scholarly journals Isotopic evidence for volatile replenishment of the Moon during the Late Accretion

2019 ◽  
Vol 6 (6) ◽  
pp. 1247-1254 ◽  
Author(s):  
Yanhao Lin ◽  
Wim van Westrenen
Keyword(s):  
Dynamic Models ◽  
Temporal Evolution ◽  
Carbonaceous Chondrite ◽  
Isotopic Ratios ◽  
Delivery Time ◽  
The Moon ◽  
Lunar Interior ◽  
Delivery Times ◽  
Lunar Samples ◽  
Water Contents

AbstractThe traditional view of a dry, volatile-poor Moon has been challenged by the identification of water and other volatiles in lunar samples, but the volatile budget delivery time(s), source(s) and temporal evolution remain poorly constrained. Here we show that hydrogen and chlorine isotopic ratios in lunar apatite changed significantly during the Late Accretion (LA, 4.1–3.8 billion years ago). During this period, deuterium/hydrogen ratios in the Moon changed from initial carbonaceous-chondrite-like values to values consistent with an influx of ordinary-chondrite-like material and pre-LA elevated δ37Cl values drop towards lower chondrite-like values. Inferred pre-LA lunar interior water contents are significantly lower than pristine values suggesting degassing, followed by an increase during the LA. These trends are consistent with dynamic models of solar-system evolution, suggesting that the Moon's (and Earth's) initial volatiles were replenished ∼0.5 Ga after their formation, with their final budgets reflecting a mixture of sources and delivery times.

scholarly journals The New Moon: Major Advances in Lunar Science Enabled by Compositional Remote Sensing from Recent Missions

Geosciences ◽  
2018 ◽  
Vol 8 (12) ◽  
pp. 498
Author(s):  
Deepak Dhingra
Keyword(s):  
Rapid Evolution ◽  
The Moon ◽  
New Paradigm ◽  
Lunar Science ◽  
Lunar Interior ◽  
New Findings ◽  
Lunar Samples ◽  
Resource Exploration ◽  
Globally Distributed

Volatile-bearing lunar surface and interior, giant magmatic-intrusion-laden near and far side, globally distributed layer of purest anorthosite (PAN) and discovery of Mg-Spinel anorthosite, a new rock type, represent just a sample of the brand new perspectives gained in lunar science in the last decade. An armada of missions sent by multiple nations and sophisticated analyses of the precious lunar samples have led to rapid evolution in the understanding of the Moon, leading to major new findings, including evidence for water in the lunar interior. Fundamental insights have been obtained about impact cratering, the crystallization of the lunar magma ocean and conditions during the origin of the Moon. The implications of this understanding go beyond the Moon and are therefore of key importance in solar system science. These new views of the Moon have challenged the previous understanding in multiple ways and are setting a new paradigm for lunar exploration in the coming decade both for science and resource exploration. Missions from India, China, Japan, South Korea, Russia and several private ventures promise continued exploration of the Moon in the coming years, which will further enrich the understanding of our closest neighbor. The Moon remains a key scientific destination, an active testbed for in-situ resource utilization (ISRU) activities, an outpost to study the universe and a future spaceport for supporting planetary missions.

scholarly journals Understanding the origin and evolution of water in the Moon through lunar sample studies

2014 ◽  
Vol 372 (2024) ◽  
pp. 20130254 ◽  
Author(s):  
Mahesh Anand ◽  
Romain Tartèse ◽  
Jessica J. Barnes
Keyword(s):  
Lunar Soil ◽  
The Moon ◽  
Origin And Evolution ◽  
Water Abundance ◽  
Water Ice ◽  
Lunar Interior ◽  
Lunar Samples ◽  
Future Challenges ◽  
Unambiguous Detection ◽  
Ocean Ridge

A paradigm shift has recently occurred in our knowledge and understanding of water in the lunar interior. This has transpired principally through continued analysis of returned lunar samples using modern analytical instrumentation. While these recent studies have undoubtedly measured indigenous water in lunar samples they have also highlighted our current limitations and some future challenges that need to be overcome in order to fully understand the origin, distribution and evolution of water in the lunar interior. Another exciting recent development in the field of lunar science has been the unambiguous detection of water or water ice on the surface of the Moon through instruments flown on a number of orbiting spacecraft missions. Considered together, sample-based studies and those from orbit strongly suggest that the Moon is not an anhydrous planetary body, as previously believed. New observations and measurements support the possibility of a wet lunar interior and the presence of distinct reservoirs of water on the lunar surface. Furthermore, an approach combining measurements of water abundance in lunar samples and its hydrogen isotopic composition has proved to be of vital importance to fingerprint and elucidate processes and source(s) involved in giving rise to the lunar water inventory. A number of sources are likely to have contributed to the water inventory of the Moon ranging from primordial water to meteorite-derived water ice through to the water formed during the reaction of solar wind hydrogen with the lunar soil. Perhaps two of the most striking findings from these recent studies are the revelation that at least some portions of the lunar interior are as water-rich as some Mid-Ocean Ridge Basalt source regions on Earth and that the water in the Earth and the Moon probably share a common origin.

