LPI | Science

More About Dr. Stopar’s Research

The Moon, Earth’s nearest neighbor, is a fascinating destination for future study and exploration. Since 2007, Dr. Julie Stopar has played an active role in both the science and operations of the Lunar Reconnaissance Orbiter Camera (LROC), a suite of cameras currently in orbit around the Moon on NASA’s Lunar Reconnaissance Orbiter (LRO) spacecraft. One of the main, ongoing objectives of the LRO mission is to collect the data necessary to plan future exploration of the Moon’s surface. The combined LRO-LROC data set is ideal for investigations in lunar science, geology, and exploration, and facilitates collaborative investigations amongst universities, the Lunar and Planetary Institute, other research institutions, and NASA Centers. As more and more data are available, scientists are able to address new and more complex questions — sometimes with surprising results!

Impact Melt

The Lunar Reconnaissance Orbiter Camera (LROC) images have revealed paths where rivers of once-molten rock flowed on the Moon. Some of these rock-rivers are surprising because they occurred on the rims of small, young impact craters. Rock can be melted during the extreme pressures and temperatures associated with an impact cratering event, but craters less than about 5 km in diameter were once thought to not produce enough melted rock in order to initiate flows. Ponds of melted rock can now also be seen in the floors of craters only a few hundred meters in diameter.

Publication Highlights

• Meyer, H. M., J. D. Stopar, S. S. Bhiravarasu, B. W. Denevi, M. S. Robinson (2019) Morphology and physical properties of Orientale light plains and associated flow features on the Moon, 50th Lunar and Planetary Science Conference, abstract 2581.
• Meyer, H., M. S. Robinson, J. D. Stopar (2017) A new look at Surveyor VII from the Lunar Reconnaissance Orbiter Camera, Lunar and Planetary Science Conference 48, abstract 2631.
• Cohen B. A., Lawrence S. J., Petro N. E., Bart G. D., Clegg-Watkins R. N., Denevi B. W., Ghent R. R., Klima R. L., Morgan G. A., Spudis P. D., and Stopar J. D. (2016) Identifying and Characterizing Impact Melt Outcrops in the Nectaris Basin. 47th Lunar and Planetary Science Conference, abstract 1389.
• Giguere T. A., Hawke B. R., Peterson C. A., Lawrence S. J., Stopar J. D., and the LROC Science Team (2015) Impact Melts At Glushko Crater – LROC Revelations. 46th Lunar and Planetary Science Conference, abstract 1308.
• Stopar J. D., Hawke B. Ray, Robinson M. S., Denevi B. W., Giguere T. A., and Koeber S. D. (2014) Occurrence and mechanisms of impact melt emplacement at small lunar craters. Icarus, 243: 337-357, http://dx.doi.org/10.1016/j.icarus.2014.08.011

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Regolith Evolution

The shapes and depths of impact craters, determined from LROC NAC stereo-derived topography (digital terrain models), indicate that craters less than about 400 meters in diameter are usually relatively shallow (lower depth-to-diameter ratios) compared to their larger (simple) crater counterparts. This was an unexpected discovery in the LRO/LROC data! Various factors can affect the morphologies and relative depths of small craters – including impactor and target properties, impact angle and velocity, and degradation (such as landslides). However, these small and shallow craters are consistent with formation in a regolith target and reflect local regolith thickness and evolution.

