Solar Physics 225 (1), 177−207, 2005
© Springer Verlag

The Solar Mass Ejection Imager (SMEI) Mission

B.V. Jackson, A. Buffington and P.P. Hick
Center for Astrophysics and Space Science, University of California, San Diego, CA, USA

R.C. Altrock, S. Figueroa, P.E. Holladay, J.C. Johnston, S.W. Kahler,
J.B. Mozer, S. Price, R.R. Radick, R. Sagalyn and D. Sinclair,
Air Force Research Laboratory/Space Vehicles Directorate (AFRL/VS), Hanscom AFB, MA, USA

G.M. Simnett, C.J. Eyles, M.P. Cooke, and S.J. Tappin
School of Physics and Space Research, University of Birmingham, UK

T. Kuchar, D. Mizuno, D.F. Webb and P.A. Anderson
Boston University, Boston, MA, USA

S.L. Keil
National Solar Observatory, Sunspot, NM, USA

R.E. Gold
Applied Physics Laboratory, Johns Hopkins University, Laurel, MD, USA

N.R. Waltham
Space Science Department, Rutherford-Appleton Laboratory, Chilton, UK


We have launched into near-Earth orbit a Solar Mass Ejection Imager (SMEI) that is capable of measuring sunlight Thomson-scattered from heliospheric electrons from elongations to as close as 18° to greater than 90° from the Sun. SMEI is designed to observe time-varying heliospheric brightness of objects such as coronal mass ejections, corotating structures and shock waves. The instrument evolved from the heliospheric imaging capability demonstrated by the zodiacal light photometers of the Helios spacecraft. A near-Earth imager can provide up to three days warning of the arrival of a mass ejection from the Sun. In combination with other imaging instruments in deep space, or alone by making some simple assumptions about the outward flow of the solar wind, SMEI can provide a three-dimensional reconstruction of the surrounding heliospheric density structures.