Galactic Origin of the Solar System
Abstract
The Solar System formed nearly 4.6 billion years ago within an evolving Milky Way shaped by stellar nucleosynthesis, chemical enrichment, dynamical mixing, and stellar motion. However, fundamental questions still remain unresolved: where in the Galaxy did the Solar System originate, was the Sun born at its present Galactic location, and how can the early Galactic environment of the Solar System be reconstructed today? Observational evidence from Galactic metallicity gradients, stellar dynamics, meteorites, and presolar grains suggests that the Solar System may preserve signatures of a complex Galactic history. Presolar grains, microscopic stardust particles embedded within primitive meteorites, retain isotopic fingerprints of stellar environments predating the Solar System itself and therefore act as astrophysical archives of Galactic evolution.
In this seminar, I shall discuss the present understanding of the Galactic origin and migration of the Solar System, the role of Galactic Chemical Evolution in shaping the Milky Way, and how isotopic signatures preserved in presolar grains can provide new perspectives toward tracing the possible Galactic journey of our Solar System.
Gas-Coupled Ultrasound Sensing for Planetary Science
Abstract
The study of planetary atmospheres is important for understanding the theories of planetary evolution and origin, and climate dynamics. In this work, I will discuss two novel ultrasonic techniques aimed at achieving two distinct measurement objectives: wind measurement on Mars and determining atmospheric gas composition for the giant planets. On Mars, accurate wind measurements are essential for characterizing atmospheric dynamics, dust lifting and transport processes, and improving climate models. A sonic anemometer was developed with a 19 cm path length and a 400 g of mass. Three-dimensional wind measurements were conducted in low-pressure Martian environment conditions at flow speeds from 0 to 11 m/s in various orientations in the Aarhus Mars Simulation Wind Tunnel. A resolution of 2.4 cm/s was achieved with an update rate of 4.2 three-dimensional wind samples per second. Helium abundance on Saturn/Uranus remains a long-standing open question, limiting understanding of theories of planetary formation. Determining the ortho/para hydrogen spin isomer is important for understanding atmospheric structure and dynamics. An ultrasonic technique was developed for determining the helium abundance and ortho/para hydrogen ratio for the giant planets. Computational results imply a resolution of 0.78% for helium abundance and 4.96% for ortho/para ratio at 500kHz over different pressures, temperature, and concentrations. Experimental measurements of helium abundance in H2:He mixtures were conducted at 0.5-7bar and 292K over 100kHz to 1MHz. The concentration was calculated using the sound speed and a maximum error of ±5.9 % was observed (limited by the experimental setup, not by the ultrasonic technique).
Modeling and Analysis of Main-Belt Asteroidal Dust Flux and Velocity Distribution at Inner Planets
Abstract
The inner solar system is continuously replenished by a steady stream of dust, originating from multiple sources including comets and asteroids. In this talk, I shall focus specifically on the dynamical evolution of asteroid-derived dust and its contribution to planetary impact environments across the terrestrial planets. I shall present results from N-body simulations that trace the orbital evolution of asteroidal dust under solar gravity, planetary perturbations, radiation pressure, Poynting-Robertson drag, and solar wind forces. I shall elaborate on how we calibrate dust fluxes at Mars, Venus, and Mercury against multiple independent observational datasets - an approach that minimizes systematic biases inherent in single-source calibrations. I shall further demonstrate evidence for mean-motion resonance trapping during inward migration. A central outcome of this talk is a decoupling between dust impact flux and impact velocity, and how encounter velocities vary with the apsidal orientation of dust orbits - together revealing a more complete picture of impact-driven processes across the inner solar system.
