Soaking up the sun

Across our solar system, supersonic winds of charged particles from the sun blow at a million miles per hour. These winds form a protective bubble around our entire solar system that shields us from galactic radiation. However, this space weather can disrupt satellite communication and navigation systems, and can cause power outages here on Earth.

At the Princeton Space Physics laboratory, the lead institute for several NASA missions and instruments, researchers study the heliosphere — the extension of the sun’s atmosphere into space. Their goal is to help protect the people and technology we send into space, and give insights into how the universe works on broader scales.

“Most universities don’t have the ability to build a flight instrument for NASA,” said David McComas, who heads the Space Physics group and is a professor of astrophysical sciences and vice president of the Princeton Plasma Physics Laboratory. “It’s a really special thing for Princeton.”

The lab is building one of the instruments that will travel on NASA’s Interstellar Mapping and Acceleration Probe (IMAP), set to launch in 2025, for which McComas is the principal investigator and Princeton its lead institution.

The spacecraft is being built at the Johns Hopkins Applied Physics Laboratory in Maryland, while the other instruments are being built at various locations throughout the United States and Europe.

The IMAP mission will investigate two of the most important issues in space physics — how particles from the sun accelerate and travel through space, and the effects of these particles on our solar system.

The device being developed at Princeton, called the Solar Wind and Pickup Ion (SWAPI) instrument, will measure the solar wind and interstellar pickup ions, produced from cold neutral atoms drifting in from the surrounding interstellar medium.

As part of its mission, the lab provides opportunities for undergraduate and graduate students to solve real-world problems in an active space instrument laboratory. The emphasis on education, McComas said, sets this lab apart from most others in the country.

“Providing that opportunity for the students who are interested in more experimental work is very high on my list,” McComas said. “I have responsibilities to NASA to build instruments, and I am always striving to find the educational synergy there.”

One student contribution involved ultrathin carbon foils, an essential piece of many space instruments, including the IMAP mission’s SWAPI instrument. To install a foil in an instrument, researchers must first float the foil onto a metallic flight grid in a process known as foil floating. Variations in foil floating influence the quality of foils, thereby altering the performance of space instruments.

Last year, two students designed a standardized foil floating process to improve space mission outcomes for their joint undergraduate-master’s thesis project. The procedure, developed by Grace Gong, undergraduate Class of 2022, and Nina Arcot, who earned her master’s in mechanical and aerospace engineering in 2022, is now used at the Space Physics lab and can be adapted for use by other institutions worldwide. “We’re directly using this development from the student work to make a better instrument than we would have made otherwise,” McComas said.

Jamie Rankin is an associate research scholar and the instrument lead for SWAPI. She collaborates with McComas in overseeing the Space Physics laboratory and the corresponding class for undergraduates at Princeton. “We aim to provide students the most realistic, hands-on, practical experience in the lab that we can,” Rankin said.

Rankin’s research combines measurements from the Voyager mission, launched in the 1970s, with the more recent Interstellar Boundary Expedition (IBEX) mission’s all-sky observations to investigate interactions between the heliosphere and the interstellar medium. She also studies the behavior of cosmic rays in the very near-sun environment using observations from another NASA mission, the Parker Solar Probe.

Only a limited number of organizations in the country build space instruments, and most of them are not educational institutions. For this reason, McComas and his team are working to create a program that will continue to train scientists and engineers for many years to come.

Rankin said she looks forward to seeing current and future space instruments built in the Princeton lab, and that now is only the beginning of a longer, more gratifying endeavor. “It is truly an honor to play some small role in exploring, discovering and understanding some of the mysteries of the universe,” she said.