Lunar Seismometer and Burial System

Date: 4/25/2019

Time: 06:00 PM

Room: Fifth Avenue

Beginning in 1969, Apollo successfully deployed a long-lived network of seismometers on the Moon, which resulted in the only substantial seismic data set of another planet currently in existence. Many questions remain regarding the frequency and distribution of natural moonquakes. In particular, due to the exclusively near-side installation of the Apollo seismometers, it is currently unknown whether the far side of the Moon is aseismic. This translates into an incomplete understanding of the Moon’s hemispherical dichotomies in crustal thickness, mare volcanism, and the distribution of heat-producing elements. A primary challenge to a future Lunar Geophysical Network mission is that the Moon is covered with a remarkably low-density regolith layer. The powdered surface regolith layer has very low P-wave seismic velocities - less than 50 m/s within the top 1 m. The regolith causes increased near-surface trapping and scattering of seismic waves effectively masking distant and low magnitude quakes.

To overcome the challenge presented by the regolith, our team is developing a novel lunar seismometer and burial system based on the Silicon Audio 3-axis seismometer and the Honeybee Robotics burial system. The effects of noise from the surface can be mitigated by deploying instruments below the scattering layer. A lander, which cannot be entirely shielded from the sun, will continuously expand and contract with the diurnal cycle. This thermal stressing creates noise at many frequencies that will contaminate seismic signals of interest for a robotically deployed surface seismometer. To realize the benefits of sensor burial, Honeybee provides a low-mass, low-power burial system developed for a NASA-funded lunar Heat Flow Probe. The system uses pressurized gas to create a vertical hole in the regolith, into which the instruments are then placed. We are merging this system with our Silicon Audio seismometer, an instrument that meets the sensitivity requirements for lunar science and is self-leveling, low in mass, volume and power.

Presenting Author: Renee C. Weber

Authors