About

Steve Desch is a professor of astrophysics in the School of Earth and Space Exploration at ASU. His research focuses on developing models of star and planet formation, using data from meteoritics and planetary science. He especially studies the origins of chondrules and meteorites. He also works in the fields of exoplanets and astrobiology and is Principal Investigator of the NASA-funded NExSS grant to study geochemical cycles on exoplanets to aid searches for signs of life on other planets. He has modeled small icy bodies to explore the likelihood of subsurface water on Pluto and its moon, Charon, the asteroid Ceres, and others. Additionally, he has recently advocated the concept of Arctic Ice Management, to study how to increase sea ice in the Arctic in response to climate change. Asteroid 9926 Desch is named after him.

Research topics

• Computer Science
• Astrobiology
• Geology
• Physics
• Social Science
• Computer Security
• Sociology
• Paleontology
• Geochemistry
• Biology
• Astronomy
• Data science
• Earth science

Selected publications

• Petrographic, Geochemical, Isotopic, and Noble Gas Characterization of NWA 8409

  Zenodo (CERN European Organization for Nuclear Research) · 2026-01-01

  articleOpen access

  Stephant, A., Desch, S. J., Anand, M., Zhao, X., Cuppone, T., Rider-Stokes, B. G., Carli, C., Gamblin, J., Füri, E., Nottingham, M., Pratesi, G., & Franchi, I. A. (2026). Exploring nebular ingassing in the inner Solar System: evidence from the unique achondrite NWA 8409. Advances in Geochemistry and Cosmochemistry, 2(1), 764. https://doi.org/10.33063/agc.v2i1.764 This dataset presents the Petrographic, Geochemical, Isotopic, and Noble Gas Characterization of NWA 8409 1: NanoSIMS raw and treated data for H2O estimations and D/H ratio in pyroxenes of NWA 8409. NanoSIMS raw and background-corrected data used for estimating H₂O concentrations and D/H ratios in pyroxenes from NWA 8409. Measurements were performed using a Cameca NanoSIMS 50L at The Open University. Reported values include secondary ion intensities (H⁻, D⁻, ¹⁶O⁻), calculated H₂O contents, δD values, associated uncertainties (2σ), and corrections applied for instrumental mass fractionation, analytical background, and cosmogenic spallation 2: Literature data for H2O and dD in NAMs of achondrites and bulk/ice of chondrites compilation of literature H₂O contents and hydrogen isotopic compositions (δD) of nominally anhydrous minerals (NAMs) from achondrites, together with bulk and ice compositions of chondrites. No new analyses were performed for this table; data are reproduced from published sources to provide a comparative framework for evaluating the volatile inventory and isotopic signatures of NWA 8409 relative to other inner Solar System materials. 3: Bibliography of listed references from page 2 4: Noble gases Noble gas abundances and isotopic ratios (Ne and Ar) measured in bulk fragments of NWA 8409 using a NoblesseHR noble gas mass spectrometer at the noble gas facility of the Centre de Recherches Pétrographiques et Géochimiques (CRPG, France), following CO₂ laser extraction. Data include isotopic ratios, elemental concentrations, blank corrections, and analytical uncertainties, and constrain cosmic-ray exposure effects. 5: ICPMS bulk and trace elements for NWA 8409 (this study) and paired meteorites (literature) Bulk major and trace element compositions of NWA 8409 determined in this study by inductively coupled plasma mass spectrometry (ICP-MS) and inductively coupled plasma optical emission spectroscopy (ICP-OES) at the Department of Earth Sciences, University of Firenze, together with published data for paired samples from the literature. These data are used to assess geochemical variability, pairing relationships. 6: Mineralogy of NWA 8409 Modal mineralogy and mineral chemical compositions of NWA 8409 derived from scanning electron microscopy with energy-dispersive spectroscopy (SEM-EDS; ZEISS EVO MA 15), electron back-scatter diffraction (EBSD; Oxford Instruments Symmetry 2 detector), and focused ion beam–SEM (Zeiss Crossbeam 550). These observations document the textural context of the analyzed phases and underpin interpretations of petrogenesis and thermal history.

