Above: A photo from the surface of the moon, where the BU-built LEXI telescope enables the study of Earth’s magnetic forces. Courtesy of Firefly Aerospace
In a historic first for the University, the LEXI telescope imaged Earth’s magnetic shield from the lunar surface
It was one small step for Boston University. And one giant leap for our understanding of the Earth’s magnetic shield.
In the early hours of Sunday, March 2, 2025, a Boston University research team gathered at the College of Engineering for a historic moment: the first-ever BU-built device was landing on another planetary body. The Lunar Environment heliospheric X-ray Imager (LEXI) had hitched a ride aboard NASA’s Blue Ghost Mission 1 to the moon.
Funded by the national space agency in 2019, LEXI was years in the making, designed to capture X-ray emissions created when solar particles collide with atoms in Earth’s outermost atmosphere. The images would offer a first-of-its-kind look at the planet’s magnetic shield, our key defense against space radiation.
Once the mission touched down on a flat region called Mare Crisium, LEXI was powered up. Back on Earth, Associate Professor of Mechanical Engineering Brian Walsh (GRS’09,’11), LEXI’s lead scientist, and his team opened the telescope’s front latch, exposing its lenses to space and breathing a sigh of relief that it had survived the trip intact.
“LEXI [imaged], for the first time, the X-ray signature to monitor the boundary of Earth’s magnetic field,” Walsh says, and how it deflects the constant flow of solar wind and high-speed charged particles from the sun.
“Lexi [imaged], for the first time, the boundary of Earth’s magnetic field.”
But time was of the essence. BU scientists worked around the clock, analyzing real-time data to ensure the instrument functioned properly. They had just one week before the onset of the moon’s nightfall when temperatures plunged to -208°F, permanently disabling the lander and all its experiments.
LEXI’s mission may have been brief, but its insights could help protect our planet for decades to come.