About

Pranabendu Moitra is an Assistant Professor at the University of Arizona, having joined the faculty in 2023. He earned his Ph.D. in Earth Science from Rice University, Texas. His professional contact is pmoitra@arizona.edu. The information provided does not include specific details about his research focus, background beyond his degree, or key contributions. Therefore, a detailed professional biography summarizing his research interests or accomplishments cannot be generated from the available text.

Research topics

• Geology
• Geochemistry
• Thermodynamics
• Geophysics
• Physics
• Materials science
• Paleontology
• Astrobiology
• Meteorology
• Petrology
• Earth science

Selected publications

• Thin H ₂ -dominated Atmospheres as Signposts of Magmatic Outgassing on Tidally Heated Terrestrial Exoplanets

  The Planetary Science Journal · 2026-04-01

  articleOpen access

  Abstract H 2 -dominated terrestrial exoplanets are highly accessible to atmospheric characterization via transmission spectroscopy, but such atmospheres are generally thought to be unstable to escape. Here, we propose that close-in, eccentric terrestrial exoplanets can sustain H 2 -dominated atmospheres due to intense tidally driven volcanic degassing. We develop an interior–atmosphere framework to assess whether volcanic outgassing can sustain H 2 -dominated atmospheres over geologic timescales (≥1 Gyr). We incorporate interior redox state, tidal heating, volatile inventory, and planetary parameters to compute outgassing fluxes and confront them with energy-limited hydrodynamic escape. We demonstrate that to sustain an H 2 -dominated atmosphere, a terrestrial exoplanet must have a water-rich mantle and reduced melt, in addition to high eccentricity. We additionally demonstrate that detection of a specifically thin H 2 -dominated atmosphere is a sign of current magmatic outgassing. We delineate an “outgassing zone” (OZ) most favorable to the existence of such planets, and identify the most observationally compelling targets. We propose combining precise mass–radius–eccentricity measurements with JWST constraints on atmospheric mean molecular mass μ to search for thin H 2 -dominated atmospheres. Inversely, we argue that robust atmospheric nondetections on OZ exoplanets can constrain the planetary interior, including melt redox state, mantle melt fraction, volatile inventory, and tidal heat flux.

  PublisherDOI

• Geometric phase sensing using seismic waves: A new tool for comprehensive volcano monitoring at Kilauea, Hawaii

  Zenodo (CERN European Organization for Nuclear Research) · 2026-05-15

  otherOpen access

  No description provided.

  PublisherDOI

• Geometric phase sensing using seismic waves: A new tool for comprehensive volcano monitoring at Kilauea, Hawaii

  Open MIND · 2026-05-15

  otherOpen access

  No description provided.

  PublisherDOI

• Trace element analyses of plagioclase from troctolite 76535 and implications for the petrogenesis of the lunar highlands Mg‐suite

  Meteoritics and Planetary Science · 2025-09-09

  article

  Abstract We used trace element analyses of plagioclase from Mg‐suite troctolite 76535 to estimate the Rare Earth Element (REE) concentrations of its parental liquid and assess the feasibility of an urKREEP contribution to the Mg‐suite parental liquid. We measured 33 trace elements in 76535 plagioclase separates. Our measurements revealed enrichments in incompatible elements consistent with previous analyses. Using the measured REE concentrations, we estimated the REE concentrations of the unfractionated Mg‐suite parental liquid using a RhyoliteMELTS‐based forward model. Compared to chondritic concentrations, the Mg‐suite parental liquid is ~100 times more enriched in light REEs and ~10 times more enriched in heavy REEs. We sought to explore the feasibility of reproducing these enrichments in the parental liquid through assimilation of urKREEP by a partial melt of rising LMO cumulates during cumulate mantle overturn. We show that these enrichments can be reproduced by a 30%–50% addition of fully molten urKREEP to the LMO cumulate melt, if the LMO cumulate melt and urKREEP are in thermal equilibrium with each other. However, the Mg# of these mixtures (57–68) is too low to produce the most Mg‐rich olivine (Fo 91) observed in Mg‐suite troctolites. Alternatively, assuming that the LMO cumulate melt and urKREEP are in thermal disequilibrium, we reproduced both the REE abundances and Mg# of the Mg‐suite parental liquid with only a 10% addition of the urKREEP partial melt. These results support the feasibility of urKREEP assimilation as a mechanism for generating the incompatible element enrichments in Mg‐suite magmas while preserving their major element chemistry.

