Dust in the wind: The dust geometric cross section at 1 AU
based on neutral solar wind observations

Michael R. Collier (1), Thomas E. Moore (1), K. Ogilvie (1), D.J. Chornay (1), 
J. Keller (1), S. Fuselier (2), J. Quinn (3), P. Wurz (4), M. WŸest (5), 
and K.C. Hsieh (6)

(1) NASA/Goddard Space Flight Center, Code 692, Greenbelt, Maryland 20771
(2) Lockheed Martin Advanced Technology Center, Palo Alto, CA 94304
(3) University of New Hampshire, Durham 03824
(4) University of Bern, CH-301, Switzerland
(5) Southwest Research Institute, 6220 Culebra Road, San Antonio, TX 78228-0510
(6) Department of Physics, University of Arizona, Tucson, AZ 85721

We report observations of the neutral component of the solar wind from the Low
Energy Neutral Atom (LENA) imager on the NASA IMAGE spacecraft from year 2001. 
There is a pronounced annual modulation of the neutral solar wind, and the flux 
outside of the upstream region is used to place an upper limit on the dust 
geometric cross section in the sunward direction at 1 AU of 
Gamma (1 AU) < 6 x 10^-19 cm^-1 . This value agrees with inferences made from 
the zodiacal light.

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Solar Wind 10, Proceedings of the Tenth International Solar Wind Conference, 
M. Velli, R. Bruno, and F. Malara, eds., AIP Conference Proceedings Volume 679,
American Institute of Physics, Melville, New York, pp. 790-793, 2003