CAPE CANAVERAL — At 7:30 a.m. on Wednesday, Sept. 24, a Falcon 9 rocket lifted off from Kennedy Space Center in Florida carrying NASA’s IMAP, a Princeton-led mission to understand the Sun’s impact on its space environment, from the surface of the Sun to Earth to the farthest reaches of the solar system. 

IMAP mission lead David McComas (right) and SWAPI instrument lead Jamie Rankin stand on the NASA balcony from which they watched the sunrise launch, just moments before.

Photo by Molly Seltzer, Office of Communications

David McComas, an astrophysics professor at Princeton University, leads the IMAP mission, the Interstellar Mapping and Acceleration Probe, which involved a team of institutions and major suppliers that spans 82 U.S. partners in 35 states, plus the United Kingdom, Poland, Switzerland, Germany and Japan.

The IMAP spacecraft carries 10 instruments that will expand scientists’ understanding of the heliosphere (named for the Greek sun god “Helios” and “sphere” or zone of influence), including monitoring the massive solar storms — known as coronal mass ejections — that can wreak havoc with Earth’s electromagnetic systems.

“Wow! Awesome! Incredible launch!” said McComas, minutes after liftoff. “The whole IMAP team is excited to be going out to L1 [the destination in space] and to be discovering the secrets of the universe.”

Jamie Rankin, a research scholar and lecturer in astrophysical sciences at Princeton, is the instrument lead for SWAPI (Solar Wind and Pickup Ion), one of the 10 instruments carried by IMAP. 

“I’m so excited!” Rankin said after the launch. “I was watching it in awe. I'm so relieved that it's off Earth, up in space where it belongs.” 

Nathan Schwadron, one of two deputy principal investigators for IMAP and the instrument lead for another of the mission’s instruments, IMAP-Lo, is a visiting research collaborator at Princeton University and a Presidential Chair at the University of New Hampshire.

“It was thrilling,” Schwadron said of the dawn launch. “It’s the culmination of an incredible amount of work.” 

Along with IMAP, two other missions shared the launch as “ride-alongs” on the same Falcon 9: NASA’s Carruthers Geocorona Observatory and NOAA’s SWFO-L1 (Space Weather Follow On-Lagrange 1).

Photo by Benjamin Fry/BAE Systems

“Cosmic carpool”

Two other missions shared the launch as “ride-alongs” on the same Falcon 9: NASA’s Carruthers Geocorona Observatory and NOAA’s SWFO-L1 (Space Weather Follow On-Lagrange 1). Together, these missions will help safeguard technology on the Earth’s surface, satellites in orbit, and space explorers from harsh space weather.

In the coming months, the three spacecraft will fly to L1, a stable location about a million miles Sun-ward of the Earth. From there, IMAP will investigate three things: the solar wind, a continuous stream of particles emitted by the Sun, all the way from its origins to the farthest reaches of our solar system; the mysterious acceleration of those particles; and the outermost boundary of the heliosphere, the cosmic shield that protects our solar system from harmful cosmic radiation.

McComas is most excited to expand our knowledge of the heliosphere, which IMAP will sample by collecting passing solar particles and particles returning from the cosmic shield.

“We'll see the whole life cycle of these particles," he said. "We'll see them coming out from the Sun getting energized very locally, passing L1, and coming back in from the outer heliosphere boundary. It’s a really incredibly exciting mission, where we're able to do the entire life cycle of these particles and understand, I think for the first time, the holistic view of how this region of space around us, our solar neighborhood, really works. It's going to be a fabulous mission.”

McComas is on sabbatical this semester, and he will soon head to the Laboratory for Atmospheric and Space Physics (LASP) at the University of Colorado-Boulder, which will oversee IMAP's 10 instruments as they turn on in the coming weeks. Rankin, by contrast, is heading straight back to Princeton, where she is teaching McComas's annual space physics lab class.

Back on campus: “I was holding my breath”

On Princeton’s campus, a crowd of undergraduate and graduate students, faculty, staff, administrators and a handful of children watched NASA’s broadcast of the launch in rapt silence from an auditorium in Peyton Hall. 

“I was holding my breath,” said Teo Grosu, an astrophysics major from the Class of 2026 who had worked alongside NASA scientists in Princeton’s cleanroom as a student in the space physics lab class.

On campus, a rapt crowd watched NASA’s broadcast of the launch from an auditorium in Peyton Hall. 

Photo by

Denise Applewhite, Office of Communications

In the lab, Grosu had marveled at the intricacies of the instruments that launched into space today atop the Falcon 9 rocket. “It struck me how much of it is done by hand,” he said. John Teifert, one of the precision assembly specialists for the mission's Princeton-built SWAPI instrument, is an expert watchmaker.

Grosu was also surprised by the crowd that turned out for the early morning watch party. “What was really stunning is how many people were here at 7 a.m.,” he said. “People really do care about science.”

Robert Lupton, a senior research scientist in astrophysical sciences, emceed the watch party on behalf of the Department of Astrophysical Sciences and the Center on Science and Technology. “We want to congratulate Dave McComas and the IMAP team,” Lupton said. “Congratulations to everybody!”

Following the countdown and two critical burn stages that set the IMAP capsule on its trajectory into space, Lupton declared, “It looks like you're in business, IMAP!” and the crowd broke into applause.

Curiosity-driven science in service to the nation and humanity

In the days leading up to launch, the Kennedy Space Center Visitor Center hosted a series of briefings, public science talks and hands-on outreach activities linked to IMAP.

“What I'm most excited about is the things I don't know about,” McComas said during one of these briefings. “I know we're going to do a lot of great science — all the stuff we promised in the proposal: great new measurements, great new understanding. But the really exciting thing is when you fly new instruments that are much better than older instruments, you discover new things that you can't even imagine when you launch the spacecraft. That's really exciting.”

Several of the speakers emphasized the impact space weather has on everyday life. NASA’s Nicola Fox described a solar storm that erupted in 1972, between the Apollo 16 and 17 trips to the Moon. “It was so fast, and the solar radiation itself was so intense, that the impacts didn't just remain in space. The coronal mass ejection, or CME, as we call it, traveled from the Sun to Earth in a record-breaking 15 hours,” said Fox, associate administrator for NASA’s science mission directorate, during a briefing on Sept. 21. 

The enormous burst of solar particles and magnetic fields collided with Earth’s magnetic field, causing beautiful auroras as well as global electromagnetic problems. “The United States experienced radio blackouts, significant power grid disturbances, satellite damage” and other problems from magnetic disturbances, Fox said.

Another massive CME erupted in May 2024, bringing auroras down to low latitudes and severely degrading GPS satellites for several days. An unexpected consequence was to farmers, many of whom now depend on GPS navigation to precisely plant, fertilize and harvest their fields. With GPS systems unable to pinpoint their location, the farmers delayed planting, resulting in an estimated $500 million in crop losses to midwestern U.S. farmers.

“As the United States prepares to send humans back to the Moon and onward to Mars,” said Fox, “NASA science is actively providing the ultimate interplanetary survival guide to help support humanity's epic journey along the way.”

On the morning of launch, Fox was overjoyed. “It was amazing!” she said in NASA’s launch broadcast, moments after the rocket’s successful launch. “I have to admit, I completely cried. … There's so much on there. There's so much heliophysics and so much great NASA science.”

The Falcon 9 launches as day breaks in Florida.

Photo by Cory S. Huston/NASA