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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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6 records
All sourcesNASA NTRSDOE OSTI
DOE OSTI2021

Olivine Dissolution in Simulated Lung and Gastric Fluid as an Analog to the Behavior of Lunar Particulate Matter Inside the Human Respiratory and Gastrointestinal Systems

With the Artemis III mission scheduled to land humans on the Moon in 2025, work must be done to understand the hazards lunar dust inhalation would pose to humans. In this study, San Carlos olivine was used as an analog of lunar olivine, a common component of lunar dust. Olivine was dissolved in a flow-through apparatus in both simulated lung fluid and 0.1 M HCl (simulated gastric fluid) over a period of approximately 2 weeks at physiological temperature, 37°C. Effluent samples were collected periodically and analyzed for pH, iron, silicon, and magnesium ion concentrations. The dissolution rate data derived from our measurements allow us to estimate that an inhaled 1.0 μm diameter olivine particle would take approximately 24 years to dissolve in the human lungs and approximately 3 weeks to dissolve in gastric fluid. Results revealed that inhaled olivine particles may generate the toxic chemical, hydroxyl radical, for up to 5–6 days in lung fluid. Olivine dissolved in 0.1 M HCl for 2 weeks transformed to an amorphous silica-rich solid plus the ferric iron oxy-hydroxide ferrihydrite. Olivine dissolved in simulated lung fluid shows no detectable change in composition or crystallinity. Equilibrium thermodynamic models indicate that olivine in the human lungs can precipitate secondary minerals with fibrous crystal structures that have the potential to induce detrimental health effects similar to asbestos exposure. Our work indicates that inhaled lunar dust containing olivine can settle in the human lungs for years and could induce long-term potential health effects like that of silicosis.

63 RADIATION, THERMAL, AND OTHER ENVIRON. POLLUTAN↗
DOE OSTI2021

Evaluating the Thickness and Stratigraphy of Ejecta Materials at the Chang’e-4 Landing Site

The landing site of China’s Chang’e-4 (CE-4) probe is located on the mare basalts on the floor of the Von Kármán crater on the lunar far side. The Von Kármán crater is inside the ancient and highly cratered South Pole–Aitken basin, which has experienced complex emplacement sequences of both near and distant ejecta materials. These issues complicated the interpretation of the CE-4 surface in situ measurements of the visible and near-infrared spectrometer and the lunar penetrating radar (LPR) onboard Yutu-2 rover. To evaluate the sources and amounts of all principle foreign materials at the CE-4 landing site, we thoroughly examine the ejecta delivered by crater-forming events that occurred later than the formation of the mare basalts at the CE-4 landing site. We found a total of 16 craters that may have delivered ejecta thicker than 10 cm level superposed on the mare basalts at the CE-4 landing site. Crater Finsen, Von Kármán L, Von Kármán L′, and Maksutov are the top four major foreign material sources, and each of them contributed ejecta thicker than 1 m. Our surveys confirm that the ejecta from Finsen crater are the most dominant foreign materials in the uppermost few meters at the CE-4 landing site and the total impact ejecta deposited upon the mare basalts at the landing site is estimated to be thinner than 30 m. We found that the estimations from Pike’s model are the most consistent with the Yutu-2 LPR observations.

58 GEOSCIENCES↗
DOE OSTI2020

The formation and evolution of the Moon’s crust inferred from the Sm-Nd isotopic systematics of highlands rocks

