A New Archive of Apollo’s Lunar Seismic Data

Abstract

The Apollo astronauts deployed seismic experiments on the nearside of the Moon between 1969 and 1972. Five stations collected passive seismic data. Apollo 11 operated for around 20 days, and stations 12, 14, 15, and 16 operated nearly continuously from their installation until 1977. Seismic data were collected and digitized on the Moon and transmitted to Earth. The data were recorded on magnetic reel-to-reel tapes, with timestamps representing the signal reception time on Earth. The taped data have been widely used for many applications and have previously been shared in various formats. The data have slightly varying sampling rates, due to random fluctuations of the data sampler and also its sensitivity to the significant temperature variations on the Moon’s surface. Additionally, there were timing errors. Previously shared versions of the Apollo data were affected by these problems. We have reimported the passive data to SEED (Standard for the Exchange of Earthquake Data) format, and we make these data available via Incorporated Research Institutions for Seismology and the Planetary Data System. We have cleaned the timestamp series to reduce incorrectly recorded timestamps. The archive includes five tracks: three components of the mid-period seismometers, one short-period component, and a time track containing the timestamps. The seismic data are provided unprocessed in their raw format, and we provide instrument response files. We hope that the new archive will make it easier for a new generation of seismologists to use these data to learn more about the structure of the Moon.