Resurrection of Elements in the Milky Way: A MCMC Recipe
Abstract
The formation and chemical evolution of the Milky Way are traced through the continuous cycle of stellar birth, death, and enrichment, wherein each generation of stars contributes to the resurrection of elements in the interstellar medium. In this work, we present a Monte Carlo Markov Chain (MCMC) framework developed to model the Galactic Chemical Evolution (GCE) of 83 isotopes spanning 32 elements, employing updated stellar yields. The MCMC approach enables efficient sampling of the complex, multi-dimensional parameter space governing the Galaxy’s star formation rate, initial mass function, and supernova contributions, thereby constraining these parameters against observed elemental abundance distributions.
Our simulation reproduces the observed chemical trends across the various regions of the Milky Way, offering insights into the dynamic interplay between stellar nucleosynthesis and Galactic assembly. The results highlight how the ashes of long-dead stars continually reforge the building blocks of new generations: a recursive process central to both the chemical and structural evolution of our Galaxy.
Planetary Differentiation and Sample Analysis
Abstract
After accretion from dust, gas, and rock colliding and sticking together, Planetary differentiation is the process by which a planet's molten materials separate into distinct layers. Following this early stage of planetary evolution, the differentiation process continues for billions of years and may still be ongoing today, owing to the internal dynamics of each planet. Over the past decade, planetary missions—especially to the Moon and Mars, as well as the growing number of recognized lunar and Martian meteorites — have provided transformational insights into the diversity, composition, and histories of planetary materials throughout the inner Solar System. Yet, despite these new insights, defining a reasonably simple set of criteria that provides some predictive understanding of planetary crustal development remains elusive. This talk will try to showcase the elusive characteristics of our understanding towards planetary evolution through the proxy of extra-terrestrial sample analysis.
Interplanetary Dust and Its Measurement in Solar System
Abstract
Our solar system is immersed in a thin cloud of Interplanetary Dust Particles (IDPs). The dust is an important constituent in formation of solar system and found everywhere. The IDP may originate from sources like Asteroid belt, Kuiper belt or comets and evolve dynamically under the influence of various forces. Although, there are some measurements of IDP near Earth and also, in the interplanetary space; there are no measurements of IDP at other inner planets. The entering dust particles in a planetary object can affect it in different ways. During the seminar, the results of IDP flux in inner solar system will be presented. The Dust EXperiment (DEX) was flown recently using POEM 3 on PS4 of PSLV C-58 (XPoSat) mission to understand dust particles in the Earth orbit. From the dust observations in near Earth orbit, the DEX was found working successfully in space. The results obtained from DEX will be also be presented
Investigating Lunar Subsurface Water Ice through Neutron Leakage and Gamma-Ray Continuum Flux
Abstract
Lunar volatiles, including water ice, are considered to be preserved in cold traps or buried beneath the surface layer near the poles. Understanding their distribution and abundance is critical for advancing knowledge of lunar evolution and for supporting future exploration activities. Neutron and gamma-ray spectroscopy provide key tools for this purpose, as subsurface hydrogen abundance can be inferred to depths of up to 1 m from measurements of neutron leakage flux and gamma-ray continuum flux from the Moon.
In this seminar, I will discuss the lunar leakage neutron and gamma continuum flux induced by galactic cosmic rays interacting with the lunar surface, as well as their dependence on subsurface hydrogen abundances, using Monte Carlo simulations. The effects of temperature and compositional variation on neutron leakage flux are examined. The sensitivity of the leakage neutron intensity to the depth profile of subsurface water ice within the top 1 m of soil will also be discussed.
MXene in LEO: A Technology Demonstration of Nano-Biomaterial Devices in the ISS with Axiom 4 Mission
Abstract
MXenes are a family of two-dimensional nanomaterials made of metal carbides/nitrides/carbonitrides. The inorganic compound of MXenes, first reported in 2011 (titanium carbide, Ti3C2TX-MXene), has found various terrestrial applications like supercapacitors, sensors, electromagnetic shielding, chemical sensors, wearable devices, biomedical and implantable devices, multifunctional coatings, etc. Some of the unique properties of MXenes (particularly, Ti3C2TX-MXene) are film-forming ability, hydrophilic behavior, low electrical resistivity, good elasticity, field-electron mobility of, and fast dynamic response behavior. The possibility of hundreds of unique stoichiometric MXene combinations, reported to date, results in achieving wide tunability of physical and chemical properties by varying ratios of metal and carbide/nitrides/carbonitrides.
After exhaustive testing and validation of the MXene devices in terrestrial environment, the speaker and his team were the first to test the MXene devices with several stratosphere flights from 2022. Building on the results from real environment testing of MXene nanomaterial and its devices, MXene in LEO (MXene Material and Wearable Device Experiments in Low-Earth Orbit Space Habitat) was proposed as part of the IGNIS mission of the European Space Agency and Polish Space Agency, forming a part of the Axiom 4 mission.
