Ocean processes in the Southwest North Atlantic (SWNA) play an important role in long-term earth and ocean climate change. This region is also a resource-rich coastal zone with abundant fisheries and other material assets. Combined, the previously released NCEI Northwest Atlantic (NWA) regional climatology (RC) and newly developed SWNA RC provide complete coverage of the Gulf Stream system, which is the critical element of northward heat transport and the Atlantic Meridional Overturning Circulation. The SWNA RC is a collection of high-resolution quality-controlled temperature and salinity fields on standard depth levels from the sea surface to 4,900 m depth. This RC is based on temperature and salinity observations from the 2018 release of the World Ocean Database. The coverage includes the years 1955 to 2017 by annual, seasonal, and monthly fields for the entire period, as well as for each of the six decades. All fields computed on three horizontal grids: 1°x1°, 1/4°x1/4°, and 1/10°x1/10° degree. The SWNA RC is instrumental for assessing ocean climate changes in this region of the North Atlantic Ocean over the 1955-2017 time period and can be used in various climate studies, environmental research projects, and related applications.

Wheat is one of the most widely grown crops and it plays an important role in food production. Currently there is considerable interest in identifying traits that contribute to high yields. Trait selection has mainly focused on the above-ground part of the plant neglecting below-ground processes. Climate change and the greater uncertainty in weather conditions challenge our current food system and create the need to select more varieties with grater resilience against the effects of climate variation. The root system of the plant plays a key part in this resilience, but it is difficult to study at the field-scale which is essential for the effective selection of breeding lines. Geophysical tools such as electromagnetic induction (EMI) and electrical resistivity tomography (ERT) offer the possibility to study the below-ground phenotype of the plant in a non-destructive and high-throughput manner. In this study, changes in soil moisture induced by root water uptake are monitored using time-lapse ERT/EMI surveys. These methods were applied at two scales: (a) at a high-spatial resolution where hundreds of wheat varieties were monitored monthly using EMI in a wheat breeding field trial and (b) at high-temporal resolution where hourly ERT measurements were collected along with above-ground phenotyping traits on a few plots with a field facility (Field Scanalyzer). Coupling these geophysically-based below-ground data with above-ground canopy measurements can increase our understanding of the crop response to its environment. Good correlation was found between leaf area index (LAI) and soil drying inferred from EMI measurements for the high-spatial experiment (a). The ERT monitoring experiment (b) accurately showed the dynamics of two different nitrogen treatments, their interactions with weather conditions and their correlation with above-ground crop growth. Coupling geophysically-based below-ground measurements with above-ground data allows the increased understanding of the whole plant phenotype. This might help to identify useful traits to select for increased crop yield and resilience.

The Lattice Boltzmann Method (LBM) is an elegant method to simulate fluid dynamics based on modelling distributions of particles moving and colliding on a lattice. We present examples of two phase flow using the Rothman and Keller (RK) colour gradient Lattice Boltzmann model to study phenomena associated with two phase immiscible fluid flow relevant to water being injected into an oil saturated sandstone. The model involves streaming and colliding two distribution functions (red and blue) representing the number densities of two fluids, where the collision step involves two terms which represents how particle distributions change in each time step due to collision while encouraging colour segregation. We conducted 2D numerical experiments to study the effect of wetting angle on the morphology of flow of a lower viscosity fluid being injected at the left of a simplified model rock matrix that was filled with a higher viscosity fluid. The cases studied involved the injected fluid being non-wetting (wetting angle = 180 degrees), neutral wetting (wetting angle = 90 degrees) and wetting (wetting angle = 0 degrees). These three cases show viscous fingering behaviour with different morphologies for the different wetting angles. For the case of the non-wetting fluid injection, a series of narrow fingers are observed. For the case of neutral wetting, broader and rounded fingers are observed. And for the case of injecting a wetting fluid, a broad but distorted front is observed approaching stable displacement. The results show the importance of the wetting angle on the morphology of viscous fingering. This study demonstrates that the multiphase Lattice Boltzmann Method can simulate phenomenology relevant to studies of enhanced oil recovery such as water injection, and hence, may lead to improved estimates of oil recovery factors.

