Tom Zega


Tom's background is in solid-state geochemistry (mineralogy/crystallography), cosmochemistry, and electron microscopy. His research interests are focused on the chemical and physical processes that occurred in ancient stars, the early solar system, and parent asteroids of meteorites. He uses transmission electron microscopy, analytical electron microscopy, focused ion-beam microscopy, and scanning transmission X-ray microscopy to determine crystal structure and chemistry of minerals within meteorites down to the atomic level. Such information is used to understand material properties and spatial relationships with surrounding mineral phases. This work is supported by density-functional theory and thermodynamic modeling as a means to decipher astrophysical and cosmochemical histories.


  • Ph.D., 2003, Arizona State University
  • B.A., 1996, Rutgers University

Journal Articles


Seifert L.B., Haenecour P., Ramprasad T., and Zega T.J. (2023) An in situ study of presolar grains and the fine-grained matrices of the Meteorite Hills 00526 and Queen Alexandra Range 97008 unequilibrated ordinary chondrites. Meteoritics & Planetary Science, 1-20,
Che S. and Zega T.J. (2023) Hydrothermal fluid activity on asteroid Itokawa. Nature Astronomy.
Seifert L.B., Haenecour P., Ramprasad T., Brearley A.J., and Zega T.J. (2023) An in situ investigation of the preservation and alteration of presolar silicates in the Miller Range 07687 chondrite. Meteoritics & Planetary Science
Che S., Domanik K.J., and Zega T.J. (2023) In-situ formation of halite in the Sidi El Habib 001 (H5) ordinary chondrite: Implications for hydrothermal alteration in ordinary chondrite parent bodies. Geochimica et Cosmochimica Acta 348, 85-106.
Zanetta P-M., Drexler M., Barton I., and Zega T.J. (2023) Vanadium electronic configuration determination from L2,3 transition in V-oxide compounds and roscoelite. Microscopy and Microanalysis, 29, 459-469.
Dobrica E., Ishii H.A., Bradley J.P….Zega T.J. and the Hayabusa2 Sands Team (2023) Nonequilibrium spherulitic magnetite in the Ryugu samples. Geochimica et Cosmochimica Acta 346, 65-75.


Noguchi T., Matsumoto T, Miyake A., Zega T.J. and the Hayabusa2 Sands Team (2022) A dehydrated space weathered skin cloaking the hydrated interior of Ryugu. Nature Astronomy. In press.
Ramprasad T., Haenecour P., Domanik K., and Zega T.J. (2022) A coordinated analysis of a compact type-A calcium-aluminum-rich inclusion from the Northwest Africa 5028 chondrite: Implications for nebular and parent-body processes. Meteoritics & Planetary Science.
Bernal J., Zega T.J., and Ziurys L.M. (2022) Shock Processing of Silicon Carbide Grains: Experimental Insights into the Formation of Interstellar Fullerenes and Carbon Nanotubes. The Journal of Physical Chemistry,
Mane P., Wallace S., Wallace P., Bose M., Domanik K., Wadhwa M., Zega T.J. (2022) Earliest evidence of nebular shock waves recorded in calcium-aluminum-rich inclusions. Geochmica et Cosmochimica Acta 332, 369-388.
Zanetta P.M., Manga V., Chang Y.J., Ramprasad T., Weber J., Beckett J.R., and Zega T.J. (2022) Atomic-scale characterization of the oxidation state of Ti in meteoritic hibonite: Implications for early solar system thermodynamics. American Mineralogist, DOI:
Thakur A., Muralidharan K., Zega T.J., and Ziurys L. (2022) A nanometric window on fullerene formation in the interstellar medium: Insights from molecular dynamics studies. The Journal of Chemical Physics 156, 154704,
Seifert L.B., Haenecour P., and Zega T.J. (2022) Coordinated analyses of presolar silicate grains from AGB/RGB stars and supernovae. Meteoritics & Planetary Science,



Manga V.R., Muralidharan K., and Zega T.J. (2021) The interplay between twinning and cation inversion in MgAl2O4-spinel: Implications for a nebular thermochronometer. American Mineralogist.

Zega T.J., Manga V., Ciesla F., Muralidharan K., Watanabe K., and Inada H. (2021) Atomic-scale evidence for open-system thermodynamics in the early solar nebula. The Planetary Science Journal, 2, pp. 21.

