A NASA-Sponsored Effort Revives a Critical Space Instrument
Under a NASA-sponsored program, a University of Iowa (UI) team is restoring and advancing the nation’s ability to measure magnetic fields with high fidelity. These measurements are essential for understanding space weather and its potential to disrupt Earth-based communications, power grids, and spacecraft operations. At the heart of this effort are fluxgate magnetometers, instruments that have long served space science but relied on a legacy ferromagnetic core technology developed for the U.S. Navy and since lost to civilian supply chains. The UI team is changing that by manufacturing new, modern cores and integrating them into next-generation spaceflight magnetometers.
From Legacy Loss to Modern Core Manufacturing
Traditional fluxgate cores were forged using processes and materials now unavailable to civilian researchers. The UI approach begins with base metal powders that are melted into custom alloys, rolled into thin foils, and formed into the precise geometry required for the core. An artificial aging heat treatment tunes the magnetic properties to optimize performance. The resulting cores are then embedded in complete fluxgate sensors prepared for spaceflight.
Designing, prototyping, and manufacturing the cores, sensors, and paired electronics in-house gives the team a unique ability to explore new sensor geometries and tailor the instruments to different missions. The most recent achievement is a new core design for the Space Weather Iowa Magnetometer (SWIM). While the SWIM core builds on a design developed for the MAGnetometers for Innovation and Capability (MAGIC) Tesseract sensor—now flying on NASA’s TRACERS mission—the UI version is miniaturized without sacrificing performance. The first flight opportunity for SWIM is on the University of Oslo’s ICI-5bis sounding rocket mission scheduled for winter 2025/2026 from the Andøya Space Sub-Orbital range in Norway.
SWIM: A Miniaturized, Low-Power Instrument for a Range of Missions
Fluxgate magnetometers detect magnetic fields by measuring the electromotive force induced by changing magnetic flux. In operation, current is driven through the drive winding inside the core, creating a magnetic field. The core’s ferromagnetic material changes its permeability in response to the external magnetic field, inducing a signal in the sense winding. By comparing the drive current with the sense winding output, researchers infer the ambient magnetic field. In many missions, magnetometers are placed on booms to minimize interference from spacecraft electronics and onboard materials.
The SWIM iteration is designed to be compact and power-efficient. The three-core SWIM sensor mirrors the geometry of the MAGIC cores but uses smaller units to achieve similar performance with reduced mass. The move to a lighter, smaller core set opens the door for deployment on smaller satellite booms and less demanding spacecraft geometries.
Three Key Improvements: Size, Power, and Electronics
Reduced Sensor Size. The SWIM design shrinks the sensor by roughly 30% compared with MAGIC. In a notable engineering choice, the team uses three smaller cores rather than six racetrack cores, enabling a smaller footprint and lower mass. A carbon-composite outer cover is optional, contributing to an overall sensor mass of about 110 grams. This lighter, sleeker footprint makes SWIM well-suited for compact satellite booms where every gram matters for attitude control and stabilization.
Reduced Power Consumption. The move to three smaller cores paired with improved metallurgy cuts power usage roughly in half relative to MAGIC. While a smaller consumption footprint is beneficial in any instrument, the reduction also eases heat management on deployable booms. Less heat dissipated at the sensor means fewer thermal gradients that could perturb the boom’s shape and pointing accuracy, all while maintaining the same level of measurement fidelity. Early miniaturized SWIM cores even outperform their MAGIC predecessors thanks to their refined metallurgy.
Updated Electronics Topology. MAGIC relied on an analog demodulation approach and sensor-driven magnetic feedback that demanded high-performance, radiation-tolerant components. SWIM adopts digital demodulation and employs temperature-compensated, digital pulse-width modulation to drive magnetic feedback. This shift enhances reliability in high-radiation environments and makes SWIM a stronger candidate for long-duration missions such as radiation belt studies or planetary explorations with extended cruise phases.
Flight Opportunities and the Path Forward
The SWIM design is not merely theoretical. UI’s manufacturing pipeline is now well documented and product-ready, allowing scalable production for SWIM’s payloads and future missions. The team envisions multiple flight opportunities, including on the Observing Cusp High-altitude Reconnection and Electrodynamics (OCHRE) mission and the ICI-5bis sounding rocket. These opportunities will validate the sensor on real missions and push toward broader adoption of the technology in space weather campaigns and beyond.
Production Readiness and Impact on Space Weather Science
With about 90% of produced cores achieving a noise floor comparable to or better than legacy cores, the UI team can reliably manufacture cores at scale for ongoing and future missions. The SWIM sensor’s compact design, reduced power needs, and resilient electronics topology position it to support a new generation of magnetometer booms—crucial for clean magnetic field measurements in space weather research and for safeguarding Earth’s technological infrastructure.
Leadership, Sponsorship, and Collaboration
Project Lead: Dr. David Miles, University of Iowa. Sponsoring Organization: Heliophysics Strategic Technology Office (HESTO). The collaboration fuses university innovation with NASA program goals to maintain and advance high-fidelity magnetic field measurements essential for space weather forecasting and mission design.
