SwRI-led PUNCH constellation launches

(Press-News.org) SAN ANTONIO — March 12, 2025 — Four small suitcase-sized spacecraft, designed and built by Southwest Research Institute headquartered in San Antonio, launched from Vandenberg Space Force Base in California on March 11. NASA’s Polarimeter to Unify the Corona and Heliosphere, or PUNCH, constellation has spread out in a low-Earth orbit along the day-night line, providing a clear view in all directions for its two-year primary mission.

“The PUNCH spacecraft are now drifting into perfect position to study the solar corona, the Sun’s outer atmosphere, as it transitions into the solar wind that fills our solar system,” said PUNCH Principal Investigator Dr. Craig DeForest of SwRI’s Solar System Science and Exploration Division located in Boulder, Colo. “To get the data we need, we had to create an instrument as large as the Earth. Because that wasn’t possible, we used four small spacecraft, synchronized and spread around the entire planet, to create a virtual instrument 8,000 miles across.  That lets us look up to 45° from the Sun in all directions, all the time.”

One satellite carries a coronagraph, the Narrow Field Imager developed by the U.S. Naval Research Laboratory, that images the Sun’s corona continuously. The other three carry SwRI-developed Wide Field Imagers, designed to view the very faint outermost portion of the solar corona and the solar wind itself. PUNCH will also track space weather events, such as coronal mass ejections traveling across the solar system, in three dimensions for the first time.

“PUNCH will make the invisible visible,” DeForest said. “Deep baffles in our wide-field imagers reduce direct sunlight by over 16 orders of magnitude or a factor of 10 million billion — the ratio between the mass of a human and the mass of a cold virus. Then state-of-the-art processing on the ground removes the background starfield, over 99% of the light in each image, to reveal the extremely faint glimmer of the solar wind.”

The spacecraft have started a 90 day-commissioning period from the Mission Operations Center, located at SwRI’s Boulder, Colo., offices. In June 2025, the science mission begins, and the Science Operations Center will begin sharing data with the rest of the world, via NASA’s Solar Data Analysis Center.

Each spacecraft includes a camera, developed by RAL Space in the United Kingdom, to collect three raw images, through three different polarizing filters, every four minutes. In addition, each spacecraft will produce a clear unpolarized image every eight minutes, for calibration. These images will allow scientists to discern the exact trajectory and speed of coronal mass ejections as they move through the inner solar system, improving on current instruments that only measure the corona itself and also do not routinely exploit the polarization of light.

“While PUNCH is a research mission, we will be able to track space storms, or coronal mass ejections, in three dimensions as they approach the Earth — this is critical to forecasting space weather and how it might affect us as a space-faring society,” DeForest said. “We hope PUNCH will help revolutionize space weather forecasting in the same way that geosynchronous satellites revolutionized weather forecasting on Earth.”

PUNCH shared a ride to space with NASA’s Spectro-Photometer for the History of the Universe, Epoch of Reionization and Ices Explorer (SPHEREx) observatory. NASA’s Small Explorers (SMEX) program provides frequent flight opportunities for world-class scientific investigations from space using innovative, efficient approaches within the heliophysics and astrophysics science areas. In addition to leading the PUNCH science mission, SwRI will operate the four spacecraft. The PUNCH team includes the U.S. Naval Research Laboratory, which built the Narrow Field Imager, and RAL Space in Oxfordshire, United Kingdom, which provided detector systems for the four visible-light cameras.

To view a video about the mission, see: https://youtu.be/3BL18jyKeOI

For more information, visit https://www.swri.org/markets/earth-space/space-research-technology/space-science/heliophysics.

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