Simon Christian Stähler

SUMMARY: X. Huang et al. reported the detection of 67 teleseismic marsquakes identified by P- and S-wave arrivals. The authors used a deep learning phase picker trained on local earthquake data and applied it to narrow-bandpass filtered seismic data recorded by NASA’s InSight seismometer, making use of similarities between local earthquake and teleiseismic marsquake recordings when adjusting for sampling rate and S-P timescaling relations. We review all detections as similarly done for the Marsquake Service catalogue and other studies on this data set, using the complementary wind and pressure data recorded by InSight. As these auxiliary data were not recorded in the second half of the mission, we also infer wind contamination from bandwidths in the seismic data that contain wind-sensitive lander modes. Additionally, we analyse the signal polarization to compare it with the expected characteristics of P and S waves and the background noise. Our review indicates that all 67 detections reported by the authors correspond to atmospheric noise. In most cases, the detections relate to the seismic signature of small wind bursts followed by larger wind bursts, onsets of which are interpreted as P and S waves by the authors. Further, we show that if these events were interpreted as genuine marsquakes, their inferred epicentral distance distribution would not match typical marsquake distances, while their magnitudes would make them the largest events of the catalogue. For future studies that deal with seismic event detection and interpretation from InSight, we recommend a careful consideration of the established event and noise signal markers described in this comment and in the literature to avoid misinterpretation of noise as event signals.

LunarLeaper is a robotic mission concept aimed at advancing our understanding of the Moon’s subsurface structure and geological evolution through the exploration of volcanic pits—steep-walled collapse features on the lunar surface. Orbital observations indicate that some of these pits may provide access to extensive subsurface lava tube systems. However, such interpretations are limited by spatial resolution and viewing geometry, and only an in-situ surface mission can unambiguously confirm and characterize the relationship between pits and underlying caves. We propose the use of a legged robotic platform to deploy geophysical instrumentation to the rim of a lunar pit on the near side of the Moon. From this vantage point, the mission will confirm the presence of a lava tube, constrain its geometry, and employ imaging and spectrometric measurements to reconstruct the volcanic history of the pit and its surrounding terrain.The baseline payload for LunarLeaper consists of a camera system, a ground-penetrating radar, a gravimeter, and a spectrometer. We report the current status of payload accommodation on the robotic platform:The camera requirements for the mission can be met by an COTS camera system previously used as engineering cameras for ESA spacecraft, such as BepiColombo.We have developed a compact, PCB-based antenna system for the ground-penetrating radar that can be fully integrated beneath the robot body.Forward modelling of the expected gravimetric signal, combined with a preliminary noise budget that accounts for instrument tilt, shows that the sensitivity of the HERA-heritage gravimeter exceeds mission requirements by approximately an order of magnitude.Measurements with the Fabry-Perot spectrometer have been demonstrated against several mineralogical compositions.A preliminary concept of operations demonstrates that payload operation and data acquisition are compatible with overall mission constraints, specifically the mission duration of less than one lunar day.Together, these results demonstrate that the combined geophysical and imaging payload suite can be accommodated on a small robotic platform, as currently being developed by the Robotic Systems Lab at ETH Zürich.

NASA's InSight mission has provided an unprecedented snapshot of Mars' seismicity, despite data analysis challenges arising from low signal‐to‐noise ratios (SNR) and single‐station constraints. High frequency (HF) events—the most common type—were initially assumed to propagate through shallow crustal layers. However, several impacts that occurred late in the mission provided independent distance constraints, indicating that HF event energy must have propagated through the mantle. We analyzed the full HF data set using an extended catalog and denoised waveforms derived with deep learning (DL) techniques. Using a DL ensemble, we picked phase arrivals on denoised envelopes and estimated SNR‐dependent pick timing uncertainties based on the removed noise. We computed distances consistent with mantle paths using the latest Mars interior models, while the back azimuth remained inconclusive due to local resonance dominating the HF bandwidth. We compared and grouped HF recordings by their similarity and investigated how attenuation properties shape their envelopes. Additionally, we re‐calibrated and assigned magnitudes for the extended catalog. Overall, we (re‐)located 1,430 HF events clustered between epicentral distances of around 1,600–3,600 km, but without constraints on the back azimuth, their source region remains speculative. Based on spatiotemporal similarities, we attributed a subset of 1,357 events to a common source region and labeled them as swarm events. The analysis of envelope shape confirms and extends previous results of stratified attenuation properties. Swarm events, with magnitudes between 1.5 and 2.5, are cumulatively equivalent to a single magnitude 4 event and show a high ‐value and clear seasonal trends in seismicity.

