The Compact Heliospheric Imager (CHI): An R2O Instrument Concept for an L5 Space Weather Mission
Abstract
The payload complements specified for most L5 Lagrange point space weather mission concepts include a white-light coronagraph as the primary means to detect the eruption of coronal mass ejections (CMEs) and to establish their initial trajectory into interplanetary space. The design goal outer field of view for an L5 coronagraph is typically about 25 RSun. Once an Earth-directed CME leaves the L5 coronagraph's outer field of view, it loses track of the event and no information about its trajectory or speed is available to operational heliospheric disturbance propagation codes. Forecasters would be blind until the CME reaches the L1 Lagrange point along the Sun-Earth line, where the in-situ measurements would provide only 30-45 minutes of actionable lead time prior to the CME impact at Earth. Adding a heliospheric imager to the instrument suite of an L5 space weather mission will enhance its ability to continuously track CMEs as they leave the L5 coronagraph field of view, improving CME trajectory determination, CME arrival time estimation, and ultimately the accuracy of geomagnetic storm forecasts. The Compact Heliospheric Imager (CHI) is a dual-telescope instrument concept with 30° fields of view that is an ideal candidate for this role on an L5 space weather mission. CHI will image interplanetary space in white light (500-700 nm) between 4.5°-64.5° elongation from L5. This combined field of view encompasses the entire Sun-Earth line with Earth just inside the outer field of view cut off. CHI's enclosed design allows it to be placed close to other spacecraft components or instruments without those components interfering with CHI's imaging performance. This provides a great deal of flexibility in placement of CHI on a spacecraft since its only requirement is to have an unobstructed field of regard (FOR) in the Sun-facing hemisphere. CHI's compact design and low power requirements make it an ideal instrument candidate for an L5 space weather mission. The CHI concept development is supported by the ONR/NRL Bids and Proposals (B&P) Program.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2019
- Bibcode:
- 2019AGUFMSH43F3351C
- Keywords:
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- 7536 Solar activity cycle;
- SOLAR PHYSICS;
- ASTROPHYSICS;
- AND ASTRONOMY;
- 7594 Instruments and techniques;
- SOLAR PHYSICS;
- ASTROPHYSICS;
- AND ASTRONOMY;
- 7924 Forecasting;
- SPACE WEATHER;
- 7974 Solar effects;
- SPACE WEATHER