Geophysical Monograph 54, 291−297, 1989.
© American Geophysical Union

Design considerations for a "Solar Mass Ejection Imager" on a rotating spacecraft

B.V. Jackson, H.S. Hudson and J.D. Nichols
University of California, San Diego, La Jolla, CA

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


We describe an instrument capable of imaging the time-varying features of the entire outer corona (from near the Sun to beyond 90° elongation) via the Thomson-scattered diffuse solar light. This "all sky"imager works on a spin-stabilized spacecraft, preferably in deep space. The design for such an imager, which can for example study solar mass ejections at great distances from the Sun, must deal wih spurious signals from stray light, zodiacal light, and stars to surface brightness levels below 1 S10 unit. The design discussed here envisions a set of three slit apertures, feeding one-dimensional detectors through a lens system; the spacecraft rotation allows a complete sky survey during each spin of the spacecraft. Data clocked into a computer memory complete the "image" of the whole sky. We have analyzed a "median filter" approach to reducing the effects of starlight, in real time, on the statistics of the residual diffuse background. The analysis also included simulations of spacecraft nutation, spin-phase timing error, and image quality in the necessary wide-field optics.