T he Interior Exploration using Seismic Investigations, Geodesy and Heat Transport (InSight) mission landed on Mars on 26 November 2018 in Elysium Planitia 1,2 , 38 years after the end of Viking 2 lander operations. At the time, Viking's seismometer 3 did not succeed in making any convincing Marsquake detections, due to its on-deck installation and high wind sensitivity. InSight therefore provides the first direct geophysical in situ investigations of Mars's interior structure by seismology 1,4. The Seismic Experiment for Interior Structure (SEIS) 5 monitors the ground acceleration with six axes: three Very Broad Band (VBB) oblique axes, sensitive to frequencies from tidal up to 10 Hz, and one vertical and two horizontal Short Period (SP) axes, covering frequencies from ~0.1 Hz to 50 Hz. SEIS is complemented by the APSS experiment 6 (InSight Auxiliary Payload Sensor Suite), which includes pressure and TWINS (Temperature and Winds for InSight) sensors and a magnetometer. These sensors monitor the atmospheric sources of seismic noise and signals 7. After seven sols (Martian days) of SP on-deck operation, with seismic noise comparable to that of Viking 3 , InSight's robotic arm 8 placed SEIS on the ground 22 sols after landing, at a location selected through analysis of InSight's imaging data 9. After levelling and noise assessment, the Wind and Thermal Shield was deployed on sol 66 (2 February 2019). A few days later, all six axes started continuous seismic recording, at 20 samples per second (sps) for VBBs and 100 sps for SPs. After onboard decimation, continuous records at rates from 2 to 20 sps and event records 5 at 100 sps are transmitted. Several layers of thermal protection and very low self-noise enable the SEIS VBB sensors to record the daily variation of the

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The InSight (Interior Exploration using Seismic Investigations, Geodesy and Heat Transport) mission landed on the surface of Mars on November 26, 2018. One of the scientific instruments in the payload that is essential to the mission is the SEIS package (Seismic Experiment for Interior Structure) which includes a very broadband and a short period seismometer. More than one year since the landing, SEIS continues to be fully operational and has been collecting an exceptional data set which contains not only the signals of seismic origins, but also noise and artifacts induced by the martian environment, the hardware on the ground that includes the seismic sensors, and the programmed operational activities of the lander . Many of these non-seismic signals will be unfamiliar to the scientific community. In addition, many of these signals have signatures that may resemble seismic events either or both in time and frequency domains. Here, we report our observations of common non-seismic signals as seen during the first 478 sols of the SEIS data, i.e. from landing till the end of March 2020. This manuscript is intended to provide a guide to scientists who use the data recorded on SEIS, detailing the general attributes of the most commonly observed non-seismic features. It will help to clarify the characteristics of the seismic dataset for future research, and to avoid misinterpretations when searching for events.

The Seismic Experiment for Interior Structures (SEIS) was deployed on Mars in November 2018 and began science operations in March 2019. SEIS is the primary instrument of the Interior Exploration using Seismic Investigations, Geodesy and Heat Transport (InSight) mission, which was launched by the National Aeronautics and Space Administration (NASA). The acquisition and control (AC) electronics is a key element of SEIS. The AC acquires the seismic signals of the two sets of seismic sensors with high resolution, stores the data in its local nonvolatile memory for later transmission by the lander, and controls the numerous functions of SEIS. In this article, we present an overview of the AC with its connections to the sensors and to the lander, as well as its functionality. We describe the elements of the acquisition chains and filters, and discuss the performance of the seismic and temperature channels. Furthermore, we outline the safety functions and health monitoring, which are of paramount importance for reliable operation on Mars. In addition, we analyze an artefact affecting the seismic data referred to as the “tick-noise” and provide a method to remove this artefact by post-processing the data.

Hammering of the InSight heat probe generates high-frequency seismic signals that exceed the Nyquist frequency of the seismometer.• We developed a new data acquisition and reconstruction workflow that allows for the recovery of the full-bandwidth hammering signals.• During hammering, we deliberately turned off the seismometer's anti-aliasing filters and reconstructed the aliased signal using a sparseneess-promoting algorithm.

Interior exploration using Seismic Investigations, Geodesy and Heat Transport's (InSight) seismometer package Seismic Experiment for Interior Structure (SEIS) was placed on the surface of Mars at about 1.2 m distance from the thermal properties instrument Heat flow and Physical Properties Package (HP3) that includes a self‐hammering probe. Recording the hammering noise with SEIS provided a unique opportunity to estimate the seismic wave velocities of the shallow regolith at the landing site. However, the value of studying the seismic signals of the hammering was only realized after critical hardware decisions were already taken. Furthermore, the design and nominal operation of both SEIS and HP3 are nonideal for such high‐resolution seismic measurements. Therefore, a series of adaptations had to be implemented to operate the self‐hammering probe as a controlled seismic source and SEIS as a high‐frequency seismic receiver including the design of a high‐precision timing and an innovative high‐frequency sampling workflow. By interpreting the first‐arriving seismic waves as a P‐wave and identifying first‐arriving S‐waves by polarization analysis, we determined effective P‐ and S‐wave velocities of vP=119−21+45 ${v}_{P}=11{9}_{-21}^{+45}$ m/s and vS=63−7+11 ${v}_{S}=6{3}_{-7}^{+11}$ m/s, respectively, from around 2,000 hammer stroke recordings. These velocities likely represent bulk estimates for the uppermost several 10s of cm of regolith. An analysis of the P‐wave incidence angles provided an independent vP/vS ratio estimate of 1.84−0.35+0.89 $1.8{4}_{-0.35}^{+0.89}$ that compares well with the traveltime based estimate of 1.86−0.25+0.42 $1.8{6}_{-0.25}^{+0.42}$. The low seismic velocities are consistent with those observed for low‐density unconsolidated sands and are in agreement with estimates obtained by other methods.

The NASA InSight (Interior exploration using Seismic Investigations, Geodesy and Heat Transport) lander touched down at Elysium Planitia on Mars in November 2018. The main goal of the mission is to investigate the internal structure of Mars using seismic, geothermal, and radio science experiments (Banerdt et al., 2020). Two scientific instruments were deployed on the surface of Mars (Figure 1a): (a) The Seismic Experiment for Interior Structure (SEIS) package (Lognonné et al., 2019) that consists of two three-component seismometers to monitor the Martian seismicity (e.g., Clinton et al., 2021;Giardini et al., 2020) and to image the interior of the planet (e.g.,

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