  PublisherDOI

• Petrographic, Geochemical, Isotopic, and Noble Gas Characterization of NWA 8409

  Open MIND · 2026-01-01

  article

  This dataset presents the Petrographic, Geochemical, Isotopic, and Noble Gas Characterization of NWA 8409 1: NanoSIMS raw and treated data for H2O estimations and D/H ratio in pyroxenes of NWA 8409. NanoSIMS raw and background-corrected data used for estimating H₂O concentrations and D/H ratios in pyroxenes from NWA 8409. Measurements were performed using a Cameca NanoSIMS 50L at The Open University. Reported values include secondary ion intensities (H⁻, D⁻, ¹⁶O⁻), calculated H₂O contents, δD values, associated uncertainties (2σ), and corrections applied for instrumental mass fractionation, analytical background, and cosmogenic spallation 2: Literature data for H2O and dD in NAMs of achondrites and bulk/ice of chondrites compilation of literature H₂O contents and hydrogen isotopic compositions (δD) of nominally anhydrous minerals (NAMs) from achondrites, together with bulk and ice compositions of chondrites. No new analyses were performed for this table; data are reproduced from published sources to provide a comparative framework for evaluating the volatile inventory and isotopic signatures of NWA 8409 relative to other inner Solar System materials. 3: Bibliography of listed references from page 2 4: Noble gases Noble gas abundances and isotopic ratios (Ne and Ar) measured in bulk fragments of NWA 8409 using a NoblesseHR noble gas mass spectrometer at the noble gas facility of the Centre de Recherches Pétrographiques et Géochimiques (CRPG, France), following CO₂ laser extraction. Data include isotopic ratios, elemental concentrations, blank corrections, and analytical uncertainties, and constrain cosmic-ray exposure effects. 5: ICPMS bulk and trace elements for NWA 8409 (this study) and paired meteorites (literature) Bulk major and trace element compositions of NWA 8409 determined in this study by inductively coupled plasma mass spectrometry (ICP-MS) and inductively coupled plasma optical emission spectroscopy (ICP-OES) at the Department of Earth Sciences, University of Firenze, together with published data for paired samples from the literature. These data are used to assess geochemical variability, pairing relationships. 6: Mineralogy of NWA 8409 Modal mineralogy and mineral chemical compositions of NWA 8409 derived from scanning electron microscopy with energy-dispersive spectroscopy (SEM-EDS; ZEISS EVO MA 15), electron back-scatter diffraction (EBSD; Oxford Instruments Symmetry 2 detector), and focused ion beam–SEM (Zeiss Crossbeam 550). These observations document the textural context of the analyzed phases and underpin interpretations of petrogenesis and thermal history.

  DOI

• Orbital Chaos and Observational Consequences in Three-Body Stellar Systems (Alpha Centauri)

  2025-08-27

  preprintOpen access1st authorCorresponding

  The three-body problem, a foundational challenge in celestial mechanics, arises when predicting the motion of three gravitationally interacting bodies. Unlike the two-body case, which admits closed-form solutions under Newtonian mechanics, the three-body configuration yields nonlinear equations that are highly sensitive to initial conditions, leading to chaotic and often unpredictable orbital evolution. In this study, we focus on the Alpha Centauri system, a gravitationally bound triple-star arrangement located approximately 4.37 light-years from Earth. The system consists of two Sun-like stars, Alpha Centauri A (spectral type G2V) and Alpha Centauri B (spectral type K1V), orbiting each other in a highly elliptical binary, and Proxima Centauri (spectral type M5.5Ve), a red dwarf with a distant, weakly bound orbit. Using principles of orbital mechanics, gravitational dynamics, and radiative transfer, we investigate how the interplay of gravitational forces and stellar motion affects apparent luminosity from a fixed observational frame. Our results demonstrate that even in relatively well characterized stellar systems, orbital perturbations produce measurable variations in observed brightness, illustrating the inherently chaotic nature of multi-body gravitational systems. These findings are relevant for exoplanet detection, stability analyses, and the interpretation of photometric variability in nearby star systems.