Streamlined Islands on Earth and Mars
Abstract
Streamlined Islands (SIs) act as key geological signatures for decoding extreme hydrological events on Mars. In this study, we performed a morphometric analysis of 658 SIs within the Chryse Planitia (CP) outflow channels to constrain the nature of their formation. Using methods including lemniscate fitting and calculating length-to-width (L/W) ratios, we classified the features, identifying 544 as erosional mesas and 114 as crater-controlled remnants. The mean L/W ratio for the Martian population is 2.89 ± 1.23, which is statistically congruent with the mean L/W ratios observed in terrestrial megaflood features such as those in the English Channel (3.42 ± 1.3), supporting the optimal L/W range of 3 to 4 associated with minimum fluid drag. This geometric consistency, along with evidence of elevation continuity confirming erosional bedrock remnants, suggests the SIs were formed by unconfined, catastrophic flooding events, similar to those that shaped the English Channel. The influence of pre-existing impact craters, which introduced complexity through buried, double, and eroded configurations, further characterizes the localized interaction between massive fluvial erosion and underlying topography. The presence of these streamline shaped islands further adds to the evidence that a large amount of liquid water had flown, on the surface of Mars, through these outflow channels in the form of Megafloods.
Clues to Martian Interior Processes from Meteorites
Abstract
Shergottites comprise ~90% of the known Martian meteorite inventory. Poikilitic shergottites are distinct as coarse-grained cumulates that crystallized at greater depths within Mars, in contrast to the predominantly extrusive nature of basaltic varieties. This talk focuses on a detailed study of poikilitic shergottites to constrain Martian igneous processes delineate mantle source heterogeneities, and evaluate their coupling with crustal evolution. This study attributes to the reconstruction of magma evolution pathways, from deep-seated melt generation to ascent, highlighting the connection of a gap area in our understanding of Martian mantle.
Low-Energy Gamma-Ray Continuum as a Tool for Water Ice Detection on the Moon
Abstract
The detection and quantification of water ice in the lunar subsurface remains a central objective for future planetary exploration missions, particularly in polar and permanently shadowed regions. While neutron spectroscopy remains a highly sensitive technique for hydrogen detection, this work explores a complementary approach using low-energy gamma-ray continuum measurements below 500 keV.
A Geant4-based Monte Carlo simulation framework has been developed to model the interaction of galactic cosmic rays with the lunar regolith and estimate the resulting gamma-ray continuum and neutron leakage spectra. Simulations were carried out for three lunar compositions — the Chandrayaan-3 landing site, Apollo 17 Mare basalt, and norite — under both homogeneous and layered water ice distribution models.
In this seminar, I will present the simulation methodology, the key results from the gamma-ray continuum and epithermal neutron analyses, and their implications for lunar water ice detection.
Investigation of Whistler Waves Associated with Flux Rope near Venus
Abstract
Whistler waves are electromagnetic plasma waves with a characteristic frequency and mode of propagation. These waves can be generated by various means in the planetary plasma environment, including atmospheric lightning on Venus and Earth. Whistler waves have therefore been considered as potential evidence of lightning activity on Venus and are predominantly observed in the nightside ionosphere, possibly associated with lower-atmospheric sources. On Earth, these waves are frequently observed in the magnetic reconnection region, with only limited observations reported in association with flux rope structures, where they are generated under local plasma conditions such as temperature anisotropy. Few flux rope structures have been reported on Venus, which are associated with magnetic reconnection. However, whistler waves associated with flux ropes near Venus are yet to be fully understood. In this seminar, I’ll talk about the whistler waves observed in the vicinity of Venusian flux rope structures, their properties and associated local plasma conditions. This work provides new insight into Venusian whistler wave activity and may lead to further studies of whistler waves driven by local plasma instabilities.
Novel detection and Geochemical Characterization of Lunar Pyroclastic Deposits
Abstract
Lunar pyroclastic deposits (LPDs) are very low albedo, fine grained and smooth homogeneous lithological unit often composed of Fe-Ti-bearing volcanic glasses. Lunar pyroclasts are considered as one of the best proxies to understand primitive mantle composition, volatile inventory and thermal evolution of the Moon. However, due to morphological similarities, overlapping spectral signatures between volcanic glasses and common lunar minerals (e.g., olivine and pyroxene) in the visible to near-infrared wavelength range, and limited spatial resolution data, remote discrimination of these explosive volcanic deposits was challenging from effusive mare units.
