August 4, 2026 — A Southwest Research Institute-led paper documents how NASA’s Polarimeter to Unify the Corona and Heliosphere mission could greatly improve the ability to forecast the arrival of coronal mass ejections (CMEs). These vast clouds of magnetized plasma can disrupt satellites, power grids and communications when they strike Earth.
Since PUNCH’s four small suitcase-sized spacecraft launched on March 11, 2025, they have synced up to act as a single virtual instrument 8,000 miles across. In addition to imaging the Sun’s outer atmosphere as it transitions into the solar wind, PUNCH has tracked enormous coronal mass ejections flinging plasma across the sky and washing over the Earth.
“Forecasting exactly when a CME will arrive is difficult because many conventional solar cameras often lose sight of the cloud long before it reaches us,” said SwRI’s Dr. Craig DeForest, lead author of the paper and PUNCH’s principal investigator. “The SwRI-developed and -led Wide Field Imagers aboard three of the four PUNCH spacecraft are collecting high-resolution images of entire CMEs over most of their trajectory, in greater detail than previously possible.”
Fast CMEs are one of the main sources of strong space weather events at Earth. Developing techniques to forecast the arrival time and directness of CME impacts is driving a significant portion of space weather physics. Because PUNCH images a wide swath of the sky, in late May 2026 the mission followed its first fast Earth-directed CME nine-tenths of the way from the Sun to Earth.
PUNCH scientists used a very simple geometric model of the CME, an “ice cream cone model.” The tip of the cone represents where a CME originates, and the “ice cream scoop” at the top represents the CME itself as it expands and moves through the solar system.
“By tracing by hand the glowing front of the cloud in images collected in May, we created a very simple geometric model to produce arrival-time forecasts. These ‘retro-forecasts’ predicted the arrival time, within a 30-minute window, eight hours before it hit,” DeForest said. “This is about ten times better than current CME forecasting can achieve, using much more sophisticated models but extrapolating from coronagraph images alone.”
The proof-of-concept result shows that continuous wide-field imaging from near Earth can substantially sharpen space weather forecasts.
“Our team used an incredibly simple model, based on just three geometric parameters, to make these retro-forecasts,” DeForest said. “PUNCH’s high-fidelity data provided clear convergence that improved and stabilized as new data arrived.”
PUNCH views the corona and solar wind as a single system, providing a big-picture perspective essential to helping scientists better understand our neighborhood in space — and the weather that fills it.
“PUNCH is a scientific mission to understand the Earth’s environment in space,” DeForest said. “These findings demonstrate that the same kind of data could be used to greatly improve space weather forecasting in the years to come.”
SwRI’s Solar System Science and Exploration Division leads the PUNCH mission and operates the four spacecraft from its facilities in Boulder, Colorado. The Boulder division is part of SwRI’s Space Sector, based in San Antonio. The mission is managed by the Explorers Program Office at NASA Goddard Space Flight Center in Greenbelt, Maryland, for the Science Mission Directorate at NASA Headquarters in Washington, D.C.
Watch an interview with PUNCH Principal Investigator Craig DeForest: https://youtu.be/Qqtakkfo-mg
For more information, visit Heliophysics or contact Deb Schmid, +1 210 522 2254, Communications Department, Southwest Research Institute, 6220 Culebra Road, San Antonio, TX 78238-5166.