Originally published at: NASA's abandoned lunar lander is causing moonquakes | Boing Boing
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Humans, eh? Managed to f*ck up two planetary bodies and they’re hardly started yet…
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Paper is here.
https://agupubs.onlinelibrary.wiley.com/doi/epdf/10.1029/2022JE007704
Interesting that they included a plain language summary.
Abstract Thermal moonquakes are recurring seismic signals detected on the lunar surface that are temporally correlated with the lunar day-night cycle, although their precise mechanism is not known. The Lunar Seismic Profiling Experiment (LSPE) was a deployment of four geophones during the Apollo 17 mission to characterize the near-surface structure of the landing site using explosive shots. The array was reactivated in passive recording mode several times after the mission was completed and recorded thousands of thermal moonquakes. In this study, we expand on an initial detection catalog and determine waveform parameters and source information for the seismic signals. We used a spectrogram-based approach to obtain fine-tuned arrival times, quantify the envelope length using emergence, and compute peak-ground-velocity. We obtain the incident azimuth direction by applying stochastic gradient descent to a travel-time misfit equation. We found that thermal moonquakes are split into two main classes: (a) impulsive, high-amplitude events that are produced by the lunar module descent vehicle located east of the LSPE array in response to rapid temperature transitions during sunrise and sunset and (b) emergent events, that are natural responses to incident sunlight whose duration is directly linked to the temperature of the regolith. We hypothesize that the correlation between temperature and emergence could be due to changes in regolith scattering or higher energy daytime events occurring further away.
Plain Language Summary Thermal moonquakes are a frequent seismic activity on the moon. We know that the quantity of these events is linked with the 30-day lunar day-night cycle, but a mechanism that explains how these vibrations are generated is not known. These signals are important because they provide clues on lunar surface processes including crater deformation and lunar soil production. Thousands of these signals were recorded during an 8-month span from 1976 to 1977 on four seismometers deployed during the Apollo 17 Lunar Seismic Profiling Experiment, but the poor quality of data makes analysis difficult. We developed algorithms to accurately determine the arrival timing of the waves, measure the strength of the seismic signal, and find the direction of the moonquake source. We found that impulsive moonquakes are not due to natural processes, but are vibrations generated from the lunar module descent vehicle left by the astronauts in 1972. The duration of the non-impulsive events is correlated with temperature: the hotter the temperature, the longer the seismogram. We think that this behavior might be due to changes in regolith properties or stronger events during the day.
(any OCR errors are a necessary consequence of DRM.)
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These guys are not happy about it
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“Tranquility Base ––
There goes the neighborhood
American garbage dumped in space
And no room left for brotherhood.”
– “Have You Seen the Saucers?”, Jefferson Airplane
I’m trying to figure out what the problem is here. Are they suggesting the thermal expansion of any spacecraft on the Moon poses a danger to Moon geology & stability?
Or did they discover unexpected thermal expansion issues with the way they built the ship and that has implications for future missions?
My house shakes when a bus drives by, but life goes on.
any vibrations will stress a structure if that structure isn’t built to accommodate those vibrations. those stresses could lead to cracking or worse. ( see also: earthquakes )
your house exists to block some wind and rain mainly. a ummm moon house needs to keep oxygen in and not explosively decompress
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