NASA’s PUNCH mission, designed to unravel the mysteries of the solar wind, has captured its first-light images, marking a key milestone in its 90-day commissioning phase. Scientists say the instruments are working as expected, and the mission is on track to deliver new insights into how the Sun’s corona transitions into the heliosphere.
Four Satellites, One Instrument
Rather than a single probe, PUNCH (short for Polarimeter to Unify the Corona and Heliosphere) is a constellation of four small satellites strategically deployed in Earth’s orbit. Working in tandem, they behave like a single wide-field instrument with a unique ability: spotting and tracking faint features in the solar wind.
“All four instruments are functioning as designed. We’re excited to finish on-orbit commissioning and get these cameras working together,” said Craig DeForest, lead scientist of the mission at the Southwest Research Institute (SwRI) in Boulder, Colorado.
Zodiacal Light and Star Fields
The first-light images, taken on April 14 and 16, reveal star-filled skies shrouded in a warm amber haze — a glow known as the zodiacal light, created when dust particles orbiting the Sun reflect sunlight. Some constellations, including Taurus and Cetus, can be seen, but they are not the ultimate target.
These stars and the zodiacal light will be digitally removed from the images. The mission aims to isolate the faint glow of the solar wind as it emerges from the Sun’s outer atmosphere, or corona.
“Throughout the commissioning phase, the PUNCH team is calibrating the NFI data to remove 99% of the light to show materials streaming out from the Sun’s outer atmosphere in stunning detail,” DeForest explained.
Building A 3D Map Of The Solar Wind
PUNCH’s instruments include three wide-field imagers (WFIs) and one near-field imager (NFI). Together, they will create a 90-degree panoramic view of the solar corona and heliosphere. The mission will take advantage of a subtle optical phenomenon: light polarization.
“A polarimeter is a camera that can measure polarized light like you might see through a pair of polarized sunglasses, and we use that to measure what we’re imaging in three dimensions,”said DeForest. “That scattering process polarizes the light, and the degree of polarization tells us where the object was in three dimensions.”
This technique could allow researchers to map the solar wind in 3D for the first time — a potential breakthrough for space weather forecasting and heliophysics research.
Testing Water-powered Propulsion
Beyond the scientific payload, the mission is also a testbed for innovative spacecraft propulsion. During commissioning, the PUNCH team demonstrated the performance of new “water-powered, shot-glass-sized” rocket engines.
These engines use electrolysis to split water into hydrogen and oxygen, which are then combusted to produce thrust. The system offers a safe and non-toxic alternative to traditional propulsion methods.
According to DeForest, the “safety and stability” of this system is a major benefit, especially since each satellite in the constellation must maneuver hundreds of times to maintain proper formation.
First Science Data Coming This Summer
PUNCH launched on March 11, sharing a SpaceX Falcon 9 rocket with NASA’s SPHEREx mission, which aims to map the sky in near-infrared wavelengths. After completing its commissioning period, PUNCH is expected to begin scientific operations by June, with data release and analysis following shortly after.
The mission’s ultimate goal is to answer a long-standing puzzle in solar physics: how the hot, structured corona becomes the turbulent solar wind. time, we may have the right tools to see it clearly.