  PublisherOA PDFDOI

• Applying Statistical Chronometry to Erg Chech 002

  2025-01-01

  article1st authorCorresponding
  PublisherDOI

• A Disintegrating Rocky World Shrouded in Dust and Gas: Mid-infrared Observations of K2-22 b Using JWST

  The Astrophysical Journal Letters · 2025-06-25 · 4 citations

  preprintOpen access

  Abstract The disintegrating ultrashort period rocky exoplanet K2-22 b periodically emits dusty clouds in a dynamically chaotic process resulting in a variable transit depth from 0% to 1.3%. The effluents that sublimate off the surface and condense out in space are probably representative of the formerly interior layers convectively transported to the molten surface. Transmission spectroscopy of these transiting clouds reveals spectral fingerprints of the interior composition of this rocky world. We used JWST’s Mid-Infrared Instrument as a low-resolution slitless spectrograph to observe four predicted transit windows for K2-22 b. For each observation, we extracted a transmission spectrum over the spectral range of 4.4–11.8 μ m. Over the spectral range of 4.4–8 μ m, where the spectral precision is highest, we detect one transit at high significance and two at low significance. While the signal-to-noise ratio of the spectrum limits our ability to draw firm conclusions, we find that the data (1) disfavor featureless, iron-dominated core material, (2) are consistent with some form of magnesium silicate minerals, likely from mantle material, and (3) show a distinct and unexpected feature at ∼5 μ m. The unexpected feature, also seen weakly in the low-significance transits, is consistent with an unknown gaseous absorber, possibly NO and/or CO 2 . These findings warrant further study to improve the constraints on the composition of this disintegrating rocky world.

  PublisherDOI

• Be,La,U-rich spherules as microtektites of terrestrial laterites: What goes up must come down

  arXiv (Cornell University) · 2024-03-08 · 1 citations

  preprintOpen access1st authorCorresponding

  Recently Loeb et al. (2024, "Recovery and Classification of Spherules from the Pacific Ocean Site of the CNEOS 2014 January 8 (IM1) Bolide", Res. Notes. Amer. Astron. Soc. 8, 39) reported the magnetic collection of millimeter-sized spherules from the seafloor near Papua New Guinea. About 22% had Mg/Si < 1/3 and were identified as a new "differentiated" variety of cosmic spherule ("D-type"). In a subset of 26 of these "D-type" spherules, 12 "BeLaU" spherules were found to be dominated by Fe and Al, marked by low Si and even lower Mg content, depletions of volatile species like Pb and Cs, and remarkable enrichments of Be, La, U, Ba, and other elements. Loeb et al. claimed these have exotic compositions different from other Solar System materials. We show that in fact samples with these compositions are not just found on Earth, they are from Earth; specifically, we identify them as microtektites of terrestrial lateritic sandstone. Based on the location of the sample site, we associate them with the Australasian tektite strewn field, generated 788 kyr ago by an impactor that melted and ejected ~10^8 tons of sandstone, including a lateritic layer, from Indochina. A tektite origin for the spherules is corroborated by their terrestrial Fe isotopic compositions and the compound, non-spherical nature of many of them, which preclude formation as ablation spherules from a bolide. Due to the restriction of laterites to the tropics, iron-rich tektites may be uncommon, but we predict they should comprise ~3% of the Australasian microtektites.

  PublisherOA PDFDOI

• No evidence for interstellar fireballs in the CNEOS database

  Astronomy and Astrophysics · 2024-09-21 · 14 citations

  articleOpen accessSenior author

  Context . The detection of interstellar meteors, especially meteorite-dropping meteoroids, would be transformative, as this would enable direct sampling of material from other stellar systems on Earth. One candidate is the fireball observed by U.S. government sensors on January 8, 2014. It has been claimed that fragments of this meteoroid have been recovered from the ocean floor near Papua New Guinea and that they support an extrasolar origin. Based on its parameters reported in the Center for Near Earth Object Studies (CNEOS) catalog, the fireball exhibits a hyperbolic excess velocity that indicates an interstellar origin; however, the catalog does not report parameter uncertainties. Aims . To achieve a clear confirmation of the fireball’s interstellar origin, we assessed the underlying error distributions of the catalog data. Our aim was also to confirm whether the fragments of this meteoroid survived passage through the atmosphere and assess all conditions needed to unambiguously determine the fragments’ origin. Methods . We approached the investigation of the entire catalog using statistical analyses and modeling, and we provide a comprehensive analysis of the individual hyperbolic CNEOS cases. Results . We have developed several independent arguments indicating substantial uncertainties in the velocity and radiant position of the CNEOS events. We determined that all the hyperbolic fireballs exhibit significant deviations from the majority of the events in one of their velocity components, and we show that such mismeasurements can produce spurious parameters. According to our estimation of the speed measurement uncertainty for the catalog, we found that it is highly probable that such a catalog containing only Sun-bound meteors would show at least one event that appears highly unlikely to be Sun-bound. We also establish that it is unlikely that any fragments from a fireball traveling at the high inferred velocities could survive passage through the atmosphere. When assuming a much lower velocity, some fragments of this meteoroid could survive; however, they would be of a common Solar System origin and thus highly probable to be indistinguishable from the quantity of other local micrometeorites that have gradually accumulated on the sea floor. Conclusions . We conclude that there is no evidence in the CNEOS data to confirm or reject the interstellar origin of any of the nominally hyperbolic fireballs in the CNEOS catalog. Therefore, the claim of an interstellar origin for the fireball recorded over Papua New Guinea in 2014 remains unsubstantiated. We have also gathered arguments that refute the claim that the collected spherules from the sea floor originated in the body of this fireball.

