PUNCH, a bold new NASA mission, has successfully taken its first images of the Sun’s corona from orbit using four suitcase-sized satellites acting in unison.
These nimble spacecraft will capture how the outer solar atmosphere transforms into solar wind — a dynamic force that shapes our solar system. With pioneering imaging and water-powered thrusters, PUNCH is already pushing the limits of space technology and solar science.
PUNCH Mission Begins Solar Imaging
The Polarimeter to Unify the Corona and Heliosphere (PUNCH) mission, led by the Southwest Research Institute (SwRI), has captured its first images following its launch into Earth’s polar orbit on March 11. The mission consists of four compact, suitcase-sized satellites that work together as a single virtual instrument spanning 8,000 miles. Their goal is to image the solar corona — the Sun’s outer atmosphere — and track how it transitions into the solar wind, the continuous stream of charged particles that shapes our solar system.
“We opened the instrument doors on the Near Field Imager (NFI) and one Wide Field Imager (WFI) on April 14,” said PUNCH Principal Investigator Dr. Craig DeForest of SwRI’s Solar System Science and Exploration Division located in Boulder, Colorado. “On April 16, the other two WFIs opened their doors collected their first-light demonstration images also. All four instruments are functioning as designed. We’re excited to finish on-orbit commissioning and get these cameras working together.”
Unveiling the Invisible Solar Wind
The PUNCH satellite constellation includes one spacecraft equipped with an NFI coronagraph, built by the U.S. Naval Research Laboratory, which provides continuous images of the Sun’s corona. The other three satellites carry WFIs — heliospheric imagers developed by SwRI — designed to capture extremely faint light from the outermost corona and the solar wind itself.
Features in the tenuous solar wind, streaming out from the Sun at over a million miles per hour, are less than 0.1% as bright as the Milky Way galaxy backdrop. PUNCH raw images contain mostly stars and “zodiacal light” — a haze of dust orbiting the Sun in the inner solar system. Eliminating the starfield and the zodiacal light, while preserving the very faint solar wind signal, requires extraordinary care because the smallest artifact or miscalibration would swamp the solar wind signal.
Countdown to Full Operations
The spacecraft are in the midst of a 90-day commissioning period, operating from SwRI’s Mission Operations Center. Then, in June 2025, the science mission begins, and the Science Operations Center will begin processing the data to share with NASA and the rest of the world.
“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 said. “The three WFI ‘first-light’ images show star fields, but the ultimate goal is to remove the star field and other background light and preserve the faint glimmer of the solar wind as it travels to Earth.”
Water-Powered Propulsion Milestone
During commissioning, PUNCH also demonstrated novel, water-powered, shot-glass-sized rocket engines. To run the engine, each spacecraft electrolyzes water, building up small stores of high-pressure hydrogen and oxygen that it then burns as fuel. Each cycle delivers a “kick” of about one inch per second (2 cm/sec), just enough to correct for small orbital shifts and keep the constellation stable.
“PUNCH is the first space mission to rely on this type of engine, which carries safe, inert, non-toxic propellant,” DeForest said. “That safety and stability are worth it even though the thrusters are more complex than conventional hydrazine rockets.”
Coordinated Orbital Ballet
Each satellite needs to fire its thruster hundreds of times, reliably and repeatably, over the course of the mission. On April 2, as part of its commissioning, the WFI-2 spacecraft demonstrated its first three charge-and-fire cycles, modifying its orbital velocity relative to the other PUNCH spacecraft as they drift apart to reach their final positions — a third of the way around the world from one another.
Inside each instrument, a space rated scientific-grade camera developed by RAL Space will collect three raw images, through three different polarizing filters, every four minutes. This new perspective 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 coronagraphs that only measure the corona itself and also cannot measure motion in three dimensions.
The PUNCH (Polarimeter to Unify the Corona and Heliosphere) mission is a NASA-funded project led by the Southwest Research Institute. Its goal is to study how the Sun’s outer atmosphere—the corona—transitions into the solar wind, the stream of charged particles that flows through the solar system and influences space weather.
The mission uses a constellation of four small satellites, each about the size of a suitcase, working together as a single instrument in orbit. One satellite carries a coronagraph to image the bright inner corona, while the other three carry wide-field imagers designed to capture the faint, extended structures of the outer corona and solar wind. By combining data from all four spacecraft, PUNCH will create a continuous view of the solar atmosphere as it expands into space—helping scientists better understand the dynamics of the Sun and its impact on Earth.
Never miss a breakthrough: Join the SciTechDaily newsletter.
Follow us on Google and Google News.