Publication Highlights

• Rivera-Valentin, E., C. Fassett, C. Neish, S. S. Bhiravarasu, H. M. Meyer, J. Stopar, B. W. Denevi, A. M. Stickle, G. W. Patterson, G. A. Morgan (2023) Multi-wavelength radar characterization of secondary craters within the pole-crossing Tycho ray on the Moon, AGU Fall Meeting, abstract 1241033.
• Singer, K. H. Skjetne, J. Stopar, M. Huffman, C. Chapman, L. Ostrach, B. Jolliff, W. McKinnon (2023) Lunar secondary crater distributions and ejecta fragment velocity distributions: Implications for regolith redistribution, EGU General Assembly, Vienna, Austria 24-28 Apr 2023, abstract EGU23-3992.
• Stopar, J. D., M. S. Robinson, O. S. Barnouin, A. S. McEwen, E. J. Speyerer, S. Sutton, M. R. Henriksen (2017) Relative depths of simple craters and the nature of the lunar regolith. Icarus 298: 34-48, doi:10.1016/j.icarus.2017.05.022
• Clegg-Watkins R. N., Jolliff B. L., Boyd A., Robinson M. S., Wagner R., Stopar J. D., Plescia J. B., and Speyerer E. J. (2016) Photometric characterization of the Chang’e-3 landing site using LROC NAC images. Icarus, 273: 84-95, http://dx.doi.org/10.1016/j.icarus.2015.12.010.

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Localized Volcanic Deposits

A variety of relatively small-area volcanic deposits have erupted onto the Moon’s surface over time. These deposits include silicic lava flows and domes, irregular mare patches (or IMPs), and pyroclastics.

Small, cinder-cone-like, volcanic vents, each less than 3 km in diameter and a few hundred meters in height, have been recently resolved in the high-resolution LROC images. We can now resolve individual layers including spatter and lava flows. Enhanced concentrations of small volcanic vents superposed on several large topographic rises suggest mantle hot-spots, where volcanism may have occurred intermittently over billions of years.

LROC images also reveal the crisp, fresh morphologies of the IMPs that signify recent eruptions, and that the Moon could have been volcanically active in the last 100 million years. A discovery that is surprising because most scientists thought that the Moon’s interior had cooled long ago (nearly one billion years ago)!

Some steep-sided topographic rises, or domes, are associated with unusual compositions. Using recent LROC images, flow fronts and stratigraphic relationships of these domes have finally been revealed. Several of the steep-sided rises, such as the Lassell Massif, are composed of erupted silicic lava flows, pyroclastics, and other volcanic deposits.

Publication Highlights

• Henderson, M. J. B., B.H.N. Horgan, S.J. Lawrence, J.D. Stopar, L.R. Gaddis (2023) Mineralogy of explosive and effusive volcanic edifices in the Marius Hills volcanic complex, Icarus 404, 115628. https://doi.org/10.1016/j.icarus.2023.115628
• Stopar, J. D., H. Vannier, L. R. Gaddis, K. Ivey, B. Horgan, K. Bennett, T. Giguere (2023) Compositional diversity of pyroclastics in J. Herschel crater and around Lavoisier crater, Lunar and Planetary Science Conference, abstract 1587.
• Giguere, T., J. Gillis-Davis, J. Boyce, B. R. Hawke, M. Lemelin, D. Trang, S. Lawrence, J. Stopar, B. Campbell, L. Gaddis, D. Blewett, J. O. Gustafson, C. Peterson, C. Runyon (2020) Volcanic processes in the Gassendi region of the Moon, JGR-P https://doi.org/10.1029/2019JE006034
• Ashley J. W., Robinson M. S., Stopar J. D.,  Glotch T. D., Hawke B. Ray, van der Bogert C. H., Hiesinger H., Lawrence S. J., Jolliff B. L., Greenhagen B. T., Giguere T. A., and Paige D. A. (2016) The Lassell massif—A silicic lunar volcano. Icarus, 273: 248-261, http://dx.doi.org/10.1016/j.icarus.2015.12.036.
• Braden S. E., Stopar J. D., Robinson M. S., Lawrence S. J., van der Bogert C. H., and Hiesinger H. (2014) Evidence for basaltic volcanism on the Moon within the past 100 million years. Nature Geoscience 7: 787–791 http://dx.doi.org/10.1038/ngeo2252
• Lawrence S. J., Stopar J. D., Hawke B. Ray, Greenhagen B. T., Cahill J. T. S., Bandfield J. L., Jolliff B. L., Denevi B. W., Robinson M. S., Glotch T. D., Bussey D. B. J., Spudis P. D., Giguere T. A., and Garry W. B. (2013) LRO observations of morphology and surface roughness of volcanic cones and lobate lava flows in the Marius Hills. J. Geophys. Res. Planets, 118: 615–634, http://dx.doi.org/10.1002/jgre.20060