The upper atmosphere of Mars is directly affected by solar activity and the resulting solar irradiance impinging upon it. Variations in solar forcing can affect the rate at which atmospheric species escape from the planetary system. Remotely sensed observations of the upper atmosphere of Mars have been made during solar activity extrema of Solar Cycles 22 and 24. These observations were made of D and H Lyman-a emissions using the Mars Atmosphere and Volatile Evolution (MAVEN) mission and the Hubble Space Telescope (HST) high resolution spectrographs. Data obtained from the two missions are analyzed and used to derive densities and escape rates of D and H from the martian upper atmosphere. The results show that the properties of these two water-spawned atoms vary with solar cycle, and display significant inter-annual variability, mainly due to variations in atmospheric temperature. The findings suggest that cooler atmospheric temperatures due to reduced solar EUV flux may enhance the abundance of H atoms in the upper atmosphere of Mars, yet this does not increase their escape rates.

Probably the founding father of Geology, Sir James Hutton was raised as a doctor but his passions for the nature surrounding his farm led him to rocks, then specimens, then fossils. The result was what we might call a comparative physician – the first paleontologist, in fact. His upbringing in medicine had given him the classical knowledge of his time, from Latin to mathematics, and from biology to drawing. Not only did the lack of a specific scientific discipline bring Sir Hutton to devise a novel field of study of his own – it also molded strands of his formal learning into a synthesis of intellectual tools. These days, hyper specialization has brought upon novel discoveries of paramount importance and marvel, from graphene to vaccines. It also is a means of necessity in applying for academic positions and to publish in ever nascent journals. This architecture, however, reflects a system of parallel disciplinarity, with scientific fields somehow on their own course. On the other hand, complexities at stake require solutions that may well evade any given single field, at times astray from usual avenues. Such approach not only entails multi-disciplinarity (diverse teams – yesterday), but it also requires cross-disciplinarity (across specific disciplines – today) and, especially, trans-disciplinarity (beyond firm disciplines – today and tomorrow). For their very nature, geosciences are bound to glean lessons learned from the past to provide insight into the future. Geoscientists were once thought to study ancient rocks, fiddle with very slow-moving tectonic plates, and bantering about invisible earth’s features, too large, or too deep, or too far away to even imagine for us earthlings. But the geosciences are more than ever side by side with some of the most pressing issues surrounding contemporary societies – after having been at the heart of a couple of global energy revolutions. From a series of examples, this work thus tries to put into perspective: Hazards stemming from multiple, at times unpredictable sources; The precious role of geosciences to decipher them – and to forecast them; The complexity of natural hazards, the (need of) flexibility in human planning; Modern issues challenging societies and economies – today, tomorrow, and thereafter.

The formation of layers at mid-latitudes has been related to neutral winds activity at altitudes below 130km in the Mesosphere and Lower Thermosphere (MLT). Recent SAMI3 simulations by Krall et al. (2020) of ionospheric metallic layers at Arecibo suggest that forces induced by the meridional winds cause low altitude layers near 100 km. However, the classic mechanism, originally proposed by Whitehead (1961), correctly states that zonal wind shear has a bigger effect than meridional wind shear in the lower E region. Haldoupis and Shalimov (2021), referring to observations of ionosonde-based sporadic E statistics and radio occultation sporadic E measurements using low Earth orbiting satellites, support the idea that zonal winds dominate layer formation at these altitudes, apparently disputing the findings of Krall et al. (2020). Perhaps the latest technique to continuously measure mid-latitude MLT daytime neutral winds was developed by Hysell et al. (2014). That technique used a unique configuration of the Arecibo radar dual-beam. Unfortunately, since Arecibo lost the capability of the dual-beam in 2017 (when one antenna was destroyed by Hurricane Maria), there are only few valuable data sets that can help elucidate the origin of the lower altitude layers at Arecibo. We present Arecibo neutral wind data correlated with lower altitude layers. While not disputing current theory, we find that, near 100 km, meridional neutral wind shear can be much stronger than zonal wind shear when a layer is present, with the meridional shear correctly positioned to support the layer. We also present a complete analysis of the vertical ion drift, including declination, where the meridional winds become more important and with a reversed mechanism for altitudes below 115km for Arecibo conditions. References: Haldoupis et al. (2021), https://doi.org/10.1016/j.jastp.2021.105537 Hysell et al. (2014), http://doi.org/10.1002/2013JA019621 Krall et al. (2020), https://doi.org/10.1029/2019JA027297

