TRACERS satellites set to explore solar magnetic reconnection near Earth

TRACERS satellites set to explore solar magnetic reconnection near Earth
by Clarence Oxford
Los Angeles CA (SPX) Jul 22, 2025

NASA is preparing to launch the Tandem Reconnection and Cusp Electrodynamics Reconnaissance Satellites (TRACERS) mission on July 22 from Vandenberg Space Force Base in California. Led by the University of Iowa and supported by Southwest Research Institute (SwRI), the mission aims to investigate how the Sun's and Earth's magnetic fields interact.

SwRI contributed scientific leadership and developed the Analyzer for Cusp Ions (ACI) instruments, which will operate aboard both TRACERS spacecraft. These identical satellites will enter low Earth orbit to collect data during over 3,000 crossings of the Earth's north polar magnetic cusp, offering a unique perspective on magnetic reconnection events that influence space weather.

"TRACERS has two identical satellites outfitted with five instruments, each to collect data from over 3,000 cusp crossings during its one-year primary mission," said Mark Phillips, deputy project manager at SwRI. "By observing from two points along the orbit, the mission offers a multidimensional view of these reconnection events, providing crucial insights into how solar wind conditions impact the magnetosphere. This information is vital to understanding space weather phenomena that can disrupt satellite operations, communications and power grids on Earth."

These observations will help scientists explore how magnetic reconnection-where magnetic field lines rapidly link and reconfigure-alters the near-Earth space environment. The cusp region, where Earth's magnetic field lines bend downward near the North Pole, serves as an ideal location for this research.

"TRACERS is an exciting mission," added Dr. Stephen Fuselier of SwRI, deputy principal investigator and ACI lead. "We flew NASA's TRICE-2 rockets in 2018 as a part of the international, multimission 'Grand Challenge Initiative - Cusp observational campaign. The data from that single pass through the cusp were amazing. We can't wait to get the data from thousands of cusp passes."

The TRACERS mission complements the earlier Magnetospheric Multiscale (MMS) mission, also led by SwRI, which provided microscale insights into magnetic reconnection. This follow-up effort will allow researchers to examine how reconnection varies spatially and temporally using high-resolution energy-angle data captured by the ACI sensors every 0.3 seconds.

"Based on a standard top-hat electrostatic analyzer design, the ACI sensor measures energy-angle distributions every 0.3 seconds with excellent energy resolution and high-cadence coverage," Fuselier explained. "By measuring how energy disperses separately by both TRACERS spacecraft, we can determine the nature of reconnection variability. If the changes occur at the same latitude on both spacecraft, then reconnection is spatially variable. If the changes occur at different latitudes, then reconnection is temporally variable."

By integrating TRACERS data with findings from SwRI's upcoming PUNCH mission, scientists expect to gain deeper understanding of how solar energy moves from the Sun into Earth's magnetosphere and atmosphere.