MXene in LEO is a unique technology demonstration in the low-Earth orbit (International Space Station) using multifunctional nanomaterial (MXene) and sustainable biomaterial (bacterial cellulose) to form nano-biomaterial devices for human health monitoring in space. The first objective of the experiment was to test the environmental stability of MXene nanomaterial inside the space station. The second objective was to test the possibility of detecting hand movement and pulse of the human subject wearing the MXene wristbands in the space station. With the accomplishment of both objectives, the technology demonstrator provides a foreground for wider usage of MXene nanomaterials in space applications and their direct impact on terrestrial activities.
Exploring Fluvial activity around the circum-chryse basin on Mars
Abstract
The Chryse Planitia is an asymmetrical basin centred at approximately 45oW and 24oN, about 2000 km northeast of Valles Marineris. It has a diameter of ~1600 km and is 2-3 km below the mean Mars elevation. This basin receives deposits from several major outflow channel systems. Two principal groups of channels terminate in this basin. The first originates from chaotic terrains near the eastern end of Valles Marineris and flows northward for over 1000 km into the southern part of the basin. This group includes Ares Vallis, Tiu Vallis, Simud Vallis, and Shalbatana Vallis. The second group, dominated by Kasei Vallis, enters the basin from the west. As such, Chryse Planitia receives sediment and water input from two widely separated source regions spanning over 2500 km.
In this seminar I will discuss the interaction of the major fluvial channels with the rim of Chryse Planitia basin. I will be discussing a new method for estimating the discharge, volume and timescales of fluvial activities around the circum-chryse region. This new method involves simulation for Unsteady flow analysis through which I would be exploring one of the largest dam-break scenarios in the solar system.
Linear and Nonlinear Excitations in Rotating Dusty Plasmas across Coupling Regimes
Abstract
Dusty plasmas consisting of dust particles, electrons and ions, can be found in various states of matter (solid, liquid, and gaseous) [1-3]. They, therefore, cover a broad range of parameter space relevant to both astrophysics as well as laboratory environments. Studies of the collective excitations in dusty plasmas provide valuable insights into their static and dynamic properties, as well as how these excitations can be controlled for practical applications [4-7]. For example, investigations of these excitations in the strongly coupled limit can be relevant to ion trap systems where the phonon mode spectrum is manipulated to enhance quantum gate performance efficiency [8]. From an astrophysical perspective, recent dusty plasma experiments have observed nonlinear excitations, such as pinned, precures solitons, generated by a moving charged obstacle [9]. These observations motivate the idea of indirect detection of space debris in the ionosphere through such structures[10]. In this talk, I first discuss magnetoplasmon excitations in rotating dusty plasma equilibria that can be generated in the absence of non-conservative fields [1-2]. These magnetoplasmon signatures have been observed in the absence of a real magnetic field across a wide range of dusty plasmas parameter [1]. Then, I address the nonlinear excitations such as Korteweg-De Vries (KdV) Soliton, pinned, precursor solitons in non-rotating dusty plasmas. The characterization of KdV Soliton structures is presented in details under the existing models to test their reliability, and new models are proposed to overcome their limitations [6-7]. Finally, I discuss the pinned and precursor solitons, which are induced in the medium by a moving charged source, appearing at and ahead the source, respectively, under specific Mach number values. The potential applications of these structures for detecting space debris in the lower Earth orbit (LEO) region of the ionosphere are also outlined.
Exploration of the Venus and Lunar Ionosphere Using Radio Science Experiments
Abstract
Venus and the Moon, our two neighbouring celestial bodies, exhibit extreme contrasts in atmospheric conditions. Venus has a neutral density nearly 90 times that of Earth, while the Moon has an almost negligible atmosphere. Despite these differences, both bodies possess significant ionized layers capable of affecting radio signal propagation. This seminar will focus on the characteristics of these ionospheric layers as revealed through radio occultation experiments, with comparisons to Earth’s ionosphere. We will also discuss the implications of these findings for future exploration.
Chandrayaan-3 Pragyan Rover at Shiv Shakti Statio: Findings from APXS In Situ Geochemical Measurements and Contextual Remote Sensing Analysis
Abstract
The Chandrayaan-3 mission is the first successful soft-landing at the Shiv Shakti statio (located at 69.37°S, 32.32°E) in the south polar region of the Moon. During the mission, the Pragyan rover traversed around 103 m on the lunar surface within a single lunar day. Onboard the rover was an instrument called the Alpha Particle X-ray Spectrometer (APXS), which measured the elemental composition of the Moon’s surface. The abundance measurements of major elements supported the widely accepted lunar magma ocean (LMO) hypothesis, which suggests that the early Moon was once covered by a global layer of molten material. In addition to major elements, the APXS also measured the abundance of volatile elements including sodium, potassium, and sulfur at the landing site, which varied in concentrations ranging from 700-2800 ppm, 300-400 ppm, and 900-1400 ppm, respectively. The detailed comparison and analysis of volatile abundances with the measurements in soil samples collected in earlier missions (Apollo 16 and Luna 20) revealed that there is anomalous depletion in sodium and potassium, but enrichment in sulfur in the soils at the Chandrayaan-3 landing site. One possible source of sulfur in lunar soils is Type I Carbonaceous chondrites (CC), which can add approximately 400-1000 ppm of sulfur into the lunar soil. However, this alone cannot explain the excess of 200-400 ppm sulfur observed at the Chandrayaan-3 landing site. In this case, there has to be another source of sulfur that increased its concentration at the landing site. Toward the end of the LMO crystallization stages, around 4.3 Ga ago, the residual molten layer in the lunar mantle became enriched in a mineral called Troilite (FeS), which contains sulfur. Around the same time, a giant impact created the South Pole-Aitken (SPA) basin, which is one of largest and oldest impact basins in the solar system, approximately 2,500 km wide. This massive impact likely excavated this sulfur-rich troilite from the Moon’s interior, when the KREEP (potassium, rare earth elements, and phosphorus) layer was not adequately formed. The subsequent impacts on SPA basin ejecta resulted in further stirring of the materials across the region, possibly redistributing it at the Chandrayaan-3 landing site. To summarize, the Chandrayaan-3 landing site hosts sulfur-rich material from the Moon’s primitive mantle, which was excavated by the SPA basin impact billions of years ago. This makes the Chandrayaan-3 landing site a valuable place for accessing samples from the mantle of the Moon, which is otherwise lacking in the existing lunar collections. These samples would offer a rare opportunity to study about the early evolution of the Moon.