Ages determined for magnesian and ferroan anorthosite crustal rock suites overlap, suggesting they formed contemporaneously about 4.3–4.5 Ga. A notable exception is the Sm-Nd age previously determined on Mg-suite gabbronorite 67667 which is at least 100 Ma younger than the youngest ferroan anorthosite. New chronologic measurements of 67667 presented here yield concordant Sm-Nd and Rb-Sr mineral isochron ages of 4349 ± 31 Ma and 4368 ± 67 Ma, suggesting the sample is older than previous estimates. Furthermore, a whole rock Sm-Nd isochron of Mg-suite rocks from the Apollo 14, 15, 16, and 17 landing sites yields an age of 4348 ± 25 Ma, indicating that Mg-suite magmatism was widespread and roughly contemporaneous on the lunar nearside. Here, analysis of Sm-Nd internal isochron ages confirms that Mg-suite magmatism was restricted to a period between about 4.33 and 4.35 Ga at the Apollo 14, 15, 16, and 17 landing sites and was synchronous with magmatism at the Apollo 16 site associated with the ferroan anorthosite suite between 4.35 and 4.37 Ga. Magnesian- and ferroan anorthosite suite rocks with ages younger than ~4.33 Ga appear to have experienced slow cooling in the deep lunar interior, so that the ages record when the samples cooled below the closure temperature of the Sm-Nd isotopic system and not the time they crystallized.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2025

Temporal relationships among lunar crustal rocks

Temporal relationships among the three most common suites of lunar crustal rocks have been investigated by obtaining new high precision ages on Felsic/Alkali-suite Quartz monzodiorite Clast B from breccia 15405 and Magnesian-suite norite 78235/6/8/55/56 and comparing them to previously dated ferroan anorthosite sample 60025. The weighted average age of 4337.19 ± 0.49 Ma of 15405 Clast B is defined by zircon U-Pb and Pb-Pb ages as well as mineral isochron Sm-Nd and Nd-Nd ages. It is identical to the weighted average age for Apollo 17 norite 78235/6/8/55/56 of 4334.1 ± 3.5 Ma which is defined by Pb-Pb ages measured on baddeleyites in this investigation and less precise Pb-Pb and Sm-Nd ages reported in the literature. Both ages are ∼ 25 Ma younger than the weighted average of Sm-Nd and Pb-Pb ages reported in the literature on ferroan anorthosite 60025 of 4359.3 ± 2.3 Ma. The fact that ages of all three samples are defined by multiple U-Pb, Pb-Pb, Sm-Nd, and 142 Nd- 143 Nd chronometers provide confidence that they record the igneous crystallization history of the samples and do not represent disturbances or mixing lines with no temporal significance. Here, the extent to which these three ages represent broader scale magmatism is difficult to evaluate. Nevertheless, the age defined for 15405 Clast B, 78235/6/8/55/56, and 60025 are contemporaneous with the peak of ages observed in detrital zircons from the Apollo 12, 14, 15, and 17 landing sites (4340 ± 20 Ma), a Mg-suite Sm-Nd whole rock isochron defined by samples from Apollo 14, 15, 16, and 17 landing sites (4348 ± 25 Ma), and a Ferroan Anorthosite-suite Sm-Nd whole rock isochron defined by samples from the Apollo 15 and 16 landing sites (4354 ± 29 Ma). This implies that Ferroan Anorthosite-suite magmatism is temporally distinct and earlier than magmatism associated with the Mg-suite and the Felsic/Alkali-suite, as predicted by the lunar magma ocean model of lunar differentiation. The short 35 ± 10 Ma interval between primary ferroan anorthosite magmatism and secondary magmatism suggests that the lunar crust formed over a limited period of time. Although heat from decay of long-lived isotopes, large impacts, tidal heating associated with interactions between the Earth and Moon, and density driven overturn of the magma ocean have all been invoked to explain production of ancient secondary crustal magmatism, only tidal heating and cumulate overturn are consistent with the apparent short duration of secondary crustal magmatism and the great depth of crystallization implied for some Mg-suite samples. The initial ε 143 Nd values derived from the 15405 Clast B and 78238 Mg-suite norite isochrons, as well as a Mg-suite whole rock isochron are −0.23 ± 0.11, −0.27 ± 0.74, and −0.25 ± 0.09, respectively. They are identical within uncertainty indicating that Mg-suite and Felsic/Alkali-suite magmas were derived from materials that had the same time averaged Sm/Nd ratios since the formation of the solar system. This, combined with the contemporaneous nature of 15405 Clast B and 78235/6/8/55/56 Mg-suite norite, is consistent with evolution of both samples, and likely both magma suites, from a common source through closed system fractional crystallization or partial melting processes.

