29:
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background level. There was great variability in their character and occurrence, being detected by both the long-period and short-period seismometers. This type of signal was detected 83 times during the Apollo 11 missions at an average of 4 per day. The origins of these signals were suggested to be either meteoroid impacts or shallow
242:
Moon would have a continuous level of meteoroid impacts that would result in a high background noise, but this was similarly disproven. The most significant hypothesis these observations led to was the knowledge that the Moon was absent of any of the significant tectonic processes observed in the Earth's crust.
241:
The background seismic levels on the Moon were found to be very low, far lower than that measured by any known instrument on Earth at the time. While there are large thermal variations due to the diurnal cycle, this does not result in a high background noise. A different hypothesis suggested that the
232:
The seismometers were particularly affected by the amount of seismic noise that emanated from the Lunar Module. This seismic noise was the result of venting, fluid circulation, and the Lunar Module's response to changes in temperature. Future missions would seek to deploy seismometers at the farthest
284:
were hypothesized to originate from the Lunar Module itself, being caused by the circulation of gas or liquids through the vehicle and in the portable life-support systems. These signals saw an increase in their predominant frequency during the Lunar Module's time on the surface and it is suggested
249:
were the only signal classification with a hypothesized lunar surface origin, and with their main characteristics being described as having a long duration (<1 hour) and an emergent initiation. These events would produce a signal that would build up slowly to its peak and then slowly fade to the
228:
The instrument temperature reached a maximum of 190 °F (88 °C), 50 °F (28 °C) greater than the expected maximum of 140 °F (60 °C). This higher than expected temperature resulted in minor effects such as intermittent transient signals on the low frequency seismometers,
273:
climbed the module's ladder. The predominant frequency of many type A signals was possibly caused by resonance from the Lunar Module. Items that were either consumable or simply unnecessary for the return journey were ejected from the Lunar Module as trash, forming the first lunar "toss zone" in
268:
were anthropogenic in origin. While the Apollo 11 astronauts were present on the Moon, the PSEP detected many seismic signals in relation to their activities, mainly on the short period/high frequency vertical seismograph. This included the astronauts' footfalls on the lunar surface, or when in
229:
but did not significantly affect instrument performance. The low frequency seismometers drifted out of their operating range on the last two days and could not be recalibrated because the package could not receive commands.
182:. Due to reduced payload capacities and NASA's decision to prioritize experiments that would provide transferable knowledge related to crewed landings on the Moon, the probes did not carry seismometers.
262:
were suggested to be the result of either the relief of stresses in the vehicle due to heat expansion or the result of micro-meteoroids impacting either the Lunar Module or the experiment package.
720:
225:
on July 21, 1969. A set of 15 different commands could be sent to the experiment package from mission control on Earth to direct the instrument's levelling and calibration motors.
485:
Latham, Gary V.; Ewing, Maurice; Press, Frank; Sutton, George; Dorman, James; Nakamura, Yosio; Toksöz, Nafi; Wiggins, Ralph; Derr, John; Duennebier, Frederick (January 30, 1970).
751:
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Power to this experiment was provided by EASEP via solar cell panels and operations of the experiment were limited to the lunar day. On later Apollo missions as part of
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The experiment was terminated on August 27, 1969, when the experiment package failed to receive and execute commands from Earth.
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92:
371:
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Latham, L; Ewing, M; Press, F; Sutton, G; Dorman, J; Nakamura, Y; Toksov, N; Wiggins, R; Derr, J; Duennebier, F (1970).
155:
102:
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three low-frequency seismometers in an orthogonal triaxial arrangement to capture horizontal and vertical movement.
251:
604:
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had been part of multiple prior attempts to measure the Moon's seismic activity, providing instruments on
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on these missions failed to reach their destination successfully. Separately, a research group at the
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close proximity to both the lander and the PSEP. Some of those items, such as armrests and portable
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139:
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8:
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278:, when striking the lunar surface, generated seismic signals detected by the instrument.
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that this was the result of the use of consumables through the mission duration.
122:) was a scientific experiment deployed on the lunar surface by the astronauts of
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one single-axis high-frequency seismometer that only measured vertical motion.
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65:
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were long in duration with large amplitudes but with similar spectra to
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28:
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had developed a seismometer to fly on landers that were part of the
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Seven types of signals were identified by the instrument package.
194:, power was provided to those packages' seismic experiments via a
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The PSEP was placed 16.8 meters (55 ft) from the Apollo 11
130:(EASEP). The experiment's goal was to determine the structure,
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direct physical contact with the Lunar Module including when
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135:
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713:"The Apollo 11 astronauts left a lot of junk on the Moon"
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605:"Meteoroid impacts as sources of seismicity on the Moon"
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and the frequency matched predictions previously made.