Schrader D.L., Davidson J., McCoy T.J., Zega T.J., Russell S.S., Domanik K.J., and King A.J. (2021) The Fe/S ratio of pyrrhotite group sulfides in chondrites: An indicator of oxidation and implications for return samples from asteroids Ryugu and Bennu. Geochimica et Cosmochimica Acta 303, 66-91.

Asaduzzaman A., Muralidharan K., and Zega T.J. (2021) Density functional theory driven analysis of the interplay among structure, composition, and oxidation state of titanium in hibonite, spinel, and perovskite. Earth and Space Chemistry



Zega T.J., Haenecour P., and Floss C. (2020) An in situ investigation of several circumstellar oxide and silicate grains in carbonaceous chondrites. Meteoritics & Planetary Science, 55, 1207-1227.



Bernal J.J., Haenecour P., Howe J.Y., Zega T.J., Amari S., and Ziurys L.M. (2019) Formation of interstellar C60 from silicon carbide circumstellar grains. The Astrophysical Journal Letters883:L43.

Schrader D.L. and Zega T.J. (2019) Petrographic and compositional indicators of formation and alteration conditions from LL chondrite sulfides. Geochimica et Cosmochimica Acta 264, 165-179.

Haenecour P., Howe J.Y., Zega T.J., Amari S., Lodders K., Jose J., Kaji K., Sunaoshi T., and Muto A. (2019) Laboratory evidence for co-condensed oxygen- and carbon-rich meteoritic stardust from nova outbursts. Nature Astronomy

Lauretta D.S., DellaGiustina D.N., Bennett C.A., and the OSIRIS-REx Science Team (2019) The unexpected surface of asteroid (101955) Bennu. Nature

Barnouin O.S., Daly M.G., Palmer E.E., and the OSIRIS-REx Science Team (2019) Shape of (101955) Bennu indicative of a rubble pile wih internal stiffness. Nature Geoscience

DellaGiustina D.N., Emery J.P., Golish D.R., and the OSIRIS-REx Science Team (2019) Properties of rubble-pile asteroid (101955) Bennu from OSIRIS-REx imaging and thermal analysis. Nature Astronomy

Hamilton V.E., Simon A.A., Christensen P.R., and the OSIRIS-REx Science Team (2019) Evidence for widespread hydrated minerals on asteroid (101955) Bennu. Nature Astronomy

Hergenrother C.W., Maleszewsi C.K., Nolan M.C., and the OSIRIS-REx Science Team (2019) The operational environment and rotational acceleration of asteroid (101955) Bennu from OSIRIS-REx observations. Nature Communications

Scheeres D.J., McMahon J.W., French A.S., and and the OSIRIS-REx Science Team (2019) They dynamic geophysical environment of (101955) Bennu based on OSIRIS-REx measurements. Nature Astronomy



Schmidt D.R., Woolf N.J., Zega T.J.,and Ziurys L.M. (2018) Extreme 13C, 15N and 17O isotopic enrichment in the young planetary nebula K4-47. Nature 564, 378-381.

Haenecour P, Floss C, Zega T.J., Croat T.K., Wang A., Jolliff B.L., and Carpenter P. (2018) Presolar silicates in the matrix and fine-grained rims around chondrules in primitive CO3.0 chondrites: Evidence for pre-accretionary aqueous alteration of the rims in the solar nebula. Geochimica et Cosmochimica Acta221, 379-405.



Thompson M.S., Zega T.J., Howe J.Y. (2017) In situ experimental formation and growth of Fe nanoparticles and vesicles in lunar soil. Meteoritics & Planetary Science 52, 413-427.



Berger E.L., Lauretta D.S., Zega T.J., and Keller L.P. (2016) Heterogeneous histories of Ni-bearing pyrrhotite and pentlandite grains in the CI chondrites Orguiel and Alais. Meteoritics & Planetary Science doi: 10.1111/maps.12721.

Thompson M.S., Zega T.J., Becerra P., Keane J.T., and Byrne S. (2016) The oxidation state of nanophase Fe particles in lunar soil: Implications for space weathering. Meteoritics & Planetary Science 51, 1082-1095.



Zega T.J., Haenecour P, Floss C., and Stroud R.M. (2015) Circumstellar magnetite from the LAP 031117 CO3.0 chondrite. The Astrophysical Journal, 808, 55.

Gnanaprakasa T.J., Sridhar D., Beck W., Runge K., Potter B.G. Jr., Zega T.J., Deymier P.A., Raghavan S., and Muralidharan K. (2015) Graphene mediated self-assembly of fullerene nanorods. Chemical Communications 51, 1858-1861.

