scholarly journals Present and Future Observations of the Earthshine from Antarctica

2012 ◽  
Vol 8 (S288) ◽  
pp. 214-217 ◽  
Author(s):  
Danielle Briot ◽  
Luc Arnold ◽  
Stéphane Jacquemoud
Keyword(s):  
Global Scale ◽  
Spectral Signature ◽  
Research Station ◽  
The Moon ◽  
Spectral Signatures ◽  
The Earth ◽  
Earth Like Planets ◽  
Elementary Mapping ◽  
Absorption Features

AbstractIt is likely that images of Earth-like planets will be obtained in the next years. The first images will actually come down to single dots, in which biomarkers can be searched. Taking the Earth as a example of planet providing life, Earthshine observations showed that the spectral signature of photosynthetic pigments and atmospheric biogenic molecules was detectable, suggesting that, in principle, life on other planets could be detected on a global scale, if it is widely spread and distinguishable from known abiotic spectral signatures. As for the Earth, we already showed that the Vegetation Red Edge which is related to chlorophyll absorption features was larger when continents, versus oceans, were facing the Moon. It proved that an elementary mapping of a planet was even possible. In the frame of the LUCAS (LUmière Cendrée en Antarctique par Spectroscopie) project, the Earthshine has been measured in the Concordia Research Station (Dome C, Antarctica) long enough to observe variations corresponding to different parts of the Earth facing the Moon. An extension of this project, called LUCAS II, would allow long-term observations to detect seasonal variations in the vegetation signal. These data, together with precise measurements of the Earth's albedo, will help to validate a model of global and spectral albedo of our planet.

scholarly journals Present and Future Detection of Terrestrial Biomarkers on Earthshine

2012 ◽  
Vol 8 (S293) ◽  
pp. 65-67
Author(s):  
Danielle Briot ◽  
Luc Arnold ◽  
Stéphane Jacquemoud ◽  
Jean Schneider
Keyword(s):  
Research Station ◽  
The Moon ◽  
Absorption Properties ◽  
Spectral Signatures ◽  
New Methods ◽  
The Earth ◽  
Life Detection ◽  
Set Up ◽  
Chlorophyll Absorption

AbstractIn the context of life detection on terrestrial exoplanets, new methods of search for spectral signatures of chlorophyll and other biomarkers in the Earthshine have been developed in the last few decades. Astronomical observations made at OHP and ESO (NTT) showed a significant signal when continents are facing the Moon. This signal, called the Vegetation Red Edge (VRE), is undoubtedly due to chlorophyll absorption properties. In order to strengthen these results, the LUCAS (LUmière Cendrée en Antarctique par Spectroscopie) project dedicated to the measurement of the Earthshine from the Concordia Research Station (C Dome, Antarctica) has been set up. One of the objectives of LUCAS was to observe prolonged variations of the VRE corresponding to various parts of the Earth facing the Moon. An extension of this project, called LUCAS II, would allow long-term observations to detect seasonal variations of the vegetation signal. These data, together with accurate measurements of the Earth's albedo, will help validate a model of global and spectral albedo of our planet.

scholarly journals Evaporative fractionation of volatile stable isotopes and their bearing on the origin of the Moon

2014 ◽  
Vol 372 (2024) ◽  
pp. 20130259 ◽  
Author(s):  
James M. D. Day ◽  
Frederic Moynier
Keyword(s):  
Global Scale ◽  
Parent Body ◽  
The Moon ◽  
Magma Ocean ◽  
Volatile Elements ◽  
Giant Impact ◽  
The Earth ◽  
Present Distribution ◽  
Volatile Loss