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Exploration

There are presently no known samples of small-area volcanic deposits in our sample collection. Such deposits, due to their potential to inform interior processes and volatile inventories, are high-priority exploration targets. Other areas of the Moon are important destinations, too, because of their unusual compositions, unique solar illumination conditions (e.g., shaded polar regions), or their potential to constrain the sequence and timing of key events on the Moon (for example, earliest basin formation, or youngest lava flow). By using geologic knowledge gained by studying data from LRO and other spacecraft, we can better plan successful and useful forays to the lunar surface in the years to come.

Publication Highlights

• Stopar, J. D. and J. T. Syposs (2023) Artemis Zone Landing Sites, Science, and Suitability for a Base Camp, LEAG Annual Meeting, September 2023, abstract 2968.
• Stopar J. D., S. J. Lawrence, L. Graham, J. Hamilton, B. Denevi, K. K. John, H. M. Meyer, J. E. Gruener, J. Nunez, D. S. Draper, B. J. Mass, J. M. Greenberg (2019) Ina, Moon: geologic setting, scientific rationale, and site characterization for a small planetary lander concept. Planetary and Space Sciences 171: 1-16, doi:10.1016/j.pss.2019.04.003
• Stopar J. and Meyer H. (2019) Topographic Map Series of the Moon’s South Pole. Lunar and Planetary Institute Regional Planetary Image Facility, LPI Contributions 2169 to 2182. Lunar South Pole Atlas (maps).
• Speyerer E. J., Lawrence S. J., Stopar J. D., Gläser P., Robinson M. S., and Jolliff B. L. (2016) Optimized traverse planning for future polar prospectors based on lunar topography. Icarus 273: 337-345, http://dx.doi.org/10.1016/j.icarus.2016.03.011
• Stopar J. D., Lucey P. G., Sharma S. K., Misra A. K., and Hubble H. W. (2004) A remote Raman system for planetary exploration: Evaluating remote Raman efficiency. Instruments, Methods, and Missions for Astrobiology VII. Edited by Hoover, Richard B.; Rozanov, Alexei Y. Proceedings of the SPIE, Volume 5163, pp. 99-110

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Other Research Interests

Other Publications

• Stopar, J. D., B. Jolliff, E. Speyerer, E. Asphaug, M. Robinson (2018) Potential Impact-induced Water-solid Reactions on the Moon. Planetary and Space Sciences 162: 157-169, doi:10.1016/j.pss.2017.05.010
• Stopar J. D., Taylor G. J., Velbel M. A., Norman M. D., Vicenzi E. P., and Hallis L. J. (2013) Element abundances, patterns, and mobility in Nakhlite Miller Range 03346 and implications for aqueous alteration. Geochimica et Cosmochimica Acta 112: 208-225, http://dx.doi.org/10.1016/j.gca.2013.02.024
• Stopar J. D., Taylor G. J., Hamilton V. E., and Browning L. (2006) Kinetic model of olivine dissolution and extent of aqueous alteration on Mars. Geochimica et Cosmochimica Acta 70: 6136-6152, http://dx.doi.org/10.1016/j.gca.2006.07.039
• Taylor G. J., Stopar J. D., Boynton W. V., Karunatillake S., Keller J. M., Brückner J., Wänke H., Dreibus G., Kerry K. E., Reedy R. C., Evans L. G., Starr R. D., Martel L. M. V., Squyres S. W., Gasnault O., Maurice S., d'Uston C., Englert P., Dohm J. M., Baker V. R., Hamara D., Janes D., Sprague A. L., Kim K. J., Drake D. M., McLennan S. M., and Hahn B. C. (2006) Variations in K/Th on Mars, Journal of Geophysical Research 111: http://dx.doi.org/10.1029/2006JE002676

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