Schrader D.L., Connolly H.C., Jr., Lauretta D.S., Zega T.J., Davidson J., and Domanik K.J. (2015) The formation and alteration of the Renazzo-like carbonaceous chondrites III: Towards understanding the formation of ferromagnesian chondrules. Meteoritics & Planetary Science 50, 15-50.



Thompson M.S., Christofferson R.C., Zega T.J., Keller. L.P. (2014) Microchemical and structural evidence for space weathering in soils from asteroid Itokawa. Earth, Planets and Space, 66:89.

Bose M., Zega T.J., and Williams P. (2014) Assessment of alteration processes on circumstellar and interstellar grains QUE 97416. Earth and Planetary Science Letters, 399, 128-138.

Asaduzzaman A.M., Zega T.J., Laref S., Runge K., Deymier P.A., and Muralidharan K. (2014) A computational investigation of the adsorption of organics on mineral surfaces: Implications for the attachment of volatiles to minerals in the early solar system. Earth and Planetary Science Letters 408, 355-361.

 Zega T.J., Nittler, L.R., Gyngard F., Alexander C.M.O’D., Stroud R.M., and Zinner E.K. (2014) A transmission electron microscopy study of presolar spinel. Geochimica et Cosmochimica Acta 124, 152-169.

Blinova A.I., Zega T.J., Herd C.D.K., and Stroud R.M. (2014) Testing variations within the Tagish Lake Meteorite – I: Mineralogy and petrology of pristine samples. Meteoritics & Planetary Science49, 473-502.



De Gregorio B., Stroud R.M., Nittler L.R., Alexander C.M.O’D., Bassim N.D., Cody G.D., Kilcoyne, A.L.D., Sandford S.A., Milam S.N., Nuevo M., Zega T.J. (2013) Isotopic and chemical variation of organic nanoglobules in primitive meteorites. Meteoritics & Planetary Science 78, 904-928.



Ma C., Connolly H.C. Jr., Beckett J.R., Tschauner O., Rossman G.E., Kampf A.R., Zega T.J., Sweeney Smith S.A., and Schrader D.L. (2011) Brearleyite, Ca12Al14O32Cl2, a new alteration mineral from the NWA 1934 meteorite. American Mineralogist 96, 1199-1206.

Berger, E.L, Zega, T.J., Keller, L.P., and Lauretta, D.S. (2011) Evidence for aqueous activity on Comet 81P/Wild 2 from sulfide mineral assemblages in Stardust samples and CI chondrites. Geochimica et Cosmochimica Acta75, 3501-3513.

Zega, T.J., Alexander, C.M.O’D., Nittler, L.R., and Stroud, R.M. (2011) A transmission electron microscopy analysis of presolar hibonite. The Astrophysical Journal 730, 1-10.

Foos, E.E., Zega, T.J., Tischler, J.G., Stroud, R.M., and Boercker, J.E. (2011) Synthesis of PbSe nanowires: The impact of alkylphosphonic acid addition. Journal of Materials Chemistry21 2616-2623.

Boercker J.E., Clifton E.M., Tischler J.G., Foos E.E., Zega T.J., Twigg M.E., and Stroud R.M. (2011) Size and temperature dependence of band-edge excitons in PbSe nanowires. The Journal of Physical Chemistry Letters 2, 527-531.



Tischler, J.G., Kennedy, T.A., Glaser, E.R., Efros, Al. L., Foos, E.E., Boercker, J.E., Zega, T.J., Stroud, R.M., Erwin, S.C. (2010) Band-edge excitons in PbSe nanocrystals and nanorods. Physical Review B82 245303-245309.

Zega, T.J., Alexander, C.M.O’D., Busemann, H., Nittler, L.R., Hoppe, P., Stroud, R.M., and Young, A.F. (2010) Mineral associations and character of isotopically anomalous organic material in the Tagish Lake carbonaceous chondrite. Geochimica et Cosmochimica Acta74 5966-5983.

De Gregorio B.T., Stroud R.M., Nittler L.R., Alexander C.M.O’D., Kilcoyne A.L., Zega T.J. (2010) Isotopic anomalies in organic nanoglobules from Comet 81P/Wild 2: Comparison to Murchison nanoglobules and isotopic anomalies induced in terrestrial organics by electron irradiation. Geochimica et Cosmochimca Acta 74, 4454-4470.