In this seminar, I will present a newly proposed integrated framework for detection of LPDs and a hyperspectral unmixing approach for the statistical estimation of volcanic glass as well as constituent minerals abundances across those deposits. The framework has been validated using previously identified pyroclastic deposits and demonstrates the capability to detect ~85% of the reported LPDs at a global scale. This systematic global survey led to the identification of nine new sparsely distributed LPDs. The geochemical characterization reveals, similarity of these nine deposits to the bulk composition of Apollo returned yellow volcanic glasses. Their geochemical implications towards understanding the role of lunar mantle overturn will also be discussed.
Magmatism in the Freundlich-Sharonov Basin on the Far Side of the Moon
Abstract
In the earliest epochs of lunar geological history, the Moon experienced extensive impact bombardment, resulting in the formation of numerous large impact basins and craters. These impact events have significantly influenced the regional geomorphology and magmatic processes on the Moon. The Freundlich-Sharonov Basin (FS Basin; 18.35ºN, 175.2ºE) is a ~600 km diameter multi-ring impact basin located on the farside of the Moon, which exhibits a spatially restricted and volumetrically limited volcanic activity confined within the central depression and along the newly identified inner depression ring, providing an ideal geological setting to investigate the initial phases of volcanism within the impact basins. In this seminar, I will present a detailed compositional and spectral analysis of the FS Basin conducted using Kaguya elemental maps and Moon Mineralogy Mapper (M3) hyperspectral datasets, which reveal late-phase high-alumina volcanism on the Moon extending up to ~2.1 Ga. An in-depth understanding of the composition of volcanic emplacements, in conjunction with the geomorphological setting of the FS Basin, provides a key opportunity to comprehend the controls on lunar magmatism in a thick, KREEP-poor farside crust. These insights will be valuable for understanding magmatism in other similar large-scale impact basins.
A 3D thermophysical model for Mars – Development and Validation
Abstract
Understanding diurnal surface temperature variations on Mars is
essential for interpreting the thermophysical properties of the
regolith and for assessing surface–atmosphere energy exchange relevant
to planetary processes and mission operations. Most current
interpretations of Martian surface temperatures rely on 1D
thermophysical models, among which the KRC model has been widely used
for analyzing orbital and in-situ thermal observations. While these
models successfully reproduce the overall diurnal temperature cycle,
they cannot explicitly capture lateral heat transport, differential
solar forcing due to local slopes, terrain shadowing, or spatial
variability associated with surface roughness and complex topography.
To address these, a comprehensive 3D thermophysical model for the
Martian surface is developed using the finite element method and
validated using earlier model simulations and in-situ observations.
Model details and its application to certain specific sites will be
discussed.
Chronology and Genealogy of Early Solar System Materials from Chromium Isotopes
Abstract
Our solar system formed ca. 4,567 Ma ago from the collapse of a dense core within an interstellar molecular cloud. Determining the timescales (chronological studies) of the accretion of planetesimals that later formed the terrestrial planets and asteroids, and linking this information to the source reservoirs of their precursor materials (genealogical studies), are key to understanding the temporal and spatial constraints on early solar system processes. Meteorites, rocks that formed during the early stages of the solar system and made their way to Earth, are our most powerful means to retrace the formation, transport, and evolution of early planetesimals at different times and locations within the protoplanetary disk and beyond. They sample various asteroids, the Moon, and Mars, and are the most accessible source of extraterrestrial matter for direct study in the laboratory. This presentation discusses the chronology and genealogy of various solar system materials using high-precision Cr isotopes as chronological and genealogical tools. These studies are based on the determination of radiogenic and nucleosynthetic Cr isotope variations in meteorites and terrestrial impactites with meteoritic contamination
Geochemical Signatures of Archean Banded Iron Formations: Implications for hematite on Mars
Abstract
The Archean Dharwar Craton of southern India preserves volcano-sedimentary greenstone belts that record early Earth crustal evolution, tectonic processes, and ocean–atmosphere chemistry. The Dharwar Craton hosts well-preserved Banded Iron Formations (BIFs) within volcano-sedimentary greenstone belts. Integrated field observations, mineralogical analyses, and whole-rock major, trace, and rare earth element (REE) geochemistry of the BIFs (spanning ~3300–2600 Ma) reveal distinct paleoenvironmental signatures. Low total REE contents, positive Eu anomalies, and characteristic trace-element ratios indicate a dominant hydrothermal source for iron, and the variable Ce anomalies suggest fluctuating redox conditions in the Archean ocean–atmosphere system. Variations in mineral facies and Fe–Si systematics, together with localized enrichment in Al₂O₃ and CaO, reflect basin-scale heterogeneity and minor detrital input during BIF deposition. Building on these findings, future research will extend these mineralogical and geochemical approaches to planetary environments, particularly Mars. Comprehensive studies of the characteristics of terrestrial hematite are necessary to establish a basis for understanding hematite found on Mars, since sample return from Mars is still a distant prospect. Additionally, hematite, a major iron oxide phase in BIFs, is also a key indicator of aqueous activity, oxidation processes and habitability on Mars. By integrating hematite from diverse geological settings on Earth, particularly from the Indian geological record, this work aims to establish robust terrestrial analogues for Martian hematite formation, providing new insights into oxidation processes, validation of rover-based data and the evolution of early Martian surface environments.