The Moon is depleted in volatile elements relative to the Earth and Mars. Low abundances of volatile elements, fractionated stable isotope ratios of S, Cl, K and Zn, high μ ( 238 U/ 204 Pb) and long-term Rb/Sr depletion are distinguishing features of the Moon, relative to the Earth. These geochemical characteristics indicate both inheritance of volatile-depleted materials that formed the Moon and planets and subsequent evaporative loss of volatile elements that occurred during lunar formation and differentiation. Models of volatile loss through localized eruptive degassing are not consistent with the available S, Cl, Zn and K isotopes and abundance data for the Moon. The most probable cause of volatile depletion is global-scale evaporation resulting from a giant impact or a magma ocean phase where inefficient volatile loss during magmatic convection led to the present distribution of volatile elements within mantle and crustal reservoirs. Problems exist for models of planetary volatile depletion following giant impact. Most critically, in this model, the volatile loss requires preferential delivery and retention of late-accreted volatiles to the Earth compared with the Moon. Different proportions of late-accreted mass are computed to explain present-day distributions of volatile and moderately volatile elements (e.g. Pb, Zn; 5 to >10%) relative to highly siderophile elements (approx. 0.5%) for the Earth. Models of early magma ocean phases may be more effective in explaining the volatile loss. Basaltic materials (e.g. eucrites and angrites) from highly differentiated airless asteroids are volatile-depleted, like the Moon, whereas the Earth and Mars have proportionally greater volatile contents. Parent-body size and the existence of early atmospheres are therefore likely to represent fundamental controls on planetary volatile retention or loss.

Low selenocentric orbits stability analysis

2020 ◽  
Author(s):  
Chongrui Du ◽  
O.L. Starinova
Keyword(s):  
Rate Of Change ◽  
The Sun ◽  
Space Systems ◽  
The Moon ◽  
Orbital Structure ◽  
Motion Modeling ◽  
The Earth ◽  
Long Time ◽  
The Stability

The tasks of studying the Moon require long-term functioning space systems. Most of the low selenocentric orbits are known to be unstable, which requires a propellant to maintain the orbital structure. For these orbits, the main disturbing factors are the off-center gravitational field of the Moon and the gravity of the Earth and the Sun. This paper analyzes the stability of low selenocentric orbits according to passive motion modeling and takes into account these main disturbing factors. We put forward a criterion for determining the stability of the orbit and used it to analyze the circular orbit of the Moon at an altitude of 100 kilometers. According to different initial data and different dates, we obtained ranges of the Moon’s orbits with good stability. At the same time, we analyzed the rate of change in the longitude of the ascending node, and found a stable low lunar orbit which can operate for a long time.

scholarly journals Combustion Synthesis Technology for a Sustainable Settlement Overnight

2018 ◽  
Vol 20 (1) ◽  
pp. 3
Author(s):  
Osamu Odawara
Keyword(s):  
Combustion Synthesis ◽  
Resource Utilization ◽  
High Vacuum ◽  
Thermal Control ◽  
Low Earth Orbit ◽  
Earth Orbit ◽  
The Moon ◽  
The Earth

Space technology has been developed for frontier exploration not only in low-earth orbit environment but also beyond the earth orbit to the Moon and Mars, where material resources might be strongly restricted and almost impossible to be resupplied from the earth for distant and long-term missions performance toward “long-stays of humans in space”. For performing such long-term space explorations, none would be enough to develop technologies with resources only from the earth; it should be required to utilize resources on other places with different nature of the earth, i.e., in-situ resource utilization. One of important challenges of lunar in-situ resource utilization is thermal control of spacecraft on lunar surface for long-lunar durations. Such thermal control under “long-term field operation” would be solved by “thermal wadis” studied as a part of sustainable researches on overnight survivals such as lunar-night. The resources such as metal oxides that exist on planets or satellites could be refined, and utilized as a supply of heat energy, where combustion synthesis can stand as a hopeful technology for such requirements. The combustion synthesis technology is mainly characterized with generation of high-temperature, spontaneous propagation of reaction, rapid synthesis and high operability under various influences with centrifugal-force, low-gravity and high vacuum. These concepts, technologies and hardware would be applicable to both the Moon and Mars, and these capabilities might achieve the maximum benefits of in-situ resource utilization with the aid of combustion synthesis applications. The present paper mainly concerns the combustion synthesis technologies for sustainable lunar overnight survivals by focusing on “potential precursor synthesis and formation”, “in-situ resource utilization in extreme environments” and “exergy loss minimization with efficient energy conversion”.

