Considerations of a Solar Mass Ejection Imager in a low-earth orbit

Abstract

We are designing an imager capable of observing the Thomson scattering signal from transient, diffuse features in the heliosphere[1]. The imager is expected to trace these features, which include coronal mass ejections, co-rotating structures and shock waves, to elongations greater than 90° from the Sun from a spacecraft in an ≈800 km Earth orbit. The predecessor of this instrument was the zodiacal-light photometer experiment on the HELIOS spacecraft which demonstrated the capability of remotely imaging transient heliospheric structures [2]. The HELIOS photometers have shown it possible to image mass ejections, co-rotating structures and the density enhancements behind shock waves. The second-generation imager we are designing, would have far higher spatial resolution enabling us to make a more complete description of these features from the Sun to 1 AU. In addition, an imager at Earth could allow up to three days warning of the arrival of a solar mass ejection.