Urban seismic noise investigation at the site of ESA/DLR’s future LUNA facility at Cologne, Germany

Kurzfassung

As international efforts to return humans to the Moon are increasing, ESA's European Astronaut Center (EAC) and the German Aerospace Center (DLR) are expanding their facilities by the LUNA habitat providing a 700m²-wide testbed covered by 60cm lunar regolith simulant (EAC-1) for astronaut training, including deploying and operating geological and seismic regolith characterization experiments, In Site Resource Utilization technologies (ISRU), biological and chemical experiments by both telerobotic and human activity. The LUNA facility will be operated as collaboration between ESA and DLR's Microgravity User Support Center (MUSC, see also the presentation by Knapmeyer et al. at this conference). Geophysical experiments have proven useful to investigate the subsurface structure at the landing sites of e.g. Apollo and Chang'e missions on the Moon, but also at the InSight landing site on Mars, and a seismometer experiment to the lunar far side is already scheduled (Far Side Seismic suite, in 2025). To support future geophysical investigations on the Moon, a first seismic experiment was conducted in June, 2018 at the previously envisioned site of the LUNA facility between the :envihab, a research facility of the Institute for Aerospace Medicine and the European Astronaut Center (EAC) at Cologne-Porz. This passive seismic experiment consisted of a four-element, Y-shaped array of short period seismometers, based on the layout of the Apollo 17 seismic experiment. It recorded regional seismicity as well as urban noise. These measurements will be repeated and expanded by an active seismic refraction experiment at the new construction site just south of the EAC - before, during and after the construction of the facility, before and after the installment of the regolith cover to investigate the impact of the LUNA facility on the data quality and coupling to the ground. We present details of the 2018 experiment as well as preliminary results, analyzing ambient noise to map the dominant sources of urban noise such as car traffic and airplane traffic at the nearby CGN international airport, the operational noises of the :envihab centrifuge and the wind tunnel as well as nearby construction and drilling.