During the forthcoming decade and beyond there will be a plethora of global space-based active and passive measurements of cirrus and ice cloud. These measurements will be across the electromagnetic spectrum, from the ultra-violet to the far-infrared, through to the sub-millimeter, where there are no current radiance observations in the latter spectral regions. To take advantage of these unprecedented high-resolution and spectral-like measurements, ice crystal models are required that are physically consistent throughout the electromagnetic spectrum, and which are consistent with microphysics assumptions in weather and climate models. Achieving such physical consistency between ice crystal models, remote-sensing, and large-scale models to meet the challenges posed by the forthcoming measurements over the next decade or so is problematic. However, it is necessary to overcome this difficulty to improve the predictive quality of weather and climate models to address extreme weather events and climate change, respectively. However, cirrus and ice cloud types consist of ice crystals that vary considerably both in shape and size between the cloud top and bottom. Not surprisingly, with such variability in the shapes and sizes, obtaining models that are coherent across the spectrum while at the same time being consistent with microphysics assumptions in weather and climate models is difficult. In this talk, to address the above issues, an approach using an ensemble model of cirrus ice crystals to predict consistently the observed radiative properties of cirrus from the ultra-violet to the far-infrared will be discussed using aircraft and satellite-based high-resolution radiance measurements. In this analysis, different shapes of the particle size distribution are utilized that are consistent with a weather and climate model, remote-sensing, and with an in-situ mass power law. Here, the need for improved simultaneous in-situ and aircraft remote-sensing spectral characterization of cirrus across the electromagnetic spectrum will be emphasized. Moreover, an example of the development of a new ice crystal model that follows in-situ ice crystal mass and area power laws, which are consistent with a weather and climate model is described, with some preliminary results, to help address the radiative issues.

Coastal stratocumulus clouds (Sc) have unique modeling challenges due to their development over coastal land, one of them being the accurate representation of surface fluxes. Unlike marine Sc, where the ocean can store significant heat and release relatively constant surface heat fluxes over the day, there are strong diurnal variations of both sensible and latent heat fluxes over land. Moreover, land surface fluxes have a strong feedback with cloud cover. Many modeling efforts have been directed to improve the representation of surface fluxes through developing more accurate land surface models with increasing complexity. Regarding the boundary layer turbulence, for marine Sc, greater sensible fluxes are known to intensify updrafts and increase entrainment, while greater latent heat fluxes have been linked to decoupling. An example of surface flux variations for Marine Sc is the transition of Sc to shallow Cumulus along the trade winds, which occurs over a number of days. For coastal land, changes of surface fluxes occur in a much shorter timescale (hours), and the sensitivity of their dynamical response has not been explored. In this work, we study the response of coastal Sc to controlled variations of surface fluxes using Large Eddy Simulations. Representative scenarios of diurnal profiles are generated using 12 years of surface flux measurements for cloudy days over southern California, and then simulated under several configurations that describe sudden and gradual changes of surface fluxes with varied timing and magnitude. Sudden changes result in increased cloud thinning and earlier dissipation times, although the timing of the sudden increase is also important, in relation to the original dissipation time. The response time to sudden changes of surface fluxes is evident in the evolution of maximum vertical velocity and vertically integrated Turbulent Kinetic Energy, with timescales of 1 and 2 eddy turnover times, respectively.

Apparently stable central Indian craton has been experiencing a number of micro-seismicity in and around the pristine Son-Narmada-South fault (SNSF), possibly because of creep along some reactivated or unidentified fracture planes. Drainage network being highly susceptible to even subtle active tectonics, a reconnaissance study of the area has been carried out using river morphometric analysis. Thereafter, a Principal Scattering Interferometry time series (PSInSAR-TS) analysis (Hooper et al 2004, 2007) was performed to precisely locate the surface-tip of the slip plane. And finally, the fracture geometry and orientation of the slip vector was enumerated by integrating PSINSAR with morphometric analysis. Generally, drainages respond to block uplift with abrupt incision and thereby making a very narrow channel width. However, delineating such incision from the standard Width-Depth ratio from DEM based studies becomes difficult, because of its coarser resolution. Therefore, considering rectangular channel flow for a stable river, the expected width was compared with the actual width of the river measured from high resolution Sentinel II images following the relation modified after Finnegan et al., 2005; which states that W =KA^(2/3)S^(-3/16), where the constant K depends on the rectangular channel geometry, manning constant and rainfall in the area, A is upper catchment area and S is slope of the river reaches. A NE-SW trending zone of narrower channel width was identified with this procedure which was interpreted as a result of block uplift, later confirmed from the rate of uplift preliminarily calculated using an expression derived from basic stream-power equation: U=K(((Z(a)-Z(o))/Χ)^n) (A^m), where the uplift (U) is a function of erodibility (K), river catchment area (A) and chi (χ) value as per Perron and Royden 2012. PSInSAR-TS analysis of the area delineated an average net-slip rate of 11mm/year along a number of NE-SW trending south dipping oblique slip reverse faults, with sinistral strike slip components, arranged in enechelon pattern and are softly linked to each other with jogs accommodating movements in normal sense. Lastly, the fault geometry was confirmed by comparing the deformation map generated from the InSAR technique with the field evidence and previous studies.