Solar Forcing and Electron Temperature Control of the Venusian Topside Ionospheric Bulge
Abstract
The dayside ionosphere of Venus exhibits a recurring electron density enhancement known as the "topside bulge". It has been reported by multiple missions, yet its formation mechanisms remain debated. Using over 200 dayside electron density profiles from the Venus Radio Science experiment (VeRa) onboard Venus Express (2006–2014), we classify bulges into three types using an automated, gradient-based method. Type 1 bulges are found at higher altitudes, whereas Type 2 and Type 3 bulges occur at comparatively lower altitudes within the photochemistry-dominated region above the V2 layer.
In this seminar, after discussing the morphological differences and occurrence rates of these bulge types, I will demonstrate the necessity of correcting for solar flux at Venus by accounting for both heliocentric distance and solar rotation in order to accurately characterize the primary V2 layer. Using the built-in house 1D photochemical model, I will discuss how vertical variations in electron temperature influence the structure of the topside ionosphere and shape the observed bulge morphology within the photochemically dominated regime.
Characterising Insoluble to Soluble Organic Matter by Spectroscopy and Machine Learning: Tracing Organic Reservoirs in Asteroidal Samples
Abstract
Asteroidal materials contain diverse organic matter (OM) components that are heterogeneously distributed within their mineral matrices. Organic matter occurs as either soluble organic matter (SOM) or insoluble organic matter (IOM). IOM is a complex macromolecular polymer spanning nanometer- to micrometer-scale, whereas SOM consists of relatively simple organic compounds bearing functional groups and is extractable using solvents such as water, methanol, and dichloromethane. Due to its insoluble nature, IOM can be characterized using petrographic, surface, and bulk analytical techniques, while SOM is primarily accessible through bulk molecular and isotopic analyses. My PhD research focused on the systematic characterization of IOM through the development of a novel SEM–EDS–based workflow integrating image processing and machine learning, which enabled unbiased identification of two distinct organic phases: concentrated organic matter (COM) and diffuse organic matter (DOM). COM exhibits petrographic properties analogous to classical IOM in terms of contrast, size, and spatial distribution, whereas DOM displays distinct characteristics. Based on these observations, I hypothesize that DOM may represent the petrographic expression of SOM within the matrix. To test this hypothesis, I propose to extend this work to direct SOM characterization at PRL by extracting SOM from sample aliquots and analyzing its molecular, spectral, and isotopic properties using FTIR, Raman spectroscopy, and NanoSIMS. Comparative isotopic analyses of aliquots before and after SOM extraction will be used to assess the contribution of SOM to the overall isotopic signature. Confirmation of this hypothesis would suggest distinct accretion sources for SOM and IOM, whereas its rejection would imply multiple sources or temporal variations in organic matter accretion within carbonaceous chondrite parent bodies.
