The Solar Mass Ejection Imager and Its Heliospheric Imaging Legacy

T A Howard,D F Webb,M M Bisi,S D Price,A J Penny,J M Clover,P P Hick,R R Radick,D R Mizuno,T A Kuchar,A Buffington,B V Jackson,P E Holladay,S J Tappin,S W Kahler,C J Eyles,G M Simnett,J C Johnston,Mark Cooke ,Nicholas R Waltham

doi:10.1007/s11214-013-9992-7

Abstract

The Solar Mass Ejection Imager (SMEI) was the first of a new class of heliospheric and astronomical white-light imager. A heliospheric imager operates in a fashion similar to coronagraphs, in that it observes solar photospheric white light that has been Thomson scattered by free electrons in the solar wind plasma. Compared with traditional coronagraphs, this imager differs in that it observes at much larger angles from the Sun. This in turn requires a much higher sensitivity and wider dynamic range for the measured intensity. SMEI was launched on the Coriolis spacecraft in January 2003 and was deactivated in September 2011, thus operating almost continuously for nearly nine years. Its primary objective was the observation of interplanetary transients, typically coronal mass ejections (CMEs), and tracking them continuously throughout the inner heliosphere. Towards this goal it was immediately effective, observing and tracking several CMEs in the first month of mission operations, with some 400 detections to follow. Along with this primary science objective, SMEI also contributed to many and varied scientific fields, including studies of corotating interaction regions (CIRs), the high-altitude aurora, zodiacal light, Gegenschein, comet tail disconnections and motions, and variable stars. It was also able to detect and track Earth-orbiting satellites and space debris. Along with its scientific advancements, SMEI also demonstrated a significantly improved accuracy of space weather prediction, thereby establishing the feasibility and usefulness of operational heliospheric imagers. In this paper we review the scientific and operational achievements of SMEI, discuss lessons learned, and present our view of potential next steps in future heliospheric imaging.

Highlights

The last decade witnessed the emergence of a new class of visible white-light imager for heliospheric observations
We divide this section into two parts: primary, where we report on work related to coronal mass ejections (CMEs) and related science; and additional, where we briefly review the other scientific advancements
This amounts to less than 10 % of the CMEs observed by the Large Angle Spectroscopic Coronagraph (LASCO, Brueckner et al 1995) and cataloged during the same period: compare, for example, with 9955 CMEs from CDAW and 4462 from CACTus

Summary

Introduction

The last decade witnessed the emergence of a new class of visible white-light imager for heliospheric observations. Heliospheric imagers require a much higher sensitivity and larger dynamic range than coronagraphs, enabling them to observe across much greater angular spans in the sky, and to larger distances from the Sun. Heliospheric Imagers (HIs) are carried on board the twin spacecraft of the Solar Terrestrial Relations Observatory (STEREO) mission (Eyles et al 2009), but the first such instrument was the Solar Mass Ejection Imager (SMEI). Heliospheric Imagers (HIs) are carried on board the twin spacecraft of the Solar Terrestrial Relations Observatory (STEREO) mission (Eyles et al 2009), but the first such instrument was the Solar Mass Ejection Imager (SMEI) This instrument (Eyles et al 2003; Jackson et al 2004) was launched in 2003, de-activated in 2011, and operated almost cont1i8n◦uoouustwlyadrdusrifnrgomitsth8e12. It observed almost the entire Sun (>0.35 AU in the plane of the sky)

Results

Discussion

Conclusion