  PublisherDOI

• Trace Element Analyses of Plagioclase from Troctolite 76535 and Implications for Mg-suite Petrogenesis

  2025-01-21

  preprint

  Certain Mg-suite samples display enrichment in incompatible elements, likely resulting from the assimilation of the material that crystallized at the very late stages of magma ocean (ur-KREEP). This study uses trace element analyses of plagioclase separates from sample 76535 to estimate the Rare Earth Element (REE) concentration of the Mg-suite parental liquid and assess the extent of contribution from ur-KREEP. Thirty-three trace elements, including REEs, were measured in the separates and the measured REEs reflect magmatic conditions being free from subsolidus alteration. The Mg-suite parental liquid was estimated using these REE data as targets for a Python-based forward model which employs a RhyoliteMELTS-defined liquid line of descent. The estimated parental liquid shows REE enrichments of 200 times chondritic levels for Light REEs and 20 times for Heavy REEs. Mixing models between the REE compositions of a potential Mg-suite primary liquid and modeled ur-KREEP indicate that 30-50% assimilation of ur-KREEP is required to reproduce the observed REE concentrations in the Mg-suite parental liquid. We demonstrate an approach to determine the petrogenesis of a sample by characterizing a very limited quantity of grains, in an effort to maximize the scientific output from current and future returned samples such as Artemis.

  PublisherDOI

• Flow‐ and Fracture‐Driven Bubble Throat Growth Rates and Dynamic Permeability in Crystallizing Magma

  Geochemistry Geophysics Geosystems · 2025-01-30 · 5 citations

  articleOpen access1st authorCorresponding

  Abstract Pyroclasts typically exhibit coalesced vesicle textures, which are the evidence of bubble coalescence and the incomplete bubble wall retraction in magma during volcanic eruptions. The sizes of bubble throats or inter‐bubble apertures in permeable networks control the extent of magma outgassing, and therefore, quantifying the growth rates of the bubble throats is important but has remained poorly constrained. Using dynamically similar experiments with spontaneous bursting of a single bubble in rheologically well‐characterized particulate suspensions, we investigate the growth rate of bubble throats for a range of particle volume fractions. For suspensions with 0.50 particle volume fraction, a circular hole (bubble throat) forms following bubble bursting, which after an initial fast growth starts plateauing at a throat‐bubble size ratio of 0.20. The throat growth time scale overall increases with increasing particle volume fraction due to the increase in suspension viscosity. On the other hand, bubbles in suspensions with particle volume fraction near the maximum packing fraction (0.64) exhibit a fracture‐like opening. Thus, our experimental results suggest that the plateauing of the bubble throat growth in crystal‐poor to crystal‐rich magma likely contributes to the wide occurrence of the incompletely retracted vesicle walls in pyroclasts. The implications of the flow‐ to fracture‐like growth of bubble throats on the development of dynamic permeability in magma are discussed.

  PublisherOA PDFDOI

• Thin H$_2$-dominated Atmospheres as Signposts of Magmatic Outgassing on Tidally-Heated Terrestrial Exoplanets

  ArXiv.org · 2025-10-08

  preprintOpen access

  H$_2$-dominated terrestrial exoplanets are highly accessible to atmospheric characterization via transmission spectroscopy, but such atmospheres are generally thought to be unstable to escape. Here, we propose that close-in, eccentric terrestrial exoplanets can sustain H$_2$-dominated atmospheres due to intense tidally-driven volcanic degassing. We develop an interior-atmosphere framework to assess whether volcanic outgassing can sustain \ch{H2}-dominated atmospheres over geologic timescales ($\geq$1 Gyr). We incorporate interior redox state, tidal heating, volatile inventory, and planetary parameters to compute outgassing fluxes and confront them with energy-limited hydrodynamic escape. We demonstrate that to sustain an H$_2$-dominated atmosphere, a terrestrial exoplanet must have a water-rich basal magma ocean and reduced melts, in addition to high eccentricity. We additionally demonstrate that detection of a specifically thin H$_2$-dominated atmosphere is a sign of current magmatic outgassing. We delineate an "outgassing zone" (OZ) most favorable to the existence of such planets, and identify the most observationally compelling targets. We propose combining precise mass-radius-eccentricity measurements with JWST constraints on atmospheric mean molecular mass $μ$ to search for thin H$_2$-dominated atmospheres. Inversely, we argue that robust atmospheric non-detections on OZ exoplanets can constrain the planetary interior, including melt redox state, mantle melt fraction and volatile inventory, and tidal heat flux.

  PublisherOA PDFDOI

• Rheological arrest vs. rapid growth of bubbles in crystal-rich magma

  Earth and Planetary Science Letters · 2024-09-10 · 4 citations

  article1st authorCorresponding
  PublisherDOI

• Water Release during Lunar Magma Ocean Crystallization and the Potential Endogeneous Origin of Water-Ice in the Permanently Shadowed Regions of the Moon

