The Solar Mass Ejection Imager (SMEI), (Jackson et al., 19891; 19972; Keil et al., 19963) launched  6 January 2003 into an Earth-terminator, Sun-synchronous, 840 km polar orbit, provides an effective means for tracking interplanetary disturbances to Earth, across the observational gap left by near-Sun coronagraph observations. SMEI employs never-before attempted baffle and imaging capability (Buffington et al., 20034) that allows it to view the whole sky around Earth photometrically to a high accuracy. It provides Thomson-scattering data that are related directly to the solar wind density flowing outward from the Sun.

 Click for Large First Light Image


The tomographic techniques incorporating a purely kinematic model that are now used with the ground-based interplanetary scintillation (IPS) data provided by Solar Terrestrial Environment Laboratory (STELab), Nagoya University, Japan (, were re-developed for use with SMEI (Jackson et al., 20035). They work as well, or better (in many cases) with Thomson scattering remote-sensing observations than they do currently with IPS. SMEI data allows the reconstruction of CMEs and other heliospheric structures such as corotating interaction regions (CIRs) as they move outward from the Sun, with a 102-minute cadence at spatial resolutions of 0.05 AU in height, and with angular dimensions of 1o x 1o in latitude and longitude.

SMEI provides ~10 times higher tomographic resolution in all four dimensions than is possible with current STELab IPS data. To do this, a SMEI 0.1% differential photometric precision is needed, and often obtained to be used for the 3D tomographic reconstructions in combination with the IPS velocity data from STELab. We at CASS/UCSD plan to continually update and refine this capability as data is processed and re-processed with newly-developed routines.

Coriolis Mission Patch

  SMEI Field of View

SMEI is a joint project of UCSD, Boston College, the University of Birmingham (UK), and the Air Force Research Laboratory. UCSD has been responsible for the overall design and preliminary development of the instrument baffle, CCD selection and testing, and the optics construction and calibration. Space imaging data are already being analyzed by SMEI team members.


  1. Jackson, B.V., Hudson, H.S., Nichols, J.D. and Gold, R.E., "Design Considerations for a 'Solar Mass Ejection Imager' on a Rotating Spacecraft", in: J.H. Waite, Jr., J.L. Burch and R.L. Moore (eds.), Solar System Plasma Physics, Geophysical Monograph 54, 291, 1989
  2. Jackson, B.V., Buffington, A., Hick, P., Kahler, S.W., Keil, S.L, Simnett, G. and Webb, D.F., "The Solar Mass Ejection Imager", Physics and Chemistry of the Earth 22 (5), 441−444, 1997
  3. Keil, S.L, Altrock, R.C., Kahler, S.W., Jackson, B.V., Buffington, A., Hick, P., Simnett, G., Eyles, C., Webb, D.F. and Anderson, P., "The Solar Mass Ejection Imager (SMEI): Development and Use in Space Weather Forecasting", in: K.S. Balasubramaniam, S.L. Keil and R.N. Smartt (eds.), Solar Drivers of Interplanetary and Terrestrial Disturbances, ASP Conf. Series 95, 158−165, 1996
  4. Buffington, A., Jackson, B.V. and Hick, P.P., "Calculations for, and laboratory measurements of a multistage labyrinthine baffle for SMEI", Proc. SPIE 4853, 490−503, 2003
  5. Jackson, B.V., Hick, P.P. and Buffington, A., "Time-dependent tomography of heliospheric features using the three-dimensional reconstruction techniques developed for the Solar Mass Ejection Imager (SMEI)", Proc. SPIE 4853, 23−30, 2003