Chip-Scale Atomic Magnetometers for Space Science

Abstract:

Since the 1960s, atomic magnetometers have been a key instrument on select space missions in Earth orbit and to other planets. Using an orbiting platform, information about the interior structure and evolution of planets and other bodies can be inferred from measurements of dynamo, induced, and crustal magnetic fields. In addition, the interaction of the planet with the local solar wind and/or magnetospheric environment can be observed and studied. Atomic magnetometers offer unique characteristics over other types of magnetometers, such as exceptional long-term stability, intrinsic accuracy and are able to measure the magnitude of the field, rather than its vector components. Therefore, these instruments constitute excellent references for high-accuracy magnetic field mapping missions and for inflight calibration of vector magnetometers during long-life missions. Historically, such instruments have been several liters in size, have had a mass of several kg and consumed several Watts of power.

Over the last 15 years, a new generation of highly miniaturized atomic magnetometers has been developed based on advanced diode lasers and silicon micromachining. Because of the small size of the vapor cell containing the atoms and the removal of the discharge lamp, the power consumption of the physics package can be reduced to a few 10’s of mW, and the size to a few cubic millimeters. Combined with modern, low-power electronics, atomic magnetometers can operate on as little as 100 mW of power and are therefore suitable for deployment on the increasing number of low-cost, resource-constrained space platforms such as cubesats and chipsats. Even at ten times this power, these instruments become attractive additions to any planetary mission targeting magnetic field measurements either by themselves or in combination with other vector magnetometers. We will discuss some technical details of these new instruments, show results from a recent flight demonstrating on a sounding rocket, and speculate on new opportunities for planetary science and fundamental physics enabled by this new technology.