Busemann, H., Nguyen, A.N., Cody, G.D., Kilcoyne, A.L.D., Stroud, R.M., Zega, T.J., and Nittler, L.R. (2009) Ultra-primitive interplanetary dust particles from the comet 26P/Grigg-Skjellerup dust stream collection. Earth and Planetary Science Letters288 44-57.



Baturina, O.A., Garsany, Y., Zega, T.J., Stroud, R.M., Schull, T., and Swider-Lyons, K.E. (2008) Oxygen reduction reaction on Platinum/Tantalum Oxide electrocatalysts for PEM fuel cells. Journal of the Electrochemical Society 144, B1314-1321.

Zolensky M., Nakamura-Messenger K., Rietmeijer F., Leroux H., Mikouchi T., Ohsumi K., Simon S., Grossman L., Stephan T., Weisberg M., Velbel M., Zega T., Stroud R., Tomeoka K., Ohnishi I., Tomioka N., Nakamura T., Matrajt G., Joswiak D., Brownlee D., Langenhorst F., Krot A., Kearsley A., Ishii H., Graham G., Dai Z.R., Chi M., Bradley J., Hagiya K., Gounelle M., Keller L., Bridges J. (2008) Comparing Wild 2 particles to chondrites and IDPs. Meteoritics & Planetary Science 43, 261-272.

Leroux H., Rietmeijer F.J.M., Velbel M.A., Brearley A.J., Jacob D., Langenhorst F., Bridges J.C., Zega T.J., Stroud R.M., Cordier P., Harvey R.P., Lee M., Gounelle M., and Zolensky M.E. (2008) A TEM study of thermally modified comet 81P/Wild 2 dust particles by interactions with the aerogel matrix during the Stardust capture process. Meteoritics & Planetary Science 43, 97-120.



Zega, T. J., Nittler, L. R., Busemann, H., and Hoppe, P, and Stroud, R. M. (2007) Coordinated isotopic and mineralogic analyses of planetary materials enabled by in situ lift-out with a focused-ion-beam scanning-electron microscope. Meteoritics and Planetary Science 42, 1373-1386.

Bassim, N.D., Twigg, M.E., Mastro, M.A., Eddy, C.R., Zega, T.J., Henry, R.L., Culbertson, J.C., Holm, R.T., Neudeck, P., Powell, J.A., and Trunek, A.J. (2007) Dislocations in III-nitride films grown on 4H-SiC mesas with and without surface steps. Journal of Crystal Growth 304, 103-107.



Zolensky, M.E., Zega, T. J., Yano, H., and the Stardust Min-Pet science team. (2006) Mineralogy and petrology of comet 81P/Wild 2 nucleus samples. Science 314, 1735-1739.

Brownlee D., Tsou P., Aleon J., and the STARDUST science team (2006) Comet 81P/Wild 2 under a microscope. Science 314, 1711-1716.

Zega, T. J., Hanbicki, A. T., Erwin, S. C., Kioseoglou, G., Zutic, I., Kioseoglou, G., Li, C. H., Jonker, B.T., and Stroud, R.M. (2006) Determination of interface atomic structure and its impact on spin transport using Z-contrast microscopy and density-functional theory. Physical Review Letters 96, 196101-196104.

Zega T.J., Garvie L.A.J., Dódony, I., Friedrich H., Stroud R.M., and Buseck P.R. (2006) Polyhedral serpentine grains in CM chondrites. Meteoritics & Planetary Science 41, 681-688.



Zega T.J., Garvie L.A.J., Dódony, I., Buseck P.R. (2004) Serpentine nanotubes in the Mighei CM chondrites. Earth and Planetary Science Letters 223, 141-146.

Garvie, L. A. J., Zega, T. J., and Buseck, P. R. (2004) Nanometer-scale measurements of Fe3+/SFe by electron energy-loss spectroscopy: A cautionary note. American Mineralogist 89, 1610-1616.



Zega, T. J., Garvie, L. A. J., and Buseck, P. R. (2003) Nanometer-scale measurements of iron oxidation states of cronstedtite from primitive meteorites. American Mineralogist 88, 1169-1172.

Zega T.J. and Buseck P.R. (2003) Fine-grained-rim mineralogy of the Cold Bokkeveld CM chondrite. Geochimica et Cosmochimica Acta 67, 1711-1721.



Lauretta D.S., Buseck P.R., Zega T.J. (2001) Opaque minerals in the matrix of the Bishunpur (LL3.1) chondrite: Constraints on the chondrule formation environment. Geochmica et Cosmochimica Acta 65, 1337-1353.