Lunar Polar Water-Ice: Current Understanding and New Insights from ShadowCam
Abstract
Our understanding of lunar volatiles is significantly improved using multi orbiter data-sets and reanalyzing returned samples. Multiple observational evidences suggest that water-ice is predominantly concentrated within permanently shadowed regions (PSRs) near the lunar poles, which are also the prime targets for future lunar exploration. With the current limitations of observational datasets, the occurrence, content, distribution and source of water-ice in PSRs are yet to be answered.
In this work, we used ShadowCam, a high-resolution imaging system aboard the Korea Pathfinder Lunar Orbiter (KPLO) for understanding the PSR morphology. ShadowCam offers unprecedented views into these shadowed terrains, allowing detailed analyses of surface textures and reflectance anomalies that may indicate water-ice presence. Here, I will present the initial results from our analysis using ShadowCam data, investigating surface reflectance behaviour of PSRs from south pole, highlighting the reflectance variations that might indicate the distribution of water-ice at and within different PSRs.
Recent boulder falls on Planetary bodies: Insight into recent activities
Abstract
Rockfalls or boulder falls on Earth are very common and occur almost daily in certain parts of the world. In contrast, rockfalls on Mars are rare, and no rockfalls have been reported on the Moon in the last decade. This difference underscores the value of studying boulder falls on planetary bodies, as they provide important insights into geological processes. On planetary bodies like Mars and the Moon, millions of boulders/rocks are present on the surface, formed through the weathering of the crust, impact breccia’s, and other geological processes. These boulders vary in size, ranging from a few meters to several tens or even hundreds of meters. On the Moon, these boulders are particularly abundant. To date, using the latest high-resolution images from the Chandrayaan-2 Orbiter High-Resolution Camera (OHRC) and Lunar Reconnaissance Orbiter Narrow Angle Camera (LRO-NAC) there is no report of recent movement of even a single boulder over the past decade. This brings an intriguing question: do all the boulders on the Moon have reached equilibrium, or have there been movements in the last few decades to centuries, which is not been detected to date? How does the detection of movement of boulders help in understanding the recent activities? In this presentation, I will provide evidence for recent boulder falls and their hotspot regions on the Moon related to seismic activity/moonquakes, impact-generated surface shaking, and thermal weathering. Aside from very recent impacts, the primary activity observed on the Moon over the past few decades to centuries is the boulder falls. With the newly identified boulder falls, the Moon joins Earth and Mars, with records of recent boulder falls driven by multiple sources suggesting a sporadically active Moon. Such regions could be potential landing sites for future missions to understand the recent surface/subsurface activity on the Moon.
Probing Parent Body Processing Through the Spectral Signatures of Insoluble Organic Matter in CM Chondrites
Abstract
CM carbonaceous chondrites are time capsules preserving a complex history of aqueous alteration and thermal processing on their parent bodies. In this seminar, I will discuss how spectroscopic analysisof insoluble organic matter (IOM) from a wide suite of chondrites reveals temperatures (35–90°C) and duration of alteration. The variation in our estimates point towards multiple generations of organic matter, reflecting heterogeneity in parent body processes. Interestingly, some samples point to brief alteration events, while others hint at complex histories involving larger parent bodies or rubble-pile assemblies. These findings allow us to better understand the conditions under which primitive organic matter evolved in early solar system bodies.
The Role of Deformed Craters in Understanding Fault Kinematics and Geometries
Abstract
Understanding subsurface faults is inherently challenging, especially on planetary bodies where direct field observations are not possible. Numerous studies have relied on high-resolution imaging, topographic data, and numerical simulations to analyze surface features such as wrinkle ridges and lobate scarps, which are expressions of underlying thrust faults on the Moon, Mars, and Mercury. These surface morphologies reflect a range of fault geometries, including buckle folds, fault-bend folds, and backthrusts, though no consensus exists on their exact subsurface structures. Fault-controlled deformed craters—impact craters modified by fault movement—offer an alternative means of inferring fault orientation, displacement, and dip. Prior studies have used crater wall exposures and rim circularity to estimate fault parameters, but these approaches face limitations when traces are confined to crater walls or when craters are circular. To address this, we developed a method that applies to both crater walls and floors and accommodates various crater shapes. In my talk, I will present the methodology and results in detail.