  2024-07-03

  preprintOpen access

  Introduction:The detection of trapped water ice in permanently shadowed regions of the Moon [1] is of interest for water harvesting to support life and generate fuel [2, 3]. The origins of the cold trapped water ice are debated and affect the distribution and abundance of ice, the knowledge of which is required for water harvesting [4]. Here we investigate a previously unexplored possibility that some fraction of the cold trapped water ice may have originated from lunar magma ocean (LMO) outgassing. Using H2-H2O solubility laws and thermodynamic modeling of coupled degassing and crystallization, we provide estimates on the range of water masses that might have been outgassed during LMO crystallization.Methods: We model LMO crystallization using the softwares SPICEs [5] and alphaMELTS [6] which have been successfully employed in recent studies [7, 8, 9]. The estimated mass of water outgassed during LMO crystallization depends on the initial bulk H2O content of the LMO, the partition coefficients of H2O between minerals crystallized from the LMO and LMO melt, the initial LMO depth, and the fraction of interstitial liquid trapped during LMO crystallization [8, 9]. The bulk H2O content of the LMO and the partition coefficients of H2O (for relevant LMO minerals and conditions) are currently poorly constrained [e.g. 8, 9, 10]. Using the measured H2O content in plagioclase from ferroan anorthosites (FAN) [11] as the observational constraint to validate their models, [8, 9] demonstrated that the model outputs are not sensitive to either the fractions of trapped interstitial liquid or the initial LMO depth. Accordingly, an initial LMO depth of 600 km and 0% interstitial liquid are considered in this study. We vary the initial bulk LMO H2O from 1-5000 ppm and the partition coefficients between the maximum and minimum values reported in the literature. We consider two species of hydrogen dissolved and eventually outgassed from the LMO: H2O and H2. Their proportions depend on the fO2 of the system, which we varied from IW to IW-2 [12]. We use the solubility laws of [13] and [14] to model water outgassing during LMO crystallization. By integrating volatile exsolution over depth, the total amount of degassed volatiles from the LMO at a given temperature is calculated. We consider that the vigor of convection in the LMO affects the outgassing efficiency by varying the number of degassing cycles (1-50) per cooling step during crystallization and assess the effect on our model results. We bracket the range of realistic LMO crystallization scenarios based on the conditions required to explain the H2O in FAN plagioclase, calculate the total H2O mass released under such conditions, and compare it with the polar ice inventory.Results and Discussion: We find that when the mineral-melt partition coefficient of H2O approaches the minimum (Dmin), the number of degassing cycles (i.e. the contribution of LMO convection to outgassing efficiency) has no effect when bulk H2O ≤ 100 ppm, but is important at higher bulk H2O contents. The H2O contents in crustal plagioclase are best explained by bulk H2O contents ≥ 100 ppm. For Dmax the amount of H2O degassed in each cycle is small, hence, the crustal H2O is not very sensitive to degassing cycles. However, only drier LMO (≤ 10 ppm bulk H2O) can explain the crustal H2O contents. Accordingly, we provide estimates of the total amount of H2O released during LMO crystallization for ≥ 100 ppm bulk H2O, 1-50 degassing cycles/K for Dmin, and ≤ 10 ppm and only 50 degassing cycles/K for Dmax. For Dmin, the outgassed H2O ranges from 1016-1021 kg (up to 7 orders of magnitude higher than mare volcanic H2O outgassing estimates of ~1014 kg [15] and 1016 kg [16, 17]), and the outgassed H2 ranges from 1015-1020 kg. For Dmax, the outgassed H2O ranges from 103-104 kg, and the outgassed H2 ranges from 1012-1013 kg. We find that the species and mass of outgassed volatiles are very sensitive to the mineral-melt partition coefficient of H2O, which emphasizes the need to determine these partition coefficients specifically for lunar conditions in future studies. For Dmin, if the outgassed H2 does not oxidize to H2O and only the outgassed H2O contributes to water-ice,

  PublisherDOI

• Vapor bubbles and velocity control on the cooling rates of lava and pyroclasts during submarine eruptions

  Zenodo (CERN European Organization for Nuclear Research) · 2022-07-14

  datasetOpen access1st authorCorresponding

  These dataset contains videos (.mp4) of experiments and the time-temperature data (.txt) measured during the experiments. Each video starts when the sample is completely submerged in the water. The temperature data represents the full experimental duration, where a spike in water temperature data to about 27 deg C on average indicates the synchronization process between the video and the data.

  PublisherDOI

Recent grants

• Collaborative Research: Experimental constraints on the solidification time scales and fragmentation of submarine lava flows

  NSF · $380k · 2021–2026

Frequent coauthors

• Ingo Sonder

  University at Buffalo, State University of New York

  18 shared

• D. G. Horvath

  Planetary Science Institute

  16 shared

• J. C. Andrews‐Hanna

  Planetary Science Institute

  14 shared

• Greg A. Valentine

  University at Buffalo, State University of New York

  12 shared

• Helge Torgersen

  Rice University

  11 shared

• B. F. Houghton

  University of Hawaii System

  9 shared

• C. W. Hamilton

  University of Arizona

  4 shared

• Chandra Sekhar Tiwary

  4 shared

Labs

• Moitra LabPI

Education

• PhD, Earth Science

  Rice University

  2015