NASA’s PUNCH Mission to Study the Sun’s Environment Moves Toward Launch

NASA’s PUNCH mission – short for Polarimeter to Unify the Corona and Heliosphere – passed a mission review on July 23, 2021, moving the mission into its next phase with a new target launch readiness date of October 2023.

“With PUNCH we will finally be able to see directly the connection between the star at the center of our solar system, and the solar wind that immerses our planet and gives rise to space weather here on Earth,” said Dr. Craig DeForest, PUNCH principal investigator at Southwest Research Institute, in Boulder, Colorado. “To do that, we are building four cameras to photograph the very faint rays of sunlight that are reflected off of free electrons in interplanetary space.”

coronagraph image showing solar wind streaming away from Sun
Processed data from NASA’s Solar Terrestrial Relations Observatory shows the Sun’s outer atmosphere, the corona, as it streams outward and becomes the solar wind. The upcoming PUNCH mission will study this transition and how the solar wind and transients evolve through the inner solar system. Credit: Craig DeForest, SwRI

The review, Key Decision Point C, evaluated the mission’s preliminary design and program plan to achieve launch by its target launch readiness date. With the successful review, PUNCH now moves into phase C, which includes the final design of the mission and building the instruments. The four spacecraft will then go through final assembly and testing before their launch readiness date of October 2023. This phase of the mission also marks the start of the PUNCH Outreach Program. PUNCH scientists will collaborate with five planetariums and science centers, plus other cross-cultural partners, to activate an ancient and modern Sun-watching theme that will engage historically marginalized populations.

PUNCH will consist of four suitcase-sized satellites that will study the Sun’s outer atmosphere, the corona, and how the corona accelerates to become the solar wind that fills the solar system. With images in unprecedented detail, PUNCH’s measurements will bridge a long-standing gap between remote images of the corona and solar wind and direct in situ measurements of the solar wind. PUNCH will also provide brand-new 3D information about this region, by taking advantage of the way light scatters off electrons here. PUNCH’s data will allow scientists to answer questions about how the Sun’s atmosphere becomes the solar wind that fills the solar system, as well as how structures in the solar wind are created, and how large magnetic explosions called coronal mass ejections propagate through the solar system. Such information can shed new light on how the Sun drives a vast system of space weather across the solar system, which can affect astronauts and technology on Earth and in space.

Animation of the the Sun's corona and solar wind in line drawing format
Animation (not to scale) showing the Sun’s corona and solar wind.
Credits: NASA’s Goddard Space Flight Center/Lisa Poje

“Here on Earth, we can see the Sun’s corona during a total solar eclipse. By creating an artificial eclipse, PUNCH will continuously image the upper corona, solar wind, and track coronal mass ejections, with extraordinary detail and coverage,” said Dr. Nicholeen Viall, PUNCH mission scientist at NASA’s Goddard Space Flight Center in Greenbelt, Maryland.

The four PUNCH satellites will spread out around Earth along the day-night line to create a complete view of the corona and solar wind. Three of the PUNCH satellites will carry identical Wide Field Imagers, which, together, image the corona and solar wind out to 45 degrees away from the Sun. (In skywatching terms, 90 degrees covers the part of the sky from the horizon to the point directly overhead.) The fourth PUNCH satellite carries a Narrow Field Imager, which will study regions closest to the Sun. All four cameras will be synchronized in flight, so that the mission science team can combine their images seamlessly into a single large field of view.

“PUNCH is an exciting mission that will give heliophysicists around the world a new view of the Sun’s connection to space,” said Dr. Lika Guhathakurta, PUNCH program scientist at NASA Headquarters in Washington, D.C. “PUNCH’s observations from new vantage points – in addition to our existing fleet of spacecraft – will greatly complement and enhance the scientific understanding of the Sun and its connection to Earth and space.”

PUNCH is led by Southwest Research Institute’s Boulder, Colorado, office. The mission is managed by Explorers Program Office at NASA’s Goddard Space Flight Center in Greenbelt, Maryland, which is managed by Goddard for NASA’s Science Mission Directorate in Washington, D.C. Southwest Research Institute will build the Wide Field Imagers and will build and operate PUNCH. The Naval Research Laboratory in Washington will build the Narrow Field Imagers and provide optical testing. RAL Space in the United Kingdom will provide detectors and calibration for the mission.

By Sarah Frazier
NASA’s Goddard Space Flight Center, Greenbelt, Md.