Re-Evaluation of Lunar Seismograms
- Paper number
IAC-05-A3.P.19
- Author
Mr. Till Sonnemann, Deutsches Zentrum fur Luft und Raumfahrt e.V. (DLR), Germany
- Year
2005
- Abstract
The lunar seismograms recorded by the Apollo seismic experiment in the years 1969-77 were recently reviewed again by Y. Nakamura (2004). From 12558 detected events more than 7000 events were identified as deep moonquakes originating in depths between 700 and 1000km. The new survey by Nakamura (2004) identified about 250 regions with repeating sources, some of them are located on the far side of the moon where no quakes were found previously. This new catalogue is used in our study, which aims at locating far side deep moon quakes from seismogram stacks. Before stacking, a despiking scheme was applied. Errors due to bit flips in radio transmission can usually be identified by their amplitude. The damaged samples are set to zero. Thermal contraction often produces cracking sounds in the instruments which result in seismometer impulse response signals. These are identified by cross correlation with an idealized signal and removed by subtracting this ideal signal. Of all traces of one cluster, stack traces are computed as weighted mean of the individual events with weigths reflecting the signal quality. Wadati diagrams are drawn to check plausibility of arrival time readings and to get information about the vp/vs ratio. A 3D hypocenter determination using a nonlinear grid search method and an error representation according to the interval arithmetics concept is in work, and could be presented at the time of the IAF conference. By now a 2D prototype of this program is finished to locate the epicenters from Saturn V rocket stages to illustrate the planned concept. The reevaluated data could be useful to search for new landing sites of future space missions that will do seismic experiments on the moon. It could also offer a new interpretation of the moons interior, as we are still not being able to say if the moon has a core. And by the time of October hopefully there will be samples of the Lunar A seismic data published, to compare it with the old Apollo measurements.
- Abstract document
- Manuscript document
IAC-05-A3.P.19.pdf (🔒 authorized access only).
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