The Orbiting Carbon Observatories-2 and 3 make space-based measurements in the oxygen A-band and the weak and strong carbon dioxide (CO2) bands. A Bayesian optimal estimation approach is employed to retrieve the column averaged CO2 dry air mole fraction from these measurements. This retrieval requires a large number of polarized, multiple-scattering radiative transfer (RT) calculations for each iteration. These RT calculations take up the majority of the processing time for each retrieval, and slow down the algorithm to the point that reprocessing data from the mission over multiple years becomes very expensive. To accelerate the RT calculations and thereby ease this bottleneck, we have developed a novel approach that enables reproduction of the spectra for the three OCO-2/3 instrument bands from radiances calculated at a small subset of monochromatic wavelengths. This allows reduction of the number of monochromatic RT calculations by a factor of 20 and can be achieved with radiance errors of less than 0.1% with respect to the existing algorithm. The technique is applicable to similar retrieval algorithms for other greenhouse gas sensors with large data volumes, such as GeoCarb, GOSAT-3, and CO2M.

The Arecibo Observatory (AO) could modify the ionosphere using high frequency (HF) waves. During the HF experiments, the incoherent scatter radar (ISR) was used to study the behavior of the ion, plasma, and gyro lines with 150m height resolution. One year ago, the AO platform collapsed and put a pause for new experiments. However, the archived ISR data can answer open questions like the electron heating evolution in the interaction region. This paper presents a new methodology to estimate the electron temperature (Te) at the resonance altitude based on the physics of the HF wave-plasma interaction. Estimating Te inside regions where the ionospheric plasma interacts with the powerful HF ground waves is a challenge. Standard ISR techniques to assess the temperatures using the ion line are based on Maxwellian approximations. However, the irregularities generated by HF experiments induce non-Maxwellian behaviors. Therefore, a new approach is proposed using the ion-acoustic phase velocity (C_ia) of the ion-acoustic waves generated during the HF experiments. The ion acoustic velocity can be derived from the ISR enhanced plasma line (HFPL) produced during active experiments. The HFPL is mainly attributed to the HF wave decaying into a cascade of Langmuir and ion-acoustic waves, known as Parametric Decay Instability (PDI). The ion-acoustic waves travel at speed: C_ia=λf_ia, where f_ia is the ion-acoustic frequency, and λ is the radar (Bragg backscatter) wavelength. The PDI signature is characterized at the HFPL by cascaded lines spaced in frequency by multiples of f_ia. After measuring f_ia, Te is obtained using f_ia=1/λ √(k_B (Te+2Ti)/m_i), where Ti and mi are the ion temperature and mass. Estimates for one particular experiment on June 12, 2019 show that Te is usually higher at the top of the layer and the beginning of every HF pulse. For example, at 280s after 16:43:00LT, it reached a value near 3500 K, when the temperature outside of the interaction region was below 1600 K.

