<title>Report on new mission concept study: Stereo X-Ray Corona Imager mission</title>

Abstract

Studies of the three-dimensional structure and dynamics of the solar corona have been severely limited by the constraint of single viewpoint observations. The Stereo X-Ray Coronal Imager (SXCI) mission will send a single instrument, an X-ray telescope, into deep space expressly to record stereoscopic images of the solar corona. The SXCI spacecraft will be inserted into a ~1 AU heliocentric orbit leading Earth by ~25° at the end of nine months. The SXCI X-ray telescope forms one element of a stereo pair, the second element being an identical X-ray telescope in Earth orbit placed there as part of the NOAA GOES program. X-ray emission is a powerful diagnostic of the corona and its magnetic fields, and three dimensional information on the coronal magnetic structure would be obtained by combining the data from the two X-ray telescopes. This information can be used to address the major solar physics questions of (1) what causes explosive coronal events such as coronal mass ejections (CMEs), eruptive flares and prominence eruptions and (2) what causes the transient heating of coronal loops. Stereoscopic views of the optically thin corona will resolve some ambiguities inherent in single line-of-sight observations. Triangulation gives 3D solar coordinates of features which can be seen in the simultaneous images from both telescopes. As part of this study, tools were developed for determining the 3D geometry of coronal features using triangulation. Advanced technologies for visualization and analysis of stereo images were tested. Results of mission and spacecraft studies are also reported.

The STEREO Mission: An Introduction

“…Other multi-spacecraft missions to observe the Sun were proposed in Russia (Grigoryev 1993;Grigoryev et al 1996;Chebotarev et al 1997), in Europe (Schmidt et al 1993), Canada (Timothy et al 1996) and the United States (Liewer et al 1998). Workshops provided the opportunity for the Heliophysics community to provide input into the ongoing studies (Bothmer and Foing 1996).…”

Solar Stereoscopy and Tomography

“…The data rate is highest at the beginning of the mission, but drops Living Reviews in Solar Physics http://www.livingreviews.org/lrsp-2011-5 continuously due to the lower telemetry rate later in the mission. The STEREO mission concept is described in Grigoryev (1993), Schmidt and Bothmer (1996), Socker et al (1996), Davila et al (1996), Davila (1998), Socker (1998), Rust (1998), Liewer et al (1998), Bothmer et al (1998), Socker et al (2000), Mueller et al (2003), Kaiser (2005), Kaiser et al (2008), and Driesman et al (2008).…”

Theoretical modeling for the stereo mission

“…Some 3D modeling has been accomplished before, of course, e.g., by means of solar-rotation tomography, combined imaging and Doppler-spectroscopy, or multiple in-situ spacecraft observations of the solar wind (such as with CLUSTER), but STEREO is the first mission dedicated to study the 3D evolution of CMEs and the solar wind from stereoscopic vantage points. Realistic models of the 3D structure and dynamics of solar/heliospheric plasma and particles are needed to fully exploit the science return of the data, for our exploration of the unknown physical processes whose outcome we are observing, as envisioned in a number of anticipatory pre-launch papers (Grigoryev, 1993;Pizzo et al, 1994;Davila et al, 1996;Schmidt and Bothmer, 1996;Socker et al, 1996Rust et al, 1997;Socker, 1998;Liewer et al, 1998;Davila and St. Cyr 2002;Mueller et al, 2003). Table 1 gives an overview of what the four instrument suites of the two STEREO spacecraft will yield: SECCHI/EUVI will image the solar corona, eruptive filaments, flares, and coronal mass ejections (CMEs) in the lower corona at EUV wavelengths.…”