Standing on Apollo’s Shoulders: a Microseismometer for the Moon

Seismometers deployed on the Moon by the Apollo astronauts from 1969 to 1972 detected moonquakes and impacts and added to our understanding of the lunar interior. Several lunar missions are currently being planned, including the Commercial Lunar Payload Services (CLPS), the Lunar Geophysical Network (LGN) and the astronaut program Artemis. We propose a microseismometer for the Moon: the Silicon Seismic Package (SSP). The SSP’s sensors are etched in silicon, and will have a noise floor below 2x10−10m/s2/√Hz between 0.03 and 3 Hz (similar to the Apollo instruments). The SSP will measure horizontal and vertical motion with the three sensors in a triaxial configuration and is robust to high shock (>1000g) and vibration (>30grms) with an operational range from -196Cto +60C, allowing deployment under harsh conditions. The first-generation version of this sensor, the SEIS-SP, was deployed on Mars in 2018 as part of the InSight mission’s seismic package. We will reconfigure the seismometer for the lower gravity of the Moon. At this level of performance, the limiting factor for detecting smaller moonquakes is the noise environment of the Moon. Using the Apollo seismic data, we estimate that a single SSP instrument operating for one year would detect around 74 events above a signal-to-noise ratio of 2.5, as well as an additional 500+ above the noise floor.A mission lasting from lunar dawn until dusk, carried on a CLPS lander, could test the instrument in-situ, and provide invaluable information for an extensive future network.