Ocean governance is characterised by social-ecological complexity and divergence in stakeholder values and perspectives. Meeting the challenges set out in the UN Decade of Ocean Science for Sustainable Development will require transdisciplinary approaches that can embrace multiple ways of knowing to develop shared understandings within interdependent communities of practice and ensure they can be applied in interventions that are adaptive, proactive, socially just, critically reflexive and fit to meet the Decade’s challenges. We present the outcomes of an innovative participatory art process, the Exquisite Corpse Project, with the aim of highlighting multiple perspectives, and developing empathy between participants. We will engage a selected group of researchers from the emerging ‘Ocean Art-Ocean Science’ community to explore the topic of marine heatwaves and their impacts based on data collected in the Northeast Pacific by Ocean Networks Canada and other sources. Through a facilitated process, participants will create three pieces of art that will build on each other and will be exchanged between participants. At the end, all created artworks will be reviewed by the full group to explore emerging insights on marine heatwaves and to surface participants’ underlying values and emotions, which is rarely done in scientific circles where the main mode of discourse employs rational dispassionate exchange. By creating a fun, emotionally-engaging process, we aim to show how the Exquisite Corpse project can strengthen interpersonal bonds, build social cohesion, create opportunities to surface people’s values and perspectives, and develop new transdisciplinary insights in a non-confrontational way. This study is part of an ongoing process exploring transdisciplinary approaches for multidirectional art-science collaborations and developing new research methods for including artistic insight and expression within the scientific discovery process. Instead of the conventional ‘outward looking’ strategy of many art-science projects translating scientific outputs to new formats, our approach is primarily ‘inward looking’. We aim to provide an opportunity for scientists to create art, thus allowing them to explore their own emotions, values and experiences through different ways of knowing.

Application of fixed timestep numerical schemes in engineering has long been criticized for their inaccuracy, inefficiency, and inconsistency across time-scales. Yet, to date, most hydrological models fix their timestep to the input rainfall resolution, instead of using adaptive schemes. Aside from their known maladies, we argue that fixed timestep schemes also suffer from ‘commensurability’ errors: errors that emerge when comparing quantities that are not precisely at the same spatial/temporal scales. At least at <= hourly resolutions, the observed discharge is a set of discrete measurements of an otherwise time-continuous (TC) quantity, but the modelled discharge is time-averaged (TA) across the fixed timestep. Hence the commensurability error when compared against one another during calibration. (In)significance of such errors simultaneously depends on the nonlinearity of the discharge within that timestep, and the timestep size. Consequently, these errors are the largest where they are potentially least acceptable to ignore, i.e., around peaks. Also, they tend to grow with timestep size (data resolution), unless timestep is detached from data resolution using adaptive schemes, which produce a TC solution. Importantly, since modern calibration procedures revolve around ‘fitting’ to observed discharge, such errors are likely undetectable in model’s curve-fitting performance, and instead are to be found in calibrated parameter-sets. Here, in a novel approach within the Generalize Likelihood Uncertainty Estimation (GLUE) framework with Limits of Acceptability (LOA) defined a-priori, and for a micro-catchment case study, we calibrate a TA and a TC version of Dynamic-TOPMODEL to datasets at different resolutions. Through experimentation with the calibrated parameter-sets, we estimate the relative (to TC version) magnitude of the time-commensurability errors resulting from fixing the timestep to input rainfall. Our findings confirm the overall insufficient accuracy, inefficiency of timestepping, and inconsistency across resolution when fixing the timestep. We find that for calibration data resolution >10min, time-commensurability errors become very significant.

Freshwater from rivers influences Indian summer monsoon rainfall and tropical cyclones by stratifying the upper layer and warming the subsurface ocean in the Bay of Bengal. Here, we use {\it in situ} and satellite data with reanalysis to showcase how river water experiences a significant increase in salinity on sub-seasonal timescales. This involves the trapping and homogenization of freshwater by a cyclonic eddy in the Bay. Using a specific example from 2015, river water is shown to enter an eddy along its attracting manifolds within a period of two weeks. This leads to the formation of a highly stratified subsurface layer within the eddy. When freshest, the eddy has the largest sea-level anomaly, spins fastest, and supports strong lateral gradients in salinity. Subsequently, observations reveal a progressive increase in salinity inside the eddy within a month. In particular, salty water spirals in, and freshwater is pulled out across the eddy boundary. Lagrangian experiments elucidate this process, whereby horizontal chaotic mixing provides a mechanism for the rapid increase in surface salinity. A salinity budget also suggests that horizontal advection explains much of the change in mixed layer salinity. Further, the adjustment of this freshwater eddy triggers submesoscale dynamics which appear to be an integral part of the process of salinity homogenization. This pathway is distinct from vertical diffusive mixing and is likely to be important for the evolution of salinity in the Bay of Bengal.