From Automated Crater Mapping to Mantle Probing in the SPA Basin
Abstract
Impact cratering exerts a primary control on the geological evolution of planetary bodies and serves as a key proxy for relative chronology, resurfacing processes, and crustal modification. Although major crater catalogs exist for the Moon and Mars, completeness declines at smaller diameters where manual mapping becomes laborious and observers differ in detection thresholds. Automated crater detection pipelines have advanced substantially with the introduction of classical machine learning, deep convolutional detectors, transformer-based architectures, and fusion of optical imagery with topography. These approaches improve recall for small and degraded craters, and support near-real-time inference, with potential utility for crater size–frequency distribution studies, surface chronology, and terrain-relative navigation. Building on these developments, the South Pole–Aitken Basin provides an exceptional natural laboratory for probing deep lunar lithologies. Multiple lines of evidence suggest that the SPA-forming impact may have excavated crustal and possible mantle materials, enabling investigation of Lunar Magma Ocean differentiation, the distribution of pyroxene and olivine lithologies, and the presence or depletion of KREEP during early lunar evolution. The proposed research integrates hyperspectral, geochemical, and contextual datasets with supervised and deep learning classification to evaluate mantle signatures at SPA, assess their geological context, and quantify implications for crust–mantle stratigraphy. The expected outcomes are relevant to lunar science priorities including landing site characterization, sample return targeting, and comparative studies of early solar system impact environments.
Study of interactions between gas-phase oxygen- and carbon-bearing species and interstellar ice analogs
Abstract
Oxygen and carbon are among the most abundant elements in the universe, forming the molecules that shape the environments of planets, comets, and interstellar space. However, the observed gas-phase abundances of oxygen- and carbon-bearing species in dense molecular clouds and cold regions of protoplanetary disks are significantly lower than predicted. This discrepancy suggests that much of these elements is trapped in icy mantles on dust grains. The structure of these icy mantles, whether crystalline, nonporous amorphous, or porous amorphous, plays a critical role in how molecules adsorb, diffuse, and desorb, yet the underlying surface processes remain poorly understood. This study employs ultra-high vacuum laboratory experiments using Reflection Absorption Infrared Spectroscopy (RAIRS) and Temperature Programmed Desorption (TPD) to investigate molecular interactions with interstellar ice analogues. RAIRS will be used to probe hydrogen bonding,molecular orientation, and structural changes, while TPD will quantify desorption kinetics and binding energies. By systematically exploring the relationship between molecular chemistry and ice morphology, this research aims to clarify the processes of retention and release of key oxygen- andcarbon-bearing species.
Interpreting Cometary Production Rates: The Role of Nucleus Shape and Illumination Geometry
Abstract
Observed cometary production rates are often treated as straightforward measures of activity, but in practice they depend strongly on the physical characteristics of the nucleus. Properties such as shape, rotation state, and illumination conditions can change how much of the surface is effectively active at different points along the orbit. As a result, variations in production rates do not necessarily reflect changes in composition or heliocentric distance alone. In most research work spherical shape and uniform activity is taken to model the nuclues which can mask important physical effects and lead to misleading interpretations of outgassing behavior. In this seminar, I will explore how nucleus geometry and orientation influence observed production rates and discuss why more realistic representations of cometary nuclei are needed to better link observations with the physical state and evolution of comets.
Serpents and Sources: Investigating Enigmatic Sinuous Aurora at Mars with EMM and MAVEN
Abstract
Nightside aurorae at Mars are produced when electrons precipitate into the upper atmosphere generating photon emissions. The Emirates Mars Mission (EMM) provides full-disk far-ultraviolet imaging with Emirates Mars Ultraviolet Spectrometer (EMUS), revealing three discrete aurora types: crustal field aurora, patchy aurora, and sinuous aurora. Concurrent in-situ MAVEN observations confirm that supra-thermal electron flux enhancements (less than 1 keV) drive elevated nightside ionospheric densities and auroral emissions. Electron pitch-angle distributions indicate precipitation along open magnetic field lines, characterized by field-aligned electron flow. During a conjunction event, EMUS and MAVEN data show that sinuous aurora correlate with magnetotail current sheet. Based on their attributes, sinuous aurora appears to be a projection of the tail current sheet under conditions which allow energized electrons to populate it. The current sheet itself is a persistent yet highly variable feature of Mars’ double-lobed magnetotail resulting from the draping of the IMF around the Martian ionosphere.
