Legacy of the Apollo Seismic Experiments

Nunn, Ceri

doi:10.1007/978-3-319-05546-6_165-1

Cited by 3 publications

(4 citation statements)

References 37 publications

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“…All the Apollo seismic data were retrieved from the International Federation of Digital Seismograph Networks (Nunn, 1969). Every tool used in the preprocessing is provided by Nunn (2022). The event catalog of new moonquakes is provided by Onodera (2023).…”

Section: Appendix A: Supplementary Figures and Tablesmentioning

confidence: 99%

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New Views of Lunar Seismicity Brought by Analysis of Newly Discovered Moonquakes in Apollo Short‐Period Seismic Data

Onodera

2024

JGR Planets

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In the 1970s, two types of seismometers were installed on the nearside of the Moon. One type is called the Long‐Period (LP) seismometer, which is sensitive below 1.5 Hz. The other is called the Short‐Period (SP) seismometer, whose sensitivity is high around 2–10 Hz. So far, more than 13,000 seismic events have been identified through analyzing the LP data, which allowed us to investigate lunar seismicity and its internal structure. On the other hand, most of the SP data have remained unanalyzed because they include numerous artifacts. This fact leads to the hypotheses that (a) we have missed lots of high‐frequency seismic events and (b) lunar seismicity could be underestimated. To verify these ideas, I conducted an analysis of the SP data. In the analysis, I denoised the original SP data and performed the event detections by comparing the spectral features between the cataloged high‐frequency events (such as shallow moonquakes) and the continuous SP data. Eventually, I discovered 22,000 new seismic events, including thermal moonquakes, impact‐induced events, and shallow moonquakes. Among these, I focused on analyzing shallow moonquakes—tectonic‐related quakes. Consequently, it turned out that there were 2.6 times more tectonic events than considered before. Furthermore, additional detections of shallow moonquakes enabled me to see the regionality in seismicity. Comparing three landing sites (Apollo 14, 15, and 16), I found that the Apollo 15 site was more seismically active than others. These findings can change the conventional views of lunar seismicity.

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Section: Appendix A: Supplementary Figures and Tablesmentioning

confidence: 99%

“…For preprocessing, I corrected the sampling rate of the original Apollo data and filled the data gaps with linear interpolation. These processes can be performed with some programs provided by Nunn (2022). After that, the signals were detrended with a simple linear function.…”

Section: Data Set and Preprocessingmentioning

confidence: 99%

New Views of Lunar Seismicity Brought by Analysis of Newly Discovered Moonquakes in Apollo Short‐Period Seismic Data

Onodera

2024

JGR Planets

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“…This network, with 4 stations configured in an almost equilateral triangle, covered a portion of the lunar nearside with sensors to capture 3‐component mid‐period (MP) displacement (MHZ, MH1, MH2) and vertical‐component short‐period (SP) signal (Sutton & Latham, 1964). The MP sensors operated at a sampling rate of 6.625 Hz, with minor variations due to the Moon's significant temperature fluctuations (Nunn et al., 2017). There are 2 modes for PSE MP seismometer operations: peaked‐response mode (PRM) and flat‐response mode (FRM).…”

Section: Datamentioning

confidence: 99%

Newly Discovered Temperature‐Related Long‐Period Signals in Lunar Seismic Data by Deep Learning

Liu,

Xiao,

et al. 2024

Earth and Space Science

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Lunar seismic data are essential for understanding the Moon's internal structure and geological history. After five decades, the Apollo data set remains the only available one and continues to offer significant value for current and future lunar seismic data analyses. Recent advances in artificial intelligence for seismology have identified seismic signals that were previously unrecognized. In our study, we utilized deep learning for unsupervised clustering of lunar seismograms, leading to the discovery of a new type of long‐period lunar seismic signal that existed every lunar night from 1969 to 1976. We then conducted a thorough analysis covering the timing, frequency, polarization, and temporal distribution characteristics of this signal to study its properties, occurrence, and probable origins. This signal has a physical cause instead of artificial, such as voltage changes, according to its amplitudes during peaked and flat modes, as well as the digital converter status. Based on its relation to the lunar temperature and documents on Apollo instruments, we conclude that this signal is likely induced by the cyclic heater, with several unresolved questions that might challenge our hypothesis. Excluding interference from this newly identified signal is crucial when analyzing lunar seismic data, particularly in detecting lunar free oscillations. Our research introduced a new method for discovering new types of planetary seismic signals and helped advance our understanding of Apollo seismic data. Furthermore, the discovery of this signal holds valuable implications for the design of future planetary seismometers to avoid encountering similar issues.

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“…We download the 3-component long period Apollo seismic data from the GEOSCOPE observatory through the Insitut de Physique du Globe de Paris (IPGP) data center (http://datacenter.ipgp.fr/). The original data were stored on magnetic tape, but it has been extracted from binary to Standard for the Exchange of Earthquake Data format for easier access (Nunn, Weber, & Panning, 2020;Nunn et al, 2017). The data were recorded in two instrument response modes, flat and peaked mode.…”

Section: Data Selection and Initial Processingmentioning

confidence: 99%

Stresses in the lunar interior: insights from slip directions in the A01 deep moonquake nest

Turner

Hawthorne

Gaddes

2022

Preprint

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Legacy of the Apollo Seismic Experiments

Cited by 3 publications

References 37 publications

New Views of Lunar Seismicity Brought by Analysis of Newly Discovered Moonquakes in Apollo Short‐Period Seismic Data

New Views of Lunar Seismicity Brought by Analysis of Newly Discovered Moonquakes in Apollo Short‐Period Seismic Data

Newly Discovered Temperature‐Related Long‐Period Signals in Lunar Seismic Data by Deep Learning

Stresses in the lunar interior: insights from slip directions in the A01 deep moonquake nest

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