A Heliospheric Imager for Deep Space: Lessons Learned from Helios, SMEI, and STEREO

Abstract

The zodiacal-light photometers on the twin Helios spacecraft, the Solar Mass Ejection Imager (SMEI) on the Coriolis spacecraft, and the Heliospheric Imagers (HIs) on the Solar-TErrestrial RElations Observatory (STEREO) twin spacecraft all point the way to optimizing future remote-sensing Thomson-scattering observations from deep space. Such data could be provided by wide-angle viewing instruments on Solar Orbiter, Solar Probe, or other deep-space probes. Here, we present instrument specifications required for a successful heliospheric imager, and the measurements and data-processing steps that make the best use of this remote-sensing system. When this type of instrument is properly designed and calibrated, its data are capable of determining zodiacal-dust properties, and of threedimensional reconstructions of heliospheric electron density over large volumes of the inner heliosphere. Such systems can measure fundamental properties of the inner heliospheric plasma, provide context for the in-situ monitors on board spacecraft, and enable physicsbased analyses of this important segment of the Sun-spacecraft connection.Remote Sensing of the Inner Heliosphere

The Solar Mass Ejection Imager and Its Heliospheric Imaging Legacy

“…As mentioned here and in the Introduction, and discussed at length in Jackson et al (2010a), the Helios heritage had already provided important lessons that were employed in the SMEI design and were critical for delivering its success.…”

“…Several reports and presentations have already been published on lessons learned from SMEI, including , Jackson et al (2007cJackson et al ( , 2010a, and . These articles highlight significant factors to consider, including the above, when designing a next generation of heliospheric imagers, wherever they may be deployed.…”

“…6.1 and 6.2) to develop a better quality imager and enable more accurate calibration and scientific data extraction. To this end, Buffington et al (1998), Jackson et al (2010aJackson et al ( , 2011a have proposed the All-Sky Imager (ASI). This instrument views almost an entire hemisphere of directions relative to the Sun, from 2…”

Using Coordinated Observations in Polarized White Light and Faraday Rotation to Probe the Spatial Position and Magnetic Field of an Interplanetary Sheath

“…Such a configuration was discussed qualitatively by Jackson et al (2010) and is analyzed quantitatively in Section 3 of this paper. Observations from STEREO/HI suggest that a traveling sheath can be approximated as an expanding bubble (e.g., Howard & Tappin 2009;Lugaz et al 2010;Davies et al 2012;Möstl & Davies 2013).…”

The utility of polarized heliospheric imaging for space weather monitoring

“…By collecting multiple images per orbit of each portion of the sky, one can identify and remove samples that are contaminated by aurora, preserving the remainder of the samples and thereby generating full field‐of‐view, aurora‐free image data products by combining the multiple images from each orbit. This was not easily possible with SMEI because of limitations of its platform: SMEI was originally designed for a spinning platform but was later adapted to the three‐axis stabilized, nadir‐pointed Coriolis spacecraft [e.g., Jackson et al , ]. Its linear detectors scanned around the sky as the spacecraft rotated, and SMEI therefore sampled each portion of the sky only once per orbit.…”