Instrument Development for Lunar Interior Investigation Using Atom Interferometry

The Atomic Lunar Seismometer (ALS) is an atom-interferometer instrument concept for measuring the lunar gravity and vibration modes at long time scales. Compared to other seismometer techniques, atom interferometers offer a pathway toward an ultra-low drift seismometer for signals around and below the mHz frequency range. The ALS instrument concept is also applicable to other terrestrial bodies such as Mars. In this paper, we present our instrument design based on a 5 cm tall atomic fountain and summarize the test results obtained in a laboratory environment. This development is specifically to optimize and accommodate in lunar environment. Presently, the instrument’s short-term sensitivity is 1.4 × 10⁻⁶ m/s²/$\sqrt{\mathrm{Hz}}$ (140 $\mathsf{\mu }$Gal/$\sqrt{\mathrm{Hz}}$), limited by the vibration noise in our lab, and it averages down to 6.7 × 10⁻⁸ m/s² (6.7 $\mathsf{\mu }$Gal) after 445 s.