scholarly journals Coordinated analysis of space weathering characteristics in lunar samples to understand water distribution on the Moon

2021 ◽  
Vol 27 (S1) ◽  
pp. 2260-2262
Author(s):  
Alexander Kling ◽  
Michelle Thompson ◽  
Jennika Greer ◽  
Philipp Heck
Keyword(s):  
Water Distribution ◽  
Space Weathering ◽  
The Moon ◽  
Lunar Samples

scholarly journals 6. The Nature of Asteroid Surfaces, from Optical Polarimetry

1977 ◽  
Vol 39 ◽  
pp. 243-251 ◽  
Author(s):  
A. Dollfus ◽  
J. E. Geake ◽  
J. C. Mandeville ◽  
B. Zellner
Keyword(s):  
The Body ◽  
Space Weathering ◽  
Carbonaceous Chondrites ◽  
The Moon ◽  
Laboratory Measurements ◽  
Surface Textures ◽  
Lunar Samples ◽  
Dark Material ◽  
Polarization Of Light ◽  
Scanning Electron

Telescopic observations of the polarization of light by asteroids are interpreted on the basis of a systematic polarimetric analysis of terrestrial, meteoritic and lunar samples. Laboratory measurements were made using samples with different surface textures, and scanning electron microscope pictures were used to investigate the influence of microtexture and crystalline structure.It is demonstrated that asteioid surfaces do not accumulate thick regolithic layers of micro-fragments, as do the Moon and Mercury. This is because the majority of debris ejected by impacts are lost, due to the low gravitational escape velocity from these bodies. However, asteroids are not bare rocks, but are coated with a thin layer of adhesive debris. This coating apparently has the composition of the body itself. The fact that there is no indication of significant maturation by space weathering suggests that the dust which coats the surface of asteroids is frequently replaced by further impacts.Asteroids may be classified polarimetrically in several groups: those in group C are made of very dark material and behave like carbonaceous chondrites, or very dark Fe-rich basalts; Those in group S correspond to silicates and stony meteorites. A third group represented by Asteroid 21 Lutetia and 16 Psyche may be metallic.

scholarly journals Remotely distinguishing and mapping endogenic water on the Moon

2017 ◽  
Vol 375 (2094) ◽  
pp. 20150391 ◽  
Author(s):  
Rachel L. Klima ◽  
Noah E. Petro
Keyword(s):  
Solar Wind ◽  
Spatial Distribution ◽  
Solar System ◽  
The Moon ◽  
Testing Hypotheses ◽  
Origin And Evolution ◽  
Lunar Interior ◽  
Geological Features ◽  
Insight Into

Water and/or hydroxyl detected remotely on the lunar surface originates from several sources: (i) comets and other exogenous debris; (ii) solar-wind implantation; (iii) the lunar interior. While each of these sources is interesting in its own right, distinguishing among them is critical for testing hypotheses for the origin and evolution of the Moon and our Solar System. Existing spacecraft observations are not of high enough spectral resolution to uniquely characterize the bonding energies of the hydroxyl molecules that have been detected. Nevertheless, the spatial distribution and associations of H, OH − or H 2 O with specific lunar lithologies provide some insight into the origin of lunar hydrous materials. The global distribution of OH − /H 2 O as detected using infrared spectroscopic measurements from orbit is here examined, with particular focus on regional geological features that exhibit OH − /H 2 O absorption band strengths that differ from their immediate surroundings. This article is part of the themed issue ‘The origin, history and role of water in the evolution of the inner Solar System’.

scholarly journals Solid state convection models of the lunar internal temperature

1977 ◽  
Vol 285 (1327) ◽  
pp. 523-536 ◽  
Keyword(s):  
Solid State ◽  
Creep Behaviour ◽  
The Moon ◽  
Internal Temperature ◽  
Thermal Models ◽  
Lunar Interior

Thermal models of the Moon, which include cooling by subsolidus creep and consideration of the creep behaviour of geologic material, provide estimates of 1500- 1600 K for the temperature, and 10 21-1022 cm2/s for the viscosity of the deep lunar interior.

