Active Source Seismology from Anthropogenic1 1 Sources2 During3 the4 Apollo 11 Lunar Mission A. S. Khatib , N. C. Schmerr , B. Feist , J. B. Plescia , N. E. Petro 1
[email protected], University of Maryland, College Park MD, 2 NASA Johnson Space Center, Houston TX, 3 Johns Hopkins University Applied Physics Laboratory, Baltimore MD, 4 NASA Goddard Space Flight Center, Greenbelt MD I. Introduction III. Spatial array V. Time correction The Passive Seismic Experiment Package (PSEP) deployed by The time-stamps on the seismic signal were generated upon the Apollo 11 astronauts Neil Armstrong and Buzz Aldrin during reception of the signal at base stations; seismic event times must their extravehicular activity (EVA) on July 21st, 1969 provided the take into account the radio wave travel time between generation first seismic data from another body in the Solar System [1,2]. The at Tranquility Base and the nearest receiving base station on Earth. primary sources of seismicity in the Apollo 11 seismic data were The travel times are calculated and subtracted from the event times. the movements and activities of the astronauts, ascent of the The time-stamps on the audio signal were generated upon Lunar Module (LM), and thermoelastic and volatile venting from reception of the signal at Mission Control in Houston; audio event the LM descent module. times must take into account the radio wave travel time between Here we use the anthropogenic sources of seismic signal from generation at Tranquility Base and the nearest receiving base station the movements of the astronauts on the surface to perform an on Earth, and the travel time between the base station and Houston.