TRACERS

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TRACERS, short for Tandem Reconnection and Cusp Electrodynamics Reconnaissance Satellites, is NASA’s two-satellite mission to study how the Sun’s solar wind interacts with Earth. The pair of identical, spinning spacecraft observe the magnetosphere, especially near the northern magnetic cusp, to understand magnetic reconnection and how solar particles can impact our planet and technology.

The two TRACERS spacecraft fly in a low Earth, polar orbit about 600 km above the surface. They were built by Millennium Space Systems and launched on July 23, 2025, aboard SpaceX’s Falcon 9 rocket from Vandenberg Space Launch Complex 4. After launch, the satellites were deployed within minutes of liftoff, with SV1 and SV2 following different deployment times.

TRACERS was proposed by Craig A. Kletzing of the University of Iowa, who served as Principal Investigator until his death in 2023. David M. Miles of the University of Iowa became PI afterward. The mission received about $115 million in NASA funding and is part of NASA’s Small Explorer (SMEX) program. It was initially planned as a partner to another mission, PUNCH, which studies the solar wind; TRACERS focuses on Earth’s response to those solar particles.

In the early days after launch, NASA paused commissioning on July 25 to investigate a power-subsystem issue affecting one satellite. By September 11, 2025, NASA confirmed that communication was restored with SV1, while SV2 completed post-launch commissioning without issues.