Combined inertial and strain sensors for lunar seismology
- Paper number
IAC-09.B4.8.6
- Author
Mr. Kenneth Hurst, Jet Propulsion Laboratory, United States
- Coauthor
Mr. Michael Hecht, Jet Propulsion Laboratory, United States
- Coauthor
Dr. William Bruce Banerdt, Jet Propulsion Laboratory, United States
- Coauthor
Mr. Thomas Pike, Jet Propulsion Laboratory, United States
- Year
2009
- Abstract
A lunar passive seismology station must land, mechanically couple the seismometer to the ground, and then operate for an extended period of time (several years). One such mode of landing and deployment involves a penetrator that inserts the seismometer into the lunar regolith under high velocity and high acceleration. Sensors with small mass and size are at an advantage for packaging to withstand high G loads and for minimizing power consumption. On the other hand, an inherent physical limitation of small inertial sensors is that it is difficult to design them and their associated electronics to have good long-period response (greater than 30 seconds) and high sensitivity (10-9 G). A strain-based seismic sensor and its electronics can have good response from 10s of Hz all the way out to DC (months and years) and is usually limited by the quality of the mechanical coupling to the surrounding material, not by the instrument itself. A combination of an inertial sensor with a strain-based sensor can cover the spectrum from 1 kHz to DC, and is compatible with miniaturization and shock hardening. A microseismometer with 4x10-8 ms-2(Hz) -1/2 sensitivity down to about 25 seconds and the ability to be hardened to 15,000 Gs has been demonstrated by Dr Tom Pike. Borehole strainmeters exist that are capable of measuring 10-9 strain from above 20 Hz to DC. Furthermore, the combination of inertial and strain data can enable new investigations not possible with only inertial sensors. A tri-axial strainmeter operating near the free surface can yield the full 9-component strain tensor. The combination of inertial and strain data from a single instrument can yield the local 3D seismic phase velocity directly for the frequency band of overlap. This can enable investigating bulk physical properties of the surrounding material including estimates of anisotropy, which in turn can be interpreted in terms of preferred crystallographic orientations and possible deformation mechanisms.
- Abstract document
- Manuscript document
IAC-09.B4.8.6.pdf (🔒 authorized access only).
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