Satellites launching from California could help scientists understand disruptive space weather

San Francisco Chronicle​

22-07-2025

Two twin satellites — part of NASA's TRACERS mission — set to launch tomorrow at Vandenberg Space Force Base will help scientists better understand space weather.
Researchers expect the mission to provide new insights into how charged particles from the sun plow into Earth's magnetic shield. Such interactions underlie the dazzling northern lights, like the brilliant light shows that swept large swaths of California in 2024.
'What we will learn from TRACERS is critical for the understanding and eventually the predicting of how energy from our sun impacts the Earth,' said Joe Westlake, director of NASA's heliophysics division, during a briefing July 17. 'It's going to help us keep our way of life safe here on Earth.'
The explosion of energy can also wreak havoc on satellites and power grids. Data collected by the TRACERS mission could aid future aurora forecasts and also inform preparations ahead of damaging geomagnetic storms.
Two identical satellites will capture data on how a steady stream of charged particles from the sun, also known as solar wind, enters the near-Earth environment. This process is known as magnetic reconnection.
High solar wind speeds can bring geomagnetic storms while slow wind speeds bring calm space weather. Fast solar winds can also cause auroral displays. The most expansive displays, like those above California in 2024, are typically associated with coronal mass ejections, large expulsions of charged particles and magnetic fields from the sun.
Solar winds carry the sun's embedded magnetic field, reaching speeds over one million miles per hour. Earth's magnetosphere, a region dominated by the planet's magnetic field, acts as a protective bubble deflecting the solar wind and shielding Earth from solar radiation.
The twin satellites, each slightly larger than a washing machine,will fly through a narrow region in Earth's magnetic field known as a polar cusp, where solar wind funnels into Earth's atmosphere. Over a year, the spacecraft will make 3,000 passes through the northern polar cusp.
The reason for two satellites, rather than just one, is to probe how magnetic reconnection occurs in space and time. The two TRACERS spacecraft will follow each other in orbit, creating closely spaced snapshots that will help scientists tease apart how quickly changes in plasma, or charged particles from the sun, occur.
The two satellites carry scientific equipment provided by UC Berkeley, UCLA and other institutions. UC Berkeley's instruments sense electricity within the magnetized plasma of near-Earth space, said David Miles, an associate professor of physics and astronomy at the University of Iowa and principal investigator of the TRACERS mission, by email. UCLA's instruments work like extremely sensitive compasses and measure the strength and direction of the local magnetic field.
'These instruments from Berkeley and UCLA are crucial for decoding the complex interactions in our planet's space environment and the magnetic reconnection process that couples in energy from the solar wind,' Miles said.
Decoding such interactions is important for life closer to the surface. The historic storm in May 2024 that led to aurora viewings in California impacted air travel: Transoceanic flights were rerouted due to high-frequency radio loss, Westlake said. The event also caused roughly $500 million in economic losses in the agriculture sector, due to precision GPS issues, Westlake added.
'TRACERS joins the fleet of current heliophysics missions that are actively increasing our understanding of the sun and space weather and how to mitigate these impacts,' Westlake said.