The High Inclination Solar Mission

Abstract

The High Inclination Solar Mission (HISM) is a concept for an out-of-the-ecliptic mission for observing the Sun and the heliosphere. The mission profile is largely based on the Solar Polar Imager concept [Liewer et al., 2008]; initially taking ∼2.6 yrs to spiral in to a 0.48 AU ecliptic orbit, then increasing the orbital inclination at a rate of ∼ 10 degrees per year, ultimately reaching a heliographic inclination of >75 degrees. The orbital profile is achieved using solar sails derived from the technology currently being developed for the Solar Cruiser mission, currently under development.HISM remote sensing instruments comprise an imaging spectropolarimeter (Doppler imager / magnetograph) and a visible light coronagraph. The in-situ instruments include a Faraday cup, an ion composition spectrometer, and magnetometers. Plasma wave measurements are made with electrical antennas and high speed magnetometers.The 7, 000 m 2 sail used in the mission assessment is a direct extension of the 4quadrant 1, 666 m 2 Solar Cruiser design and employs the same type of high strength composite boom, deployment mechanism, and membrane technology. The sail system modelled is spun ( 1 rpm) to assure required boom characteristics with margin. The spacecraft bus features a fine-pointing 3-axis stabilized instrument platform that allows full science observations as soon as the spacecraft reaches a solar distance of 0.48 AU.

Improving Solar Observing Capabilities with Diffractive Solar Sailing

“…It is no wonder, then, that the measurement of the solar polar magnetic field has featured prominently in past Decadal Surveys, along with the Solar Polar Imager (SPI) mission concept to measure it (Liewer et al 2009). SPI, Polaris (Appourchaux et al 2009) and, more recently HISM (Kobayashi et al 2020) have employed refractive solar sails as the propulsion of choice because it is the only known approach to achieving high inclinations (> 60º outside the ecliptic) without a Jupiter gravity assist (and the incurred penalties in cruise phase, design for Jupiter environment and multi-year gaps between polar passes). In recent years, it is been recognized that a constellation, rather than a single spacecraft, is needed to observe the magnetic field and solar atmosphere in its entirety (so-called, 4π coverage; see Vourlidas et al 2018, Raouafi et al 2022.…”