Mineralogical Characterization of Mare Australe: A Unique Region on the Moon
Abstract
Mare Australe (47.77°S, 91.99°E) is a volcanic province ~1000 km in diameter at the eastern nearside and farside boundary of the Moon. It consists of 248 mapped basaltic patches arranged in a more-or-less circular pattern. Initially classified as a “distinct” basin, it was later considered a “no topographic basin” due to a lack of identifiable topographic features. The results from the GRAIL mission, did not confirm the presence of a basin coinciding with the previously proposed one. Instead, GRAIL suggested the presence of a ~880 km diameter impact structure northwards named the Australe North Basin centered at 35.5°S, 96°E. In the earlier study geological evidences were provided to further establish the presence of the Australe North Basin. Volcanic activity at Lacus Solitudinis and Bowditch Crater, once thought to be isolated, is now linked to Australe North Basin. Based on the re-defined basin boundaries in the region a significant part of Mare Australe’s basalts lie outside the boundaries of Australe North. These basaltic units of Mare Australe remain largely uncharacterized. In this seminar, I will present a detailed investigation into the mineralogical diversity of the Mare Australe region. This study aims to shed light on the nature and origin of the distinctive style of volcanism in the region, highlighting the unique geological setting of Mare Australe and its implications for lunar volcanic evolution.
Atmosphere Characterization of the Hot-Jupiter Exoplanets
Abstract
Hot Jupiters, tidally locked to their host stars, exhibit extreme day–night temperature contrasts that drive vigorous atmospheric circulation. In my recent work, I analytically and numerically quantified how this heat redistribution shapes their temperature–pressure (T–P) profiles and dayside emission spectra. Using discrete space theory radiative transfer simulations, I demonstrated that reduced heat redistribution leads to hotter daysides, stronger thermal inversions, and higher emission fluxes. Application to exoplanet XO-1b revealed near-complete heat redistribution, resolving key degeneracies in its atmospheric characterization. Beyond circulation, my research also addresses two crucial aspects:
• Radius Inflation: Ionized atmospheric flows coupled with magnetic fields generate Ohmic dissipation within the radiative and convective zones. MESA evolutionary simulations, parameterized by atmospheric flow velocities, successfully reproduce the observed inflated radii of hot Jupiters through this internal heating mechanism.
• Spectral Separation: I have generalized Chandrasekhar’s diffuse reflection theory to unify thermal emission and scattering, allowing precise separation of planetary spectra from stellar contamination in ultra-hot Jupiters.
In future work, I plan to integrate equilibrium and non-equilibrium chemistry into circulation models to better capture day–night variations in chemical abundances to study the effect of atmospheric heat redistribution on the atmospheric chemistry and finally its imprints on the emission spectra. Additionally, I aim to extend these frameworks to lower-mass, potentially habitable tidally locked terrestrial planets to inform climate and habitability studies. I also plan to develop improved radiative transfer tools that can simultaneously handle complex emission, scattering, and chemical processes, providing stronger predictive power for upcoming JWST and ARIEL observations.
Towards understanding lunar hydration using Chandrayaan-1 and Chandrayaan-2 NIR spectrometers
Abstract
The Moon Mineralogy Mapper (M3) onboard Chandrayaan-1 has been extensively utilized to map the global surface
composition and detect OH/H2O on the lunar surface. It was the first instrument to systematically detect and map the
3-µm absorption feature associated with hydration, using observations acquired at different times of the lunar day.
However, the compositional dependencies and temporal variability of this feature, especially in the polar regions,
remain poorly understood. Moreover, M3’s limited spectral coverage—extending only up to 3.0 µm—restricted its
ability to fully characterize the hydration feature and to distinguish between OH and H2O. The Imaging InfraRed
Spectrometer (IIRS) onboard Chandrayaan-2 addresses this limitation by extending the spectral range to 5.0 µm,
thus enabling discrimination between OH and H2O signatures. However, IIRS data also come with certain limitations
that must be carefully understood before it can be reliably applied at the global scale. In this talk, I will present our i
ndependent methodology for processing IIRS data in parallel with M3, aimed at achieving cross-calibration and a
robust comparison of hydration features. We have selected multiple overlapping IIRS observations, including
well-characterized landing sites, and categorized them based on lunar local time to study diurnal variations.
After applying dark current subtraction, radiometric correction, and thermal emission modeling, the IIRS spectra
were geometrically aligned with M3 and corrected for topographic and photometric effects. I will share our
preliminary results, insights gained from the IIRS data processing workflow, and our outlook for integrating IIRS
and M3 data in a comprehensive global-scale analysis.
Cosmogenic Nuclides in Meteorites: Constraining Cosmic Ray Exposure and Terrestrial Ages
Abstract
Cosmogenic nuclides, produced by interactions between cosmic rays and meteoritic matter, are powerful tools for determining the cosmic ray exposure (CRE) ages and terrestrial residence times of meteorites. This talk will highlight the combined approach using Accelerator Mass Spectrometry (AMS) along with Noble Gas Mass Spectrometry (NGMS) to estimate both CRE and terrestrial ages. The talk will discuss how radionuclides such as ¹⁰Be, together with stable noble gases like ²¹Ne, help reconstruct the exposure history, shielding conditions, and delivery mechanisms of meteorites. These methods play a key role in understanding the journey of meteoroids from space to Earth and contribute toward developing robust AMS measurement protocols at PRL.
