☆ 4.5 Article

Searching for high alumina mare basalts using Clementine UVVIS and Lunar Prospector GRS data: Mare Fecunditatis and Mare Imbrium

ICARUS (2008)

Journal

ICARUS

Volume 198, Issue 1, Pages 7-18

Publisher

ACADEMIC PRESS INC ELSEVIER SCIENCE

DOI: 10.1016/j.icarus.2008.06.009

Keywords

Moon, surface

Funding

NASA Cosmochemistry [NAG5-12982]
NASA Planetary Geology and Geophysics [NNG05G138G]

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Abstract

In the context of sample evidence alone, the high-alumina (HA) basalts appear to be an unique, and rare variety of mare basalt. In addition to their distinct chemistry, radiometric dating reveals these basalts to be among the oldest sampled mare basalts. Yet, HA hasalts were sampled by four missions spanning a lateral range of similar to 2400 km, with ages demonstrating chat aluminous volcanism lasted at least 1 billion years. This evidence suggests that HA basalts may be a widespread phenomenon on the Moon. Knowing the distribution of HA mare basalts on the lunar surface has significance for models of the origin and the evolution of the Lunar Magma Ocean. Surface exposures of HA basalts can be detected with compositional remote sensing data from Lunar Prospector Gamma Ray Spectrometer and Clementine. We searched the lunar surface for regions of interest (ROIs) that correspond to the intersection of three compositional constraints taken from values of sampled HA basalts: 12-18 wt% FeO, 1.5-5 wt% TiO2, and 0-4 ppm Th. We their determined the true (unobscured by regolith) composition of basalt units by analyzing the rims and proximal ejecta of small impacts (0.4-4 km in diameter) into the mare surface of these ROIs. This paper focuses on two ROIs that are the best candidates for sources of sampled HA basalts: Mare Fecunditatis. the landing site of Luna 16: and northern Mare Imbrium, hypothesized origin of the Apollo 14 HA basalts. We demonstrate Our techniques ability for delineating discrete basalt units and determining which is the best compositional match to the HA basalts sampled by each mission. We identified two units in Mare Fecunditatis that spectrally resemble HA basalts, although only one unit (Iltm) is consistent with the compositional and relative age of the Luna 16 HA samples. Northern Mare Imbrium also reveals two units that are within the compositional constraints of HA basalts, with one (Iltm) best matching the composition of the basalts sampled by Apollo 14. (C) 2008 Elsevier Inc. All rights reserved.

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Global dose distributions of neutrons and gamma-rays on the Moon

Masayuki Naito, Hiroki Kusano, Satoshi Kodaira

Summary: Dose assessment on the lunar surface is crucial for future long-term crewed missions. In addition to galactic cosmic rays, neutrons and gamma-rays are generated by nuclear interactions and natural radioactive nuclides on the Moon. By utilizing simulations and measurement data, neutron and gamma-ray dose distributions on the Moon were obtained. The distributions varied depending on lunar geological features, with the basalt-rich mare having higher neutron dose rates and gamma-ray dose maps similar to the distribution of natural radioactive elements.

SCIENTIFIC REPORTS (2023)