NASA is preparing to launch a new mission designed to provide unprecedented insight into the solar wind—charged particles constantly streaming from the Sun that influence space weather.
The Polarimeter to Unify the Corona and Heliosphere (PUNCH) mission consists of four small satellites that will work together to observe how the Sun’s corona transitions into the solar wind and spreads throughout the solar system.
Scheduled for launch on Sunday, March 2, PUNCH will enter a sun-synchronous low polar orbit, where it will continuously monitor solar activity from space. The mission will offer a three-dimensional view of the corona as it expands into the solar wind, an effort that could transform how scientists predict space weather events.
“We expect we’ll revolutionize how space weather is forecasted,” said Craig DeForest, the mission’s principal investigator from the Southwest Research Institute.
The four satellites in the PUNCH constellation are equipped with advanced imaging technology to study different aspects of the solar wind:
- One satellite carries a narrow-field imager with a coronagraph, a device that simulates a total solar eclipse by blocking the Sun’s bright disk, making it easier to observe the outer corona.
- The other three satellites are equipped with wide-field imagers that will track the solar wind as it moves away from the Sun and spreads through space.
These instruments work by detecting polarized light—light that oscillates in specific directions. Much like polarized sunglasses reduce glare, PUNCH’s specialized filters will isolate light scattered by electrons in the solar wind.
However, this signal is extremely faint, accounting for only 0.1% of the total polarized light in space. The mission team will use sophisticated data processing techniques to extract this valuable information, which will also result in the most detailed polarimetric star map ever created, aiding astrophysicists in studying stellar properties.
PUNCH will play a crucial role in monitoring coronal mass ejections (CMEs)—large eruptions of plasma from the Sun that can travel through space and impact Earth. When a CME reaches Earth, it can cause geomagnetic storms, affecting satellites, power grids, and radio communications, while also producing vibrant auroras near the poles.
By tracking CMEs from the moment they leave the Sun, PUNCH will help scientists determine their speed, trajectory, and potential impact on Earth.
“PUNCH is the first mission able to track space weather events in three dimensions,” said DeForest.
Beyond forecasting space weather, PUNCH aims to uncover the fine structure of the solar wind, which remains a mystery. Scientists know that the transition from the corona to the solar wind is not smooth—features such as magnetic switchbacks, turbulence, and clumps of plasma suggest a more complex process.
“The amount of detail that PUNCH will capture is incredible,” said NASA scientist Nicholeen Viall. “We will see the large-scale structure of coronal mass ejections as well as smaller features that are still significant compared to the Earth.”
PUNCH will complement NASA’s Parker Solar Probe, which flies closer to the Sun than any other spacecraft. By combining Parker’s close-up data with PUNCH’s wide-field observations, scientists will gain a more complete picture of how the solar wind forms and spreads.
Additionally, PUNCH will work alongside NASA’s Interstellar Mapping and Acceleration Probe (IMAP), set to launch later this year. While PUNCH observes the birth of the solar wind near the Sun, IMAP will study how it interacts with interstellar space at the edge of the solar system.
PUNCH is scheduled to launch on March 2 aboard a SpaceX Falcon 9 rocket from Vandenberg Space Force Base in California. It will share its ride with NASA’s SPHEREx mission, which aims to study the origins of the universe and search for key ingredients of life in space.