Concentrations of Hydrogenated, nitrogenated, & protonated sulfuric acid ions due to GCR (Galactic Cosmic Rays) impact ionization in lower atmosphere of Venus.
Abstract
Solar radiation interacting with the Venusian atmosphere produces two prominent ionization layers: V2 (~140 km) and V1 (~125 km). However, due to the high atmospheric density, only Galactic Cosmic Rays (GCRs) can penetrate into the deeper layers of the Venusian atmosphere. As cosmic ray air showers propagate through the Venusian atmosphere, they develop extensively until reaching a maximum, typically located between 60 and 70 km, below this altitude, the flux of secondary particles steadily declines due to their insufficient energy to sustain ionization. Previous studies have theorized the ion-pair production rates in this region with negligible focus on ionic species responsible.
This presentation will begin with a general overview of the Venusian atmosphere, followed by a concise explanation of the methodology and chemical model we have used to compute electron densities and ion concentrations for 74 ion species in this region. The talk will conclude with a discussion on of some of the dominant ions identified in the lower region, for example hydrated hydronium ions and hydrated ions of NO2-, CO3-.
Farside Volcanism on the Moon: A Remote Sensing Perspective
Abstract
Volcanism on the Moon is primarily manifested in the form of mare basalts, which cover ⁓17% of its surface. Mare basalts exhibit significant compositional diversity and are mainly concentrated within and adjacent to the large circular impact structures, and have a total volume estimated at ~107 km3. Interestingly, the distribution of mare basalts is highly asymmetric, whereby the nearside hosts extensive basaltic emplacements and the farside exhibits remarkably fewer mare basalts. In my talk, I will be providing a detailed account of how the understanding of this fundamental dichotomy has evolved from the first glimpse of the farside by Luna 3 in 1959 to present-day (with missions like Clementine, Lunar Prospector, LRO, Chandrayaan, Kaguya, GRAIL, Chang’e). Despite these advances, key questions remain unanswered on the nearside-farside dichotomy in volcanism. I will discuss the existing gaps in the knowledge and the objectives of my thesis. The talk will conclude with preliminary results based on morphological and chronological studies of the Freundlich-Sharonov Basin, one of my study areas on the farside of the Moon that exhibits evidence of mare emplacement.
Development of Readout Electronics for Plastic Scintillators Coupled with a Photomultiplier Tubes (PMTs) for a Hard X-ray Compton Polarimeter
Abstract
Photons preferentially undergo Compton scatter perpendicular to the plane of polarization, a property that enables the measurement of linear polarization in hard X-rays. A Compton polarimeter employs a low-Z scatterer to maximize the probability of Compton scattering. This central scatterer is surrounded by a high-Z absorber, which detects the azimuthal distribution of scattered photons. In such a configuration, the lowest photon energy at which polarization can be effectively measured is determined by the lower energy detection efficiency of the scatterer. The efficiency is, in turn, limited by the noise performance of the readout electronics.
In this seminar, I will present an overview of the design considerations of the Hard X-ray Compton Polarimeter, with a focus on the development of readout electronics for the scatterer, a plastic scintillator coupled with a PMT. I will also discuss the experiment setup to characterize its detection efficiency at lower energies, aiming to improve the polarimeter sensitivity.
Investigation of Organic Matter in Differentiated Meteorites: Unveiling Indigenous Origins and Impact Dynamics
Abstract
The nature of organic matter in meteorites provides insights into early solar system chemistry and the evolutionary histories of their parent bodies, reflecting processes from nucleosynthesis and dust formation to planetesimal and planetary development over the last 4.5 billion years. This talk provides an overview of the first detailed investigation into the nature and origin of insoluble organic matter (IOM) in aubrites, a rare class of differentiated meteorites. I will present a multitechnique analysis of IOM in aubrites and enstatite chondrites, aimed at understanding the extent of organic distribution within the protoplanetary disk and the physicochemical processes that offer essential clues to their parent body evolution.
In this seminar, I will discuss the spectroscopic analyses of the IOM in aubrites compared with chondrite IOM to understand the structural and molecular heterogeneity in different meteorite classes. Further I will be discussing the microscopic studies of these organics highlighting the different carbon morphologies present in aubrites. The results offer new insights into the complex evolutionary history of aubrite parent bodies and contribute to a broader understanding of organic matter preservation in differentiated planetary materials.
