System design and laboratory tests of an autonomous seismic station for space applications

We introduce a reference concept for a small and lightweight instrument carrier system for operation in isolated areas on Earth (or even on other celestial bodies) that autonomously records data after deployment at a site remote from the main station, thus called Remote Unit (RU). In particular, we present here concepts for realizing an autonomously operating seismometer, including support functions provided by encapsulating the actual instrument into the RU carrier. The conceptualization of the RU is based on the design of MASCOT, and intended for evolving into an instrument carrier for lunar exploration. Still in this paper we focus on the functionality needed for realizing the remote and autonomous aspects of the concept. Evolutionary steps needed for the system design to survive on a planetary body are briefly discussed, but not intensively covered in this paper, but elsewhere. We developed two prototypes of this RU including three seismic sensors each, either fixed, the other one with a built-in self-leveling mechanism. We used standard seismic sensors, which were integrated into a lightweight instrument carrier equipped with all required support structures for remote terrestrial operation, including power, thermal control, and data acquisition (total mass of prototypes not exceeding 3 kg and 10 kg, respectively). We have carried out laboratory tests and evaluated seismic data from these two types of RU to evaluate noise levels, spectral response, and overall performance of the systems. We demonstrate that the systems provide reproducible data at high signal levels, which warrant comfortable scientific interpretation of seismic data from active and passive experiments. Noise level and detected spectral anomalies (due to mechanical structure and associated Eigenfrequencies) are well within expectations.