scholarly journals 3/2-approximation algorithm for a single machine scheduling problem

2021 ◽  
Vol 17 (3) ◽  
pp. 240-253
Author(s):  
Natalia S. Grigoreva ◽  
Keyword(s):  
Approximation Algorithm ◽  
Optimization Problem ◽  
Single Machine Scheduling ◽  
Release Time ◽  
Scheduling Problem ◽  
Delivery Time ◽  
Scheduling Problems ◽  
Delivery Times ◽  
Jobshop Scheduling ◽  
Single Processor

The problem of minimizing the maximum delivery times while scheduling tasks on a single processor is a classical combinatorial optimization problem. Each task ui must be processed without interruption for t(ui) time units on the machine, which can process at most one task at time. Each task uw; has a release time r(ui), when the task is ready for processing, and a delivery time g(ui). Its delivery begins immediately after processing has been completed. The objective is to minimize the time, by which all jobs are delivered. In the Graham notation this problem is denoted by 1|rj,qi|Cmax, it has many applications and it is NP-hard in a strong sense. The problem is useful in solving owshop and jobshop scheduling problems. The goal of this article is to propose a new 3/2-approximation algorithm, which runs in O(n log n) times for scheduling problem 1|rj.qi|Cmax. An example is provided which shows that the bound of 3/2 is accurate. To compare the effectiveness of proposed algorithms, random generated problems of up to 5000 tasks were tested.

Geological Characteristics of the Moon

2020 ◽  
Author(s):  
Long Xiao ◽  
James W. Head
Keyword(s):  
The Moon ◽  
Planetary Evolution ◽  
Geological Characteristics ◽  
Lunar Interior ◽  
Geological Processes ◽  
Sequence Of Events ◽  
Geological Features ◽  
History Of ◽  
Lunar Evolution ◽  
Human Exploration

The geological characteristics of the Moon provide the fundamental data that permit the study of the geological processes that have formed and modified the crust, that record the state and evolution of the lunar interior, and that identify the external processes that have been important in lunar evolution. Careful documentation of the stratigraphic relationships among these features can then be used to reconstruct the sequence of events and the geological history of the Moon. These results can then be placed in the context of the geological evolution of the terrestrial planets, including Earth. The Moon’s global topography and internal structures include landforms and features that comprise the geological characteristics of its surface. The Moon is dominated by the ancient cratered highlands and the relatively younger flat and smooth volcanic maria. Unlike the current geological characteristics of Earth, the major geological features of the Moon (impact craters and basins, lava flows and related features, and tectonic scarps and ridges) all formed predominantly in the first half of the solar system’s history. In contrast to the plate-tectonic dominated Earth, the Moon is composed of a single global lithospheric plate (a one-plate planet) that has preserved the record of planetary geological features from the earliest phases of planetary evolution. Exciting fundamental outstanding questions form the basis for the future international robotic and human exploration of the Moon.

scholarly journals PREFACE

1977 ◽  
Vol 285 (1327) ◽  
Keyword(s):  
Recent Decade ◽  
National Committee ◽  
Practical Reasons ◽  
Scientific Programme ◽  
Space Technology ◽  
The Moon ◽  
Related Space ◽  
Space Experiments ◽  
Lunar Samples ◽  
Academy Of Sciences

This volume presents papers delivered during the Royal Society discussion meeting held on 9-12 June 1975 under the auspices of the British National Committee on Space Research. The meeting was organized to present the findings of European and Commonwealth scientists who had participated in the analyses of lunar samples, both as principal and co-investigators in the Apollo lunar sample analysis programme and as analysts of the Luna samples provided by the U.S.S.R. Academy of Sciences under arrangements with national academies. Scientists from the U.S.A. and the U.S.S.R. were also invited to participate and so the meeting became sufficiently representative and its timing appropriate for the much needed attempt to review the whole of the work on lunar samples and the results of related space experiments. It was the purpose of the meeting, and of the Proceedings, to show how the new knowledge about the Moon, acquired over the recent decade from the intensive study made possible by the space technology developed in the U.S.A. and the U.S.S.R., had solved some and thrown light on other fundamental questions about the Moon. For practical reasons the meeting was overweighted in favour of British and European contributions; but this gave an opportunity for these laboratories to express their appreciation to N.A.S.A. and to the U.S.S.R Academy of Sciences for the opportunity to participate in a unique scientific programme. We hope that the publication will perform a service in bringing before scientists, and indeed the public in general, the remarkable increase in our understanding of the Moon which has resulted from the space programme and will show how international collaboration has been such an important feature of it.

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