N-Body Integration Model for Dust Dynamics and Flux Estimation in Inner Solar System
Abstract
Interplanetary Dust Particles (IDPs), originating from the Asteroid Belt, Kuiper Belt, Oort Cloud, and comets, are fundamental to many Solar System phenomena such as Zodiacal Light and meteor showers. As these particles spiral inward toward the Sun, their orbits are altered by a complex interplay of gravitational and non-gravitational forces, leading to gradual perturbations in their orbital elements. The mathematical formulation of the force models, orbital perturbation equations, and their impact on dust evolution will be discussed. We utilize and analyse the N-body problem using Everhart’s RA15 version of the RADAU integrator, which is particularly well-suited for handling stiff orbital equations. I will be presenting results highlighting how Mean Motion Resonances (MMRs) facilitate the capture and long-term trapping of dust particles near planets which can alter dust trajectories. Additionally, methodologies for statistical estimation of dust flux on planetary surfaces by analysing the position of dust particles over time during their close encounters with planets will be discussed. The velocity distribution of impacting particles will also be examined to provide a more complete picture of dust-planet interactions.
Understanding evolution of cometary volatiles
Abstract
Understanding the evolution of volatiles on the surfaces and subsurfaces of comets is crucial to studying their thermal, chemical, and structural history. This talk will provide an overview of the key physical processes driving volatile sublimation on comets, including heat conduction, sublimation, and gas diffusion through porous subsurface material. I will then discuss previous models of cometary nuclei and comae, highlighting their limitations—such as neglecting long-term thermal evolution, relying on simplified geometries (spherical or quasi-3D), underutilizing recent spacecraft data, and lacking integration between nucleus and coma evolution. Addressing these gaps, my research focuses on developing a model that comprehensively links the cometary surface and subsurface with the cometary atmosphere to study volatile evolution. This includes implementing coupled thermophysical and sublimation modelling across realistic comet geometries to interpret cometary activity better and simulate volatile loss over time—particularly at larger heliocentric distances (>3 AU), where CO and CO₂ dominate over H₂O as primary drivers of activity.
Decoding Aqueous Alteration on Mars: Insights from Water/Rock (WR) ratios in Open and Closed Systems
Abstract
In this talk, I will discuss how water/rock (WR) ratios under open and closed system conditions shape secondary mineral formation on Mars. For this, I shall be analyzing the secondary minerals on both Martian meteorites and terrestrial analogues (Deccan basalts from the Kutch area), which will help in understanding the geochemical conditions responsible for such alteration processes that will offer fresh insights into past climates and alteration histories on Mars.
Investigating the Impact of Hydrogen on Lunar Neutron Leakage Flux
Abstract
The Moon's lack of a magnetic field and atmosphere exposes its surface to ionizing radiation, including the solar wind, solar energetic particles (SEPs), and galactic cosmic rays (GCRs). High-energy GCRs interact with the lunar surface, generating fast neutrons through nuclear reactions. These fast neutrons are moderated by collisions with the nuclei in the lunar soil and can leak out, acting as messengers of the soil’s composition. Studying the neutron leakage spectrum can reveal important information about the abundance of near-surface hydrogen.
In this seminar, I will discuss the production and moderation processes of neutrons within the lunar surface, followed by an explanation of how the leakage neutron flux depends on hydrogen and other elements.
Global Detection of Lunar Pyroclastic Deposits (LPDs)
Abstract
Lunar Pyroclastic Deposits (LPDs) are fine-grained, low-albedo, Fe-Ti-rich volcanic glass-dominated lithological units typically
associated with thin crust and extensional tectonic regimes on the Moon. These deposits are providing key insight into thermal
evolution and volatile inventory of the Moon. However, their remote detection remains challenging due to the spectral similarities
between volcanic glasses and Fe-bearing common lunar minerals (e.g., Olivine, Pyroxene, etc.) in the visible to near-infrared
(VIS-NIR) spectral range.
In this seminar, I will present a novel approach developed for remote detection of LPDs by incorporating morphological
understanding with the spectral analysis covering both the spectral parameters. I will present new global LPDs maps,
based on the Moon Mineralogy Mapper (M3) data of two different optical periods. The results will be validated by
comparing the global outcomes to already reported LPDs. The main outcome of this work is new detections. I will
present a few case studies on new detections and validation to confirm their pyroclastic origin. I will also discuss
the inferences and implications during this seminar.
The Role of Layered Minerals in the Origin of Life Insights from Planetary Analogue Terrestrial Geomaterials
Abstract
How did life begin? Researchers believe that certain minerals, especially clays, played a big role in this process. These minerals can hold onto organic molecules, help chemical reactions happen, and create safe spaces for early life to form. Since they exist on Earth and other planets, they also help us search for signs of life beyond our planet. These layered minerals, abundant in terrestrial and extraterrestrial environments, serve as key indicators of fluid-rock interactions and potential biosignature preservation.
This talk will explore how clays can serve as one of the potential planetary analogue terrestrial geomaterials that can enhance our understanding of life’s emergence. By employing comprehensive biogeochemical fingerprinting, this research will characterize clay minerals in terrestrial settings, assessing their capacity to preserve biosignatures. By studying layered minerals on Earth and extending these findings to available extraterrestrial samples, we can unveil the largely unexplored role of clay minerals in the origin of life, which is essential for planning future astrobiological missions.
