Addressing Unresolved Questions About the Solar System with New Lunar Samples from the Apollo Missions

Gregory Brennecka | 20-ERD-001

Project Overview

Three long-standing questions in lunar geology have remained unanswered since samples were first returned from the Moon almost fifty years ago. These include: 1) How old is the Moon? 2) How were the lunar crust and mantle produced? and 3) When did the large craters observed on its surface form? The answers to these questions have implications for when the Earth accreted from the solar nebula, how/if planetary bodies evolve from molten oceans of liquid magma, and whether there was an uptick in meteor bombardment in the inner solar system 3.8 billion years ago that was contemporaneous with the emergence of life. The reason that these questions have remained unanswered is that the relatively large, minimally altered, crustal samples needed to address them are extremely rare. There are none on Earth and only 18 of 2,415 samples collected during the Apollo missions to the Moon have been identified as suitable for the required chronologic investigations.

This work was able to identify new crustal samples in lunar breccias returned by the Apollo missions, and then complete detailed mineralogical, geochemical, and chronological measurements on them to address these three problems. This research took advantage of our past experience identifying and analyzing crustal samples within lunar breccias, as well as our recent development of chronologic methods that require substantially smaller amounts of material than more traditional approaches. By completing these measurements, this work helped constrain the geologic evolution of not only the Moon, but also the inner solar system. In addition, we demonstrated Lawrence Livermore National Laboratory (LLNL)'s preeminence as the foremost lunar chronology institute in the world, which will position LLNL as a lead laboratory to analyze sample returns for upcoming NASA Moon missions.

Mission Impact

This research supports NASA missions to the Moon. Moreover, as the nuclear forensics capabilities at LLNL are dependent on the technical foundations of cosmochemical research, this project supports missions in nuclear forensics and will support LLNL's nuclear, chemical, and isotopic science and technology core competency.

Publications, Presentations, and Patents

Borg L. E. and R. W. Carlson. (in revision) 2022. "The Evolving Chronology of the Moon." Annual Reviews in Earth and Planetary Sciences.

Render J. et al. (in revision) 2022. "Disk Transport Rates from Ti isotopic Signatures of Refractory Inclusions." Meteoritics & Planetary Science.

Render J. et al. 2022. "Solar System Evolution and Terrestrial Planet Accretion Determined by Zr isotopic Signatures of Meteorites." Earth & Planetary Science Letters 595, 117748.

Borg, L. E., G.A. Brennecka, and T.S. Kruijer. 2022. "The Origin of Volatile Elements in the Earth-Moon System." Proceedings of the National Academy of Sciences, 119(8).

Bekaert D. et al. 2021. Fossil Records of Early Solar Irradiation and Cosmolocation of the CAI Factory: A Reappraisal." Science Advances 7, eabg8329.

Vernazza P. et al. 2021. "Sample Return of Primitive Matter from the Outer Solar System." Experimental Astronomy,

Render J. and G.A. Brennecka. 2021. "Isotopic Signatures as Tools to Reconstruct the Primordial Architecture of the Solar System." Earth & Planetary Science Letters 555, 116705.

Burkhardt C. et al. 2021. "Terrestrial Planet Formation from Lost Inner Solar System Material." Science Advances 7, eabj7601.

Bryson J.F.J. and G.A. Brennecka. 2021. "Constraints on Chondrule Generation, Disk Dynamics, and Asteroid Accretion from the Compositions of Carbonaceous Meteorites." The Astrophysical Journal 912:163.

Wimpenny J., L. E. Borg, and K. Sio. 2021. "The Gallium Isotopic Composition of the Moon." Earth & Planetary Science Letters, 578, 117318.

Brennecka G. A. et al. 2020. "Astronomical Context of Solar System Formation from Molybdenum Isotopes in Meteorite Inclusions." Science 370, 837-840.

Borg L. E., W. Cassata, J. Wimpenny, A. Gaffney, and C. Shearer. 2020. "The Formation and Evolution of the Moon's Crust Inferred from the Sm-Nd Isotopic Systematics of Highlands Rocks." Geochimica et Cosmochimica Acta. 290, 312-332.

Wimpenny J., N. Marks, L. Borg, J. Badro, and R. Ryerson. 2020. "Constraining the Behavior of Gallium Isotopes During Evaporation at Extreme Temperatures. "Geochimica et Cosmochimica Acta, 290, 312-332.

Schneider J. et al. 2020."Early Evolution of the Solar Accretion Disk inferred from Cr-Ti-O Isotopes in Individual Chondrules." Earth & Planetary Science Letters 551, 116585.

Kruijer T. S., L. E. Borg, J. Wimpenny, and C.K. Sio. 2020. "Onset of Magma Ocean Solidification on Mars Inferred from Mn-Cr Chronometry." Earth & Planetary Science Letters 542, 116315.

Kruijer T. S., T. Kleine, and L.E. Borg. 2020. "The Great Isotopic Dichotomy of the Early Solar System." Nature Astronomy. 4, 32-40.

Sio C. K., L. E. Borg, and W.S. Cassata. 2020. "The Timing of Lunar Solidification and Mantle Overturn Recorded in Ferroan Anorthosite 62237." Earth & Planetary Science Letters 538, 116219.