A NASA-sponsored team at the University of Iowa (UI) is making strides in restoring and advancing the United States’ capability to conduct high-fidelity magnetic field measurements. These measurements are crucial for investigating space weather phenomena that can affect both terrestrial communication and power grids, as well as space-based assets.
Fluxgate magnetometers, which are essential instruments in space science and space weather studies, rely on a critical component: a ferromagnetic core. Historically, these cores were developed for the U.S. Navy using technology that has since become inaccessible to the civilian sector. The UI team is now manufacturing new fluxgate cores using innovative methods that do not depend on these legacy processes or materials, integrating them into modern spaceflight magnetometers.
Revolutionizing Space Magnetometer Technology
The process of creating these ferromagnetic cores begins with base metal powders that are melted into custom alloys. These alloys are then rolled into thin foils, shaped into the desired geometry of the fluxgate core, and artificially aged through heat to refine their magnetic properties. The resulting cores are then incorporated into a complete fluxgate sensor, ready for spaceflight applications.
This in-house approach to designing, prototyping, and manufacturing cores, sensors, and paired electronics allows the team to explore new sensor geometries compatible with various missions. The most recent development is a new core for the Space Weather Iowa Magnetometer (SWIM). Although based on a core developed for the MAGIC Tesseract sensor, which launched on NASA’s TRACERS mission, the SWIM core is miniaturized while maintaining performance levels.
SWIM’s First Flight and Future Prospects
The SWIM fluxgate is set to have its first flight on the University of Oslo’s ICI-5bis sounding rocket mission, scheduled to launch in winter 2025/2026 from Norway’s Andoya Space Sub-Orbital range. Fluxgate magnetometers function by detecting the electromagnetic force induced by changing magnetic flux, allowing for precise magnetic field measurements.
Approximately 90% of the newly produced cores have a noise floor comparable to or better than previous legacy cores, enabling reliable mass production for SWIM and potential future missions.
Design Innovations and Enhancements
The SWIM magnetometer design introduces three significant changes compared to its predecessor, the MAGIC instrument. The sensor has been simplified and reduced in size, with a 30% decrease in sensor size and potential further reductions in mass as the design is optimized. This compactness aids in its accommodation on a magnetometer boom.
Additionally, the power consumption of the SWIM sensor has been halved by using three smaller cores with improved metallurgy, as opposed to six larger racetrack cores. This reduction in power consumption, although modest, positively impacts the capability for boom deployment by minimizing heat dissipation and thermal gradients.
Advanced Electronics for Enhanced Performance
The SWIM design also features an updated electronics topology. Unlike the MAGIC electronics, which used a traditional analog demodulator fluxgate and magnetic feedback design requiring high-performance components, the SWIM employs digital demodulation and temperature-compensated, digital pulse-width-modulation for magnetic feedback. This update allows SWIM to potentially be used in long-duration and high-reliability operational applications, such as radiation belt or planetary missions.
“The SWIM fluxgate design allows for more future applications in a variety of environments without sacrificing performance,” said Dr. David Miles, Project Lead at the University of Iowa.
Implications and Future Applications
The advancements in SWIM magnetometer technology represent a significant leap forward in space weather monitoring capabilities. The UI team’s efforts not only restore a critical technological capability but also enhance it, paving the way for more robust and versatile space missions. Upcoming flight opportunities for SWIM include missions on the Observing Cusp High-altitude Reconnection and Electrodynamics (OCHRE) and ICI5bis sounding rockets.
As the team continues to refine and improve their designs, the potential applications of these advanced magnetometers in various space environments grow, promising to enhance our understanding of space weather and its impacts on Earth and beyond.
Sponsoring this innovative project is the Heliophysics Strategic Technology Office (HESTO), underscoring NASA’s commitment to advancing space technology and exploration.