A Monte Carlo Approach to Temperature and Spectral Energy Distribution in Protoplanetary Disks
Abstract
A protoplanetary disk is a rotating circumstellar disk of dense gas and dust surrounding a young star. Understanding the structure and composition of these disks is essential for understanding the processes involved in planet formation. Over the years, various models have been developed to describe the chemical and hydrodynamic processes occurring within these disks. Here, we introduce a Monte Carlo Radiative Transfer (MCRT) model to characterize the temperature distribution and spectral energy throughout the disk and its surrounding envelope. MCRT method provides an efficient means of achieving radiative equilibrium without iteration in systems with temperature-independent opacity sources.
Additionally, the computational time required for this method is comparable to that of pure scattering models. The MCRT approach tracks individual photon packets, allowing for precise identification of energy absorption sites and subsequent adjustments to local cell temperatures. To enforce radiative equilibrium, each absorbed packet is instantly re-emitted, with its frequency selected to correct the cell’s thermal spectrum. These re-emitted packets can undergo scattering, absorption, and re-emission processes until they escape, enabling the system’s temperature and spectral energy distribution (SED) to reach equilibrium. We present the initial results of the simulations for both spherical symmetry models and 2D axisymmetric density structures, comparing the findings with standard benchmark tests.
Identification of Whistler Waves Near Flux Ropes in the Nightside Magnetosphere of Venus
Abstract
Whistler waves are electromagnetic plasma waves which are generated by temperature anisotropy instability in magnetized plasma. These right-handed circularly polarized waves propagate along the ambient magnetic field in a magnetized plasma. Atmospheric lightning has been considered a natural source of whistler waves at Venus. Recent observations from the Parker Solar Probe (PSP) during its fourth Venus Gravity Assist (VGA) detected whistler wave bursts in the Venusian magnetotail, with further analysis indicating a non-planetary origin. Magnetic reconnection, a fundamental plasma process which may be responsible for atmospheric erosion and dynamic magnetic activity in Venus' induced magnetosphere, emerges as a potential candidate. Observations at Earth have detected whistler waves near magnetic reconnection regions. Venus Express observed magnetic flux rope structures, which are formed by reconnection in Venus' magnetotail. This study explores the detection of whistler waves in the vicinity of these flux rope structures, bridging the concept of whistler wave generation via magnetic reconnection at Venus.
Electrostatic Dust Detachment
Abstract
The electrostatic processes are fundamentally important in understanding particle dynamics and the complex dusty plasma environment over the Moon. While many studies have examined dust levitation, the detachment of dust from the lunar surface remains a key factor in understanding the lunar dusty plasma environment. Dust particles on the charged lunar surface experience gravity, cohesion, and electrostatic forces. Typically, the electrostatic force derived from a uniformly charged surface (from Gauss Law) is insufficient to lift the particles against gravity. In this presentation, I will demonstrate that sufficient electric field and coulomb repulsion can be created between the dust and surface due to charge fluctuations on a microscopic scale, which can detach the dust particle from the lunar surface, overcoming dust-surface adhesive force.
Unravelling Mar’s Magmatic Past: Insights from Martian Shergottites
Abstract
Shergottites, constituting around 90% of the Martian meteorite collection, are categorized into various types: basaltic, olivine-phyric, poikilitic, and gabbroic. Notably, poikilitic shergottites are distinct from the other shergottites as they are cumulate and form at the deep interior into the Mars in comparison to the other extrusive members. This study delves into the mineralogy and petrology of a poikilitic shergottite, NWA 1950 to constrain Martian igneous processes and identify mantle source reservoirs for shergottites. Additionally, the olivine-hosted melt inclusions help to constrain parental melt compositions, mantle sources, and formation processes, while also reconstructing magma evolution from emplacement to ascent.
Identification and Characterization of Topside V3 Layer of Venusian Ionosphere
Abstract
The dayside Venusian ionosphere is produced by photoionization (primary) and photoelectron impact (secondary) ionization from solar EUV (10-105 nm) and SXR (0.1-10 nm) radiations producing V2 (~140 km) and V1 (~125 km) layers. Previous observations from missions such as the Mariner, Venera, and Pioneer Venus Orbiter also reported a "bulge" at 160–200 km altitudes. This bulge has not been documented in any of the standard ionospheric model. Moreover, there have been a limited data of the ionospheric observation during low solar activity which further constrain the characterization of this V3 layer. Using electron density profiles observed by VeRa radio occultation experiment under varying solar activity levels and solar zenith angles (SZAs), we examined the bulge, known as the "V3 layer". Our study analyzed over 200 electron density profiles to characterize this V3 layer. In this seminar I will briefly summarize the results of V3 layer morphology and occurrence rate under varying Solar activity and SZA conditions.
Tides as a tool for deciphering internal structures of telluric planets
Abstract
Modelling the tidal deformations observed on the telluric planets is a complementary approach to any seismological data to decipher their internal structure. It provides constraints on internal heterogeneities, as well as rheological and density constraints on materials, enabling tidal 'tomography'. These constraints, coupled with thermodynamic models, allow us to establish the current structure of these objects and help us to understand their geodynamic evolution. In this seminar, we will look at the internal structures of Moon and Mars cores, the process of mantle overturn during the crystallisation of the lunar magma ocean, the persistence of a potentially molten zone in the Martian mantle and the persistence of a significant viscosity contrast between the upper mantle of Venus and the lower mantle. We will also look at the viscosity contrasts between the Martian lithosphere and asthenosphere. The challenges of characterising the existence of heterogeinities in the Moon mantle will be also addressed.