The Open Global Glacier Model (http://oggm.org) is an open source modelling framework, helping various research groups to simulate and understand mountain glacier change at the regional or global scale. OGGM is modular, which means that we encourage users to develop their own physical parameterizations while staying compatible with the OGGM workflow. To achieve this goal, we need OGGM to be easy to understand, install, apply, and extend. In this presentation, I will talk about how we make use of the wealth of open-source tools available in the python and Jupyter ecosystems to provide an online documentation platform for OGGM. Our documentation combines text with interactive examples that run in your web browser, avoiding the typical installation and data download burden for newcomers. With selected examples from the collaborative educational content platform OGGM-Edu (http://edu.oggm.org), I will show how anyone can apply these ideas and tools to their own documentation or outreach project. Finally, I will talk about some of the challenges faced by the OGGM project in its pursuit of becoming a community model. With the increasing pressure on geoscientists who have to learn new complex technologies while navigating the “publish or perish” career model, the growing demand for better open science practices can be a blessing as well as a curse for many early career scientists.

Positive and negative electric streamers are column-shaped discharges which are an important stage in lightning development. The mechanism, by which the streamer acquires a certain velocity and radius of its head, had been a long-standing puzzle. In [1], we proposed a parametric streamer model (PSM), which may explain this mechanism, as well as the mechanism of the streamer threshold electric field. The PSM results for a positive isolated streamer in constant uniform external electric field are verified by comparing with hydrodynamic calculations of a ‘steady-state’ streamer, namely a streamer whose length is kept constant by synchronizing the position of the electrode to which it is attached with the moving streamer head. For this particular streamer configuration, we found that both velocity and radius of a streamer increase with its length, a results which was also observed in previously performed hydrodynamic calculations and experiments. Beside the velocity and radius of the streamer, PSM allows to quickly estimate all other streamer parameters, such as the maximum field at the streamer tip and the field inside the streamer channel. The relatively low, compared to, e.g., hydrodynamic or particle-in-cell (PIC) models, computational costs of PSM suggest that generalizion of PSM principles to more complicated streamer structures may be very valuable. In the present work, we generalize PSM to evaluate how different background conditions affect streamer propagation. In particular, we find that, unlike the uniform-field case described above, (1) for the non-uniform electric field such as that of a spherical electrode, the streamer velocity decreases with length; (2) for a streamer propagating parallel to other similar streamers (as in a streamer “bunch’‘), both velocity and radius stabilize to an approximately constant value. [1] N. G. Lehtinen, “Physics and mathematics of electric streamers,” Radiophysics and Quantum Electronics, 2021, in print [Russian version: DOI: 10.52452/00213462_2021_64_01_12].

Many of the unusual properties of the dwarf planet Pluto's orbit are widely accepted as evidence for the orbital migration of the giant planets in early solar system history. However, some properties remain an enigma. Pluto's long term orbital stability is supported by two special properties of its orbit that limit the location of its perihelion in azimuth and in latitude. We revisit Pluto's orbital dynamics with a view to elucidating the individual and collective gravitational effects of the giant planets on its perihelion location. In this presentation we demonstrate with numerical experiments that, while the resonant perturbations from Neptune account for the azimuthal constraint on Pluto's perihelion location, the long term and steady persistence of the latitudinal constraint is possible only in a narrow range of additional secular forcing which arises fortuitously from the particular orbital architecture of the other giant planets. Our numerical investigations also find that Jupiter has a largely stabilizing influence whereas Uranus has a largely destabilizing influence on Pluto's orbit.

The search for evidence of existing or extant Life (biosignatures) is a growing research topic and one of the main pillars of Astrobiology. There is significant interest in the search and exploration of new biosignatures, and increasing relevance of Potential Biosignatures. These are specific features that although consistent with biological processes can also be attributed to inanimate processes. Biogenic Metallic nanoparticles (MNPs), have been intensively studied and explored, yet their synthesis is not yet fully understood. Despite the lack of a systematic survey on this topic, it is well known that many microbes produce molecules with the capability of reducing metal ions. Given the wide diversity of such molecules, we can assume that all microbial life is capable of synthesizing them and, consequently, producing MNPs. Researchers agree that any existing or extant life on Mars or on other parts of the solar system, is (or was) likely microbial. Therefore, the detection of MNPs formation, when analyzing extraterrestrial samples (e.g., sediments, rocks), could be used to infer the presence of biological molecules and thus be employed as a new potential biosignature. Therefore, in short: yes, biogenic metallic nanoparticles have a great potential of being used as biosignatures.