, AL
35812, USA)
D. M. Haines and B. W. Reinisch (University of Massachusetts, Lowell,
Lowell, MA 01854, USA)
P. H. Reiff (Rice University, Houston, TX 77251-1892, USA)
W. W. L. Taylor (Nichols Research Corporation, Arlington, VA 22209,
USA)


In a recent publication [1], the feasibility of radio sounding in the
magnetosphere was considered.  It was shown that a radio sounder
outside the plasmasphere could provide nearly continuous remote
density measurements of the magnetopause and plasmasphere, as well as
other important density features elsewhere in this region.  Using
digital integration and tuned reception at frequencies from a few
kilohertz to a few megahertz with 400-m to 500-m tip-to-tip dipole
antennas and 10 W transmitter power, such a sounder would be capable
of 10% density resolution and 500 to 1300 km spatial resolution in
only a few minutes at distances of up to 4 RE.  It was claimed that by
providing such detailed observations of its principal density
structures, such a sounder would revolutionize magnetospheric
research.  Some of the science objectives of magnetospheric radio
sounding have been discussed in earlier publications [2,3,4.].  Here,
the results of the feasibility study [1] will be reviewed, recent
questions concerning the technique will be addressed and possible
flight opportunities will be discussed.


References
[1] W. Calvert et al., Radio Sci., 30, pp 1577-1595, 1995
[2] J. L. Green, and S. F. Fung, Adv. Space Res., 14, pp
(6)217-(6)221, 1994
[3] P H. Reiff et al., Eos Trans. AGU, 75, pp 129-134, 1994
[4[ P. H. Reiff et al., in Substorms 2, Proceedings of the Second
International Conference on
  Substorms, J. R. Kan, J. D. Craven and S.-I. Akasofu (eds),
University of Alaska Press,
  Fairbanks, Alaska, pp 281-287, 1994