Chronology↗
DOE OSTI2023

Chronology of alkali anorthosite 14304 clast “b” records basin forming impact at ~3.95 Ga

Alkali-suite rocks constitute one of three major suites of lunar crustal rocks. As such, constraining their formation timescales and petrogenesis is important for understanding the earliest magmatic history of the Moon. However, the magmatic history of alkali-suite rocks is partly obscured by superimposed effects of major basin-forming impact events on the lunar nearside. Consequently, unambiguous crystallization ages of samples from this suite of rocks have not been determined. Here, the aim of this study is to better understand the petrogenetic history of the alkali-suite and the potential superimposed effects of impact metamorphism by determining Sm-Nd, Rb-Sr, and 40 Ar/ 39 Ar ages for an alkali anorthosite clast from Apollo 14 lithic breccia 14304 termed clast “b”. The new chronologic measurements of clast “b” yield concordant Sm-Nd, Rb-Sr, and 40 Ar/ 39 Ar ages of 3947 ± 13 Ma, 3975 ± 34 Ma, and 3937 ± 37 Ma respectively, resulting in a weighted mean age of 3949 ± 11 Ma. This age is not interpreted to date an igneous event related to production of the lunar highlands crust and instead the chronology and petrography of clast “b” are most readily explained by an impact event at ~3.95 Ga that caused near-complete isotopic re-equilibration of the Sm-Nd, Rb-Sr, and 40 Ar/ 39 Ar chronometers. The weighted mean age of 3949 ± 11 Ma of clast “b” is several hundred Ma younger than 4.3–4.4 Ga ages typically determined for samples of other crustal rock suites but in very good agreement with independent estimates for the formation of Imbrium basin ejecta and other marginally older impact events which are thought to have been sampled at the Apollo 14 landing site. Thus, although petrologic and geochemical examination suggest that clast “b” is a pristine igneous clast, its age likely records an impact event at the Apollo 14 landing site. Whereas the various determined ages of clast “b” do not reflect the timescales of alkali-suite magmatism, the relatively low initial Sr and Nd isotopic compositions of clast “b” indicate that its protolith evolved with very low 147 Sm/ 144 Nd and 87 Rb/ 86 Sr that are distinct from estimates for urKREEP but similar to that of lunar plagioclase. This implies that the igneous protolith of clast “b” derived from a plagioclase-dominated KREEP-rich source that must have formed after the formation of the urKREEP source at ~4.35 Ga but well before the impact event recorded by clast “b” at ~3.95 Ga.

58 GEOSCIENCES↗
DOE OSTI2021

The Role of Early Giant-planet Instability in Terrestrial Planet Formation

The terrestrial planets are believed to have formed by violent collisions of tens of lunar- to Mars-size protoplanets at time t < 200 Myr after the protoplanetary gas disk dispersal (t {sub 0}). The solar system giant planets rapidly formed during the protoplanetary disk stage and, after t {sub 0}, radially migrated by interacting with outer disk planetesimals. An early (t < 100 Myr) dynamical instability is thought to have occurred with Jupiter having gravitational encounters with a planetary-size body, jumping inward by ∼0.2–0.5 au, and landing on its current, mildly eccentric orbit. Here we investigate how the giant-planet instability affected the formation of the terrestrial planets. We study several instability cases that were previously shown to match many solar system constraints. We find that resonances with giant planets help to remove solids available for accretion near ∼1.5 au, thus stalling the growth of Mars. It does not matter, however, whether the giant planets are placed on their current orbits at t {sub 0} or whether they realistically evolve in one of our instability models; the results are practically the same. The tight orbital spacing of Venus and Earth is difficult to reproduce in our simulations, including cases where bodies grow from a narrow annulus at 0.7–1 au, because protoplanets tend to spread radially during accretion. The best results are obtained in the narrow-annulus model when protoplanets emerging from the dispersing gas nebula are assumed to have (at least) the mass of Mars. This suggests efficient accretion of the terrestrial protoplanets during the first ∼10 Myr of the solar system.

79 ASTRONOMY AND ASTROPHYSICS↗