Design and development of PRATHIMA electronics subsystem for LuPEX/Chandrayaan-5 Rover
Abstract
Permittivity and Thermophysical Instrument for Moon’s Aquatic Scout (PRATHIMA) is an instrument onboard ISRO-JAXA LuPEX Rover. PRATHIMA experiment consists of three main sub-systems: (a) a permittivity probe that will be deployed into ~50 cm of the lunar surface (in a pre-drilled borehole), (b) electronics and (3) a deployment mechanism. The Probe consists of pairs of electrodes, which consist of a pair of transmitters and receivers. The complex permittivity of the Lunar Regolith over the low-frequency range (e.g. 1Hz-10 kHz) by measuring the mutual impedance between the transmitter and receiver electrodes. The subsurface complex permittivity (i.e., dielectric constant and conductivity) is derived from the measured phase and amplitude of the mutual impedance. The dielectric constant of water ice embedded in Lunar regolith strongly depends on the frequency in the 10 Hz-10 KHz range and temperature. The design aspects and its development status will be presented in the seminar.
Transmitter electronics of Permittivity and Thermophysical Instrument for Moon’s Aquatic Scout (PRATHIMA)
Abstract
PRATHIMA is one of the selected payloads for the LUPEX/Chandrayaan-5 mission. Its primary objective is to detect and quantify regolith-bound water-ice on the lunar surface/subsurface in the vicinity of the landing site, along the traverse of the rover. The working principle of PRATHIMA involves measuring the dielectric permittivity of water-ice at low frequencies, as water-ice exhibits a significantly high dielectric permittivity in this range. Therefore, a low-frequency sinusoidal signal can be used to excite a medium to study the presence of water-ice content mixed with the regolith.A transmitter electronics system has been designed to generate a programmable low-frequency sinusoidal signal using an FPGA-based Direct Digital Synthesis (DDS) algorithm.
Characterization of Multichannel SDD X-Ray Spectrometer with ASIC Readout
Abstract
In the seminar, I will present the development of a multichannel Silicon Drift Detector (SDD) based X-ray spectrometer with application-specific integrated circuit (ASIC) readout aimed at flying in future space missions. The multiple channels facilitate the spectrometer to have a large detection area, allowing the detection of faint X-ray sources. The spectrometer is designed to readout the signal from eight SDDs through a VErsatile Readout for Detector
Integration (VERDI) ASIC with high energy resolution in the 1-25 keV energy range. The spectrometer provides an X-ray spectrum for each detector simultaneously. Initially, the system is tested with five SDDs and shown that the spectrometer provides the energy resolution of ~148 eV at 5.9 KeV when SDDs are cooled to -35oC. We have also assessed the system’s performance for different detector operating temperatures and pulse shaping times. The detailed design and the performance assessment of the spectrometer will be presented in the seminar.
The Origin of Isotopes
Abstract
The origin of isotopes plays a cruicial role in understanding the chemical enrichment of the Universe. Isotopes are formed through nucleosynthesis processes in stars, including stellar burning, supernovae, and neutron star mergers. These processes distribute isotopes into the interstellar medium (ISM), influencing the evolution of galaxies. Galactic Chemical Evolution (GCE) provides a framework to model the production, distribution, and recycling of isotopes over cosmic time, driven by processes such as star formation, stellar feedback, and gas inflow/outflow.
In this seminar, I will discuss the primary sources of isotopes, the physics of their nucleosynthesis, and the mechanisms by which they are transported and mixed within galaxies. The talk will also explore the connection between isotope studies and the broader understanding of the Milky Way's formation and evolution.
A 3D Thermophysical model for Temperatures and Thermophysics at Prospective Sites on Mars
Abstract
Existing thermal models of Mars, such as the KRC 1D model, lack the ability to account for complex heat transport processes, topographical variations, and environmental factors like dust storms and surface changes. This study addresses these gaps by developing a 3D thermophysical model that integrates lateral heat transport, accurate topography from MOLA DEM, and Martian-specific conditions, including its thin CO₂ atmosphere and thermal inertia. The model provides detailed insights into localized thermal variations at prospective landing sites, enhancing mission planning and advancing our understanding of Mars' thermal behavior and geological history.
Mathematical Framework for Dust Dynamics under Different Forces
Abstract
Interplanetary Dust Particles (IDPs) are a fundamental constituent of the Solar System, originating from diverse sources such as the Asteroid Belt, Kuiper Belt, Oort Cloud, and comets. It manifests in phenomena like Zodiacal Light and Meteor showers. As IDPs migrate inward toward the Sun, their dynamics are governed by a combination of gravitational and non-gravitational forces, including Poynting-Robertson drag, solar radiation pressure, and solar wind drag, which induce perturbations in their orbital elements. In this seminar, I will discuss the mathematical framework for orbital perturbations and the governing force equations, derived from the principles of celestial mechanics. The variation in orbital elements due to the governing forces will be analyzed, along with the obtained results. In addition to this, the method for estimating the dust flux on planetary bodies will be explored, with a focus on insights derived from our research.