Polarimeter to UNify the Corona and Heliosphere: Science Summary and Mission Status

The Polarimeter to UNify the Corona and Heliosphere (PUNCH) is a constellation mission being built within NASA’s Small Explorer program. During its two year nominal mission, PUNCH will use a constellation of four spacecraft as a single visible-light “virtual coronagraph” with a 90° outer field of view and a 1.25° inner field of view, to continuously produce global, photometric, 3D images of the outer reaches of the solar corona and the solar wind itself. PUNCH uses polarization properties of Thomson scattering to extract 3D information along its single line of sight from near Earth.

The PUNCH science objectives are to understand both (1) how coronal structures become the ambient solar wind, and (2) the dynamic evolution of transient structures within the solar wind. Subtopics include mapping the evolving flow of the solar wind, identifying microstructures and turbulence in the young solar wind, locating the Alfvén surface and other natural boundaries of the corona-heliosphere system, tracking CMEs and their evolution in 3D, measuring the formation of solar wind co-rotating interaction regions, and determining the large-scale dynamics of interplanetary shocks. These are addressed through deep-field 3D imaging, using the polarization properties of Thomson-scattered light.

PUNCH is finishing up its Phase B (preliminary design), with KDP-C expected in 2021 July and a Launch Readiness Date in late 2023.

This poster summarizes the science objectives, novel approach, and current status of the mission.