A team of researchers used tiny imperfections on a diamond lattice to successfully measure Earth’s magnetic field. The quantum device, called OSCAR-QUBE, measures just 10 centimeters (3.9 inches) on each side. At its core is a small, lentil-sized diamond that detects magnetic-field changes through its defects.

OSCAR-QUBE operated reliably aboard the International Space Station (ISS) for 10 months in 2021 and 2022. It demonstrated the promise of quantum magnetometers that could eventually circle our planet aboard small satellites.

Measuring Earth’s magnetic field from space

Traditional space-based magnetic field measurements often rely on large satellites that can be extremely expensive to lift to Earth’s orbit. Increasingly, researchers are focusing on quantum sensors, as they could enable smaller form factors while still providing stronger sensitivity and better operational stability.

OSCAR-QUBE’s core is a small diamond containing nitrogen-vacancy (NV) centers. These are lattice defects introduced when a carbon atom is absent, and a neighboring one is replaced by nitrogen. They essentially behave like small quantum systems, or quantum particles, whose energy levels shift in response to magnetic fields.

According to the team behind the experiment, their 2021-2022 OSCAR-QUBE readings aligned with prior estimates of Earth’s magnetic field. They conducted the experiment by illuminating the diamond with laser light and microwaves.

This allowed them to detect changes in the emitted light, corresponding to variations in the Earth’s magnetic field strength. Using this method, they were able to map spatial differences in Earth’s field from orbit.

The mysteries of our magnetic field

Scientists don’t fully understand Earth’s magnetic field. Though they know it is influenced by convective motions in the planet’s molten outer core, they cannot fully explain its rapid, unpredictable changes, or why it has been very gradually weakening for roughly 200 years.

Accurately mapping the field could provide answers to those unknown questions. It could also improve navigation in GPS-denied environments and shed light on geophysical processes. “Earth’s magnetic field is actually very fascinating to measure, because it contains a lot of information,” study lead Jaroslav Hruby of Hasselt University in Belgium, explained in a report by Science News.

The scientists noted that the OSCAR-QUBE experiment’s performance did not surpass that of state-of-the-art conventional magnetometers. Crucially, though, it validated the technology in a real space environment. Further experiments will help to collect more data and improve performance. 

Though the team collected valuable data, they noted that measurements were taken from inside the ISS, where magnetic fields from equipment caused some interference. A follow-up mission will use improved quantum hardware positioned outside the station for cleaner data.

As hardware improves, quantum magnetometers could become standard components in future satellite constellations, delivering high-resolution magnetic data with compact payloads that are much cheaper to lift into orbit.

The research was published in the journal Physical Review Applied.