  PublisherOA PDFDOI

• Critique of arXiv submission 2308.15623, "Discovery of Spherules of Likely Extrasolar Composition in the Pacific Ocean Site of the CNEOS 2014-01-08 (IM1) Bolide", by A. Loeb et al

  arXiv (Cornell University) · 2023 · 1 citations

  1st authorCorresponding
  • Astrobiology
  • Geology
  • Geochemistry

  Recently a manuscript by Loeb et al. was uploaded to arXiv (preprint 2308.15623) that asserted that the CNEOS bolide 2014-01-08 was interstellar; that spherules recovered from the seafloor near the airburst were associated with this bolide; that they had Fe isotopic ratios indicating origin as micrometeorites; that they had unusual chemical compositions enriched in Be, La and U, never seen before in micrometeorite spherules; that these compositions were formed in the magma ocean stage of a differentiated extrasolar planet; and that the Be abundance reflected passage through the interstellar medium. Despite not being peer-reviewed, this uploaded manuscript has been reported by media outlets as "published", and its conclusions have been widely distributed as fact. The purpose of this manuscript is to provide potential peer reviewers and the general public with an appreciation of the multiple fatal flaws with the manuscript's arguments. We discuss the published evidence that the 2014-01-08 bolide is not interstellar. We show that there is no statistical spatial correlation of a chemical signature or even number of recovered spherules with the 2014-01-08 bolide. We demonstrate that the Fe isotopic ratios decisively indicate an origin in our Solar System, with > 99.995% probability. We demonstrate that the unusual enrichments in La, U, etc., have in fact been observed in micrometeorites before and attributed to terrestrial contamination; and that the Be abundances are similarly consistent with those of ferromanganese nodules, after reacting with sea water. Far from being exotic particles from an extrasolar planet, the spherules collected and analyzed by Loeb et al. appear to be just like those found around the world, with a Solar System origin and compositions modified by tens of thousands of years residence at the ocean bottom.

  PublisherOA PDFDOI

• Exogeoscience and Its Role in Characterizing Exoplanet Habitability and the Detectability of Life

  2021-03-18 · 1 citations

  preprintOpen access

  The search for exoplanetary life must encompass the complex geological processes reflected in an exoplanet's atmosphere, or we risk reporting false positive and false negative detections. To do this, we must nurture the nascent discipline of "exogeoscience" to fully integrate astronomers, astrophysicists, geoscientists, oceanographers, atmospheric chemists and biologists. Increased funding for interdisciplinary research programs, supporting existing and future multidisciplinary research nodes, and developing research incubators is key to transforming true exogeoscience from an aspiration to a reality.

  PublisherOA PDFDOI

• Revisiting the Giant Impact Model for Mercury

  Lunar and Planetary Science Conference · 2020-03-01

  article1st authorCorresponding
  Publisher

Recent grants

• Supernova Injection into Forming Planetary Systems

  NSF · $497k · 2009–2013

Frequent coauthors

• H. C. Connolly

  University of Arizona

  17 shared

• J. Poirier

  9 shared

• T.F. Lin

  9 shared

• J. Carpenter

  9 shared

• Andreas Roesch

  9 shared

• Giada Arney

  Goddard Space Flight Center

  7 shared

• Aki Roberge

  Goddard Space Flight Center

  7 shared

• Ariel D. Anbar

  University of Louisiana at Lafayette

  6 shared

Education

• B.S.

  Rensselaer Polytechnic Institute

  1990

• M.S.

  Rensselaer Polytechnic Institute

  1991

• M.S., Astronomy and Astrophysics

  University of Chicago

  1992

• Ph.D., Physics

  University of Illinois, Urbana-Champaign

  1998

Awards & honors

• Asteroid 9926 Desch is named after him