LunarLeaper is a mission concept designed to robotically explore subsurface lava tubes on the Moon. Lunar pits, steep-walled collapse features, are thought to be connected to such lava tube systems and more than 300 have been identified through remote sensing. These natural subsurface structures hold immense value for exploration and scientific investigations, because they offer protection from radiation, micrometeorites, and harsh temperature fluctuations on the lunr surface and as such, they have been proposed for possible future human habitation. In addition, the extent, nature and duration of lunar volcanism is poorly understood and the uniquely exposed stratigraphy along the pit walls might hold crucial information on the volcanic history if the Moon. However, current orbital imaging lacks sufficient resolution to confirm these connections, making ground-truth exploration essential. LunarLeaper aims to address these knowledge gaps by deploying a lightweight (

The InSight lander represents a unique opportunity to correlate seismic data with impact events identified in orbital images, enabling the characterization of the physical properties of the martian crust and mantle. Here, we present the first comprehensive catalog of impacts that occurred during the InSight mission within a 50° radius around the lander. We use a machine learning‐enabled approach to identify 123 date‐constrained impacts with diameters between ∼1 and 22.5 m. We estimate an impact rate of 2.7 × 10 ⁻⁶ /km ² /year for >3.9 m effective diameter, which is ∼1.6–∼2.5 times higher than previously derived for Mars. We identify 49 seismic events with one or several potential impact match(es) including a 21.5 m crater located near Cerberus Fossae. Our catalog will enable a more accurate characterization of the propagation of seismic body waves at intermediate distances to InSight (5–50°), with major implications for estimates of other seismic event distances.

With the selection of multiple missions to Venus by NASA and ESA that are planned to launch in the coming decade, we will greatly improve our understanding of Venus. However, none of these missions have determining the seismicity of the planet as one of their primary objectives. Nevertheless, constraints on the seismicity remain crucial to understand the tectonic activity and geodynamic regime of the planet and its interior structure. Funded by the International Space Science Institute (ISSI) in Bern, Switzerland, we have gathered an interdisciplinary team of experts in seismology, geology, and geodynamics to assess the potential seismicity of Venus, specific regions that could be seismically active at present, and the methods to detect them.Here, we present the findings from our second ISSI team meeting (January 29 - February 2, 2024), aiming to review knowledge on Venus's seismicity and interior and identify the best approaches for future missions. We present the feasibility, advantages, and disadvantages of different seismic observation techniques on the surface (e.g., broadband seismometers, distributed acoustic sensing methods), from a balloon (acoustic sensors), and from orbit (airglow imagers). We make a recommendation for the instrumentation of a future seismology-focused mission to Venus. We also suggest target regions with a high likelihood of significant surface deformation and/or seismicity. These targets are useful for the upcoming VERITAS (Venus Emissivity, Radio Science, InSAR, Topography and Spectroscopy) and EnVision missions and would specifically benefit from the repeat pass interferometry of VERITAS, which detects surface deformation and can therefore in principle constrain the maximum displacement of surface faulting at locations that are visited twice during the mission.

Understanding the elastic properties of Earth's inner core is crucial for unraveling its role in the planet’s evolution and dynamics. Seismic shear waves provide a direct means to constrain the shear modulus of the solid inner core at high frequencies. However, their detection has been challenging due to their extremely weak amplitude and interference from other seismic arrivals (Doornbos, 1974). This study aims to provide direct observations of inner-core shear waves through a systematic search using the AlpArray Seismic Network (AASN), a large European seismic array. The approach combines 3-C polarization filtering and slant-stacking techniques. The inspection focuses on events between 2015 and early 2022 within the epicentral distance range of ~110-150° from the AASN. This source-receiver geometry is close to that of previous PKJKP observation reported using the Gräfenberg array (Cao et al., 2005).Our systematic search and classification reveal multiple potential observations of PKJKP at frequencies > 0.1 Hz, consistent in both time and slowness with the 1-D Earth model ak135, as well as previous body-wave-based observations, particularly Wookey and Helffrich (2008). The new evidence of PKJKP demonstrates a path forward for formalizing a method for the repeatable detection of inner-core shear waves for different source-receiver geometries. Additional PKJKP observations and comprehensive modeling are essential for gaining insights into the intricate inner-core structure and phenomena, such as anisotropy and focusing effects, which could explain the limited number of observations to date.

We present LunarLeaper, a robotic explorer concept in response to the ESA 2023 Small Missions call. Pits, volcanic collapse features with near-vertical walls, have been identified across the lunar and Martian surface. These pits are high priority exploration destinations because some, referred to as skylights, might provide access to subsurface lava tube systems. Lava tubes are of particular interest for future human exploration as they offer protection from harmful radiation, micrometeorites and provide temperate and more stable thermal environments compared to the lunar surface. We propose to use a small legged robot (ETH SpaceHopper,