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The experiment's sensor system was made of two parts:
61:
Dr. Gary Latham, Lamont-Doherty
Geological Observatory
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and may share similar origins from the Lunar Module.
138:. PSEP was the first seismometer to be deployed on a
350:"Apollo 11: Preliminary Science Report. NASA SP-214"
663:
33:The Passive Seismic Experiment Package on the Moon
602:
409:Latham, G; Ewing, M; Press, F; Sutton, G (1969).
771:
665:"Culture on the Moon: Bodies in Time and Space"
603:McGarr, A; Latham, G. V.; Gault, D. E. (1969).
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566:Geochimica et Cosmochimica Acta Supplement
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134:, physical nature, and composition of the
27:
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233:possible distance from the Lunar Module.
192:Apollo Lunar Surface Experiments Package
128:Early Apollo Surface Experiments Package
411:"The Apollo Passive Seismic Experiment"
78:Dr. George Sutton, University of Hawaii
75:, Massachusetts Institute of Technology
68:, Lamont-Doherty Geological Observatory
772:
741:
661:
562:"Apollo 11 passive seismic experiment"
300:
196:radioisotope thermoelectric generator
176:Lamont–Doherty Geological Observatory
93:Lamont-Doherty Geological Observatory
16:1969 American experiment on the Moon
742:Garber, Megan (December 19, 2012).
723:from the original on April 18, 2023
643:from the original on April 17, 2023
584:from the original on April 17, 2023
541:from the original on April 17, 2023
459:from the original on April 16, 2023
13:
754:from the original on April 9, 2022
744:"The trash we've left on the Moon"
377:from the original on April 4, 2023
156:California Institute of Technology
116:Passive Seismic Experiment Package
103:California Institute of Technology
22:Passive Seismic Experiment Package
14:
801:
710:
609:Journal of Geophysical Research
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1:
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511:10.1126/science.167.3918.455
487:"Passive Seismic Experiment"
435:10.1126/science.165.3890.241
297:had no identifiable origin.
7:
10:
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682:10.1007/s11759-015-9286-7
85:
54:
46:
38:
26:
357:NASA Special Publication
237:Measurements and science
213:Deployment and operation
105:Seismological Laboratory
790:Apollo program hardware
629:10.1029/JB074i025p05981
662:Gorman, Alice (2016).
276:life-support systems
621:1969JGR....74.5981M
578:1970GeCAS...1.2309L
503:1970Sci...167..455L
427:1969Sci...165..241L
369:1969NASSP.214......
363:. January 1, 1969.
98:Columbia University
47:Notable experiments
23:
301:Instrument failure
21:
615:(25): 5981–5994.
497:(3918): 455–457.
421:(3890): 241–250.
132:tectonic activity
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50:Apollo 11 mission
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180:Surveyor program
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126:as part of the
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5:
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676:(1): 110–128.
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271:Neil Armstrong
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140:planetary body
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670:Archaeologies
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572:: 2309–2320.
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66:Maurice Ewing
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756:. Retrieved
748:The Atlantic
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219:Lunar Module
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170:. All three
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86:Manufacturer
18:
142:other than
73:Frank Press
780:Seismology
774:Categories
309:References
252:moonquakes
186:Instrument
150:Background
785:Apollo 11
698:255375499
690:1555-8622
647:April 17,
637:129790741
588:April 17,
545:April 17,
519:0036-8075
463:April 16,
381:April 17,
124:Apollo 11
752:Archived
721:Archived
641:Archived
582:Archived
539:Archived
535:39004597
527:17781450
457:Archived
453:17814819
372:Archived
295:T-events
291:B-events
287:M-events
282:B-events
266:A-events
260:X-events
256:I-events
247:L-events
168:Ranger 5
164:Ranger 4
160:Ranger 3
55:Inventor
758:May 21,
727:May 21,
617:Bibcode
574:Bibcode
499:Bibcode
491:Science
423:Bibcode
415:Science
365:Bibcode
172:landers
39:Acronym
717:Forbes
696:
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694:S2CID
633:S2CID
531:S2CID
375:(PDF)
353:(PDF)
144:Earth
760:2023
729:2023
686:ISSN
649:2023
590:2023
547:2023
523:PMID
515:ISSN
465:2023
449:PMID
383:2023
258:and
166:and
154:The
136:Moon
120:PSEP
114:The
71:Dr.
64:Dr.
42:PSEP
678:doi
625:doi
507:doi
495:167
439:hdl
431:doi
419:165
361:214
221:at
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473:^
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118:(
Text is available under the Creative Commons Attribution-ShareAlike License. Additional terms may apply.
