A grapefruit-sized quantum device mapped Earth’s magnetic field from space

An imperfect diamond is perfect for sensing Earth’s magnetic field from space.

A quantum device used a diamond’s defects to map Earth’s magnetic field from the International Space Station. Just 10 centimeters on a side, OSCAR-QUBE reveals the potential of the technology. It performed consistently over 10 months of data taking in 2021 and 2022, and its measurements agreed with a previous estimate of the magnetic field, engineer Jaroslav Hruby and colleagues report in a paper published May 7 in Physical Review Applied.

Space-based measurements of Earth’s magnetic field typically require bulky satellites. Quantum sensors can be smaller, while also being more sensitive and operating more stably, among other benefits.

OSCAR-QUBE’s sensor is made of a lentil-sized piece of diamond with defects in its lattice of carbon atoms, in which a carbon atom is missing and a neighboring carbon is replaced by a nitrogen. The defects act like quantum particles, with energy levels similar to an atom’s. Magnetic fields alter the energy levels of the defects. That means variations in the strength of the Earth’s magnetic field from place to place can be detected by measuring the light emitted when the diamond is hit with laser light and microwaves.

“Earth’s magnetic field is actually very fascinating to measure, because it contains a lot of information,” says Hruby, of Hasselt University in Belgium. Motions within Earth’s molten outer core, the rocks in the crust, space weather and ocean tides all affect the magnetic field. Maps of the magnetic field can even be used to navigate, for example, when GPS is not available.

The device’s performance didn’t yet beat out the most advanced conventional magnetometers. But a future mission will have upgraded quantum hardware, and will make measurements from outside the space station, instead of inside, where the internal magnetic fields limited its capabilities.