New Economy in space: Cis-lunar economic circle and analogue simulations in China to the 2061 Horizon

2020 ◽  
Author(s):  
guo linli ◽  
blanc michel ◽  
huang tieqiu ◽  
huang jiangze ◽  
yuan jianping ◽  
...  
Keyword(s):  
International Cooperation ◽  
Lunar Surface ◽  
Space Exploration ◽  
Shaanxi Province ◽  
Lunar Exploration ◽  
Test Field ◽  
The Moon ◽  
Liquid Propellant ◽  
The Earth

<p>    The Moon is sometimes also called the "eighth continent" of the Earth. Determining how to utilize cis-lunar orbital infrastructures and lunar resources to carry out new economic activities extended to the space of the Earth-Moon system is one of the long-term goals of lunar exploration activities around the world. Future long-term human deep-space exploration missions to the Moon, on the Moon surface or using the Moon to serve farther destinations will require the utilization of lunar surface or asteroid resources to produce water, oxygen and other consumables needed to maintain human survival and to produce liquid propellant for the supply of spacecraft on the lunar surface. In complement to exploration activities, Moon tourism in cis-lunar orbit and on the lunar surface will become more and more attractive with the increase of  human spaceflight capacity and the development of commercial space activities. However, the development of a sustainable Earth-Moon ecosystem requires that we solve the following five problems:</p><p>(1)How to design alow-cost cis-lunar space transportation capacity? To find an optimal solution, one must compare direct Earth-Moon flight modes with flights based on the utilization of space stations, and identify the most economical spacecraft architectures.</p><p>(2)How to design an efficient set ofcis-lunar orbital infrastructures combining LEO space stations, Earth-Moon L1/L2 point space stations and Moon bases for commercial tourism, taking into account key issues such as energy, communications and others?</p><p>(3)Significant amounts ofliquid oxygen, water, liquid propellant and structural material will be needed for human bases, crew environmental control and life support systems, spacecraft propulsion systems, Moon surface storage and transportation systems. How to  design in-situ resources utilization (ISRU) of the Moon, including its soil, rocks and polar water ice reservoirs, to produce the needed amounts?</p><p>(4) How to simulate on the Earth surface the different components and key technologies that will enable a future long-term human residence on the Moon surface?</p><p>(5). How to accommodate the co-development of public and commercial space and foster international cooperation? How can space policies and international space law help this co-development?</p><p>    China has made rapid progress in robotic lunar exploration activities in the last 20 years, as illustrated by the recent discoveries provided by the Chang'e-4 lander on the far side of the Moon. By 2061, China will have gone into manned lunar exploration and built Moon bases. In preparation for this new phase of its contribution to space exploration, lunar surface simulation instruments have been built in Beijing, Shenzhen and other places in China. A series of achievements have been made in the field of space life sciences . An ambitious project to establish a large Moon base simulation test field, the Lunar Base Yulin (LBY) project, currently in its design phase in Yulin, Shaanxi Province in China, will allow the verification of key relevant technologies.</p><p>    By the 2061 Horizon, we believe that international cooperation and public-private partnership will be key elements to enable this vision of a new, sustainable cis-lunar space economy.</p>

scholarly journals Analysis of Long-Term Moon-Based Observation Characteristics for Arctic and Antarctic

2019 ◽  
Vol 11 (23) ◽  
pp. 2805 ◽  
Author(s):  
Yue Sui ◽  
Huadong Guo ◽  
Guang Liu ◽  
Yuanzhen Ren
Keyword(s):  
Global Climate Change ◽  
Large Scale ◽  
Global Climate ◽  
Earth Observation ◽  
Polar Regions ◽  
The Moon ◽  
The North ◽  
The Earth ◽  
The Antarctic

The Antarctic and Arctic have always been critical areas of earth science research and are sensitive to global climate change. Global climate change exhibits diversity characteristics on both temporal and spatial scales. Since the Moon-based earth observation platform could provide large-scale, multi-angle, and long-term measurements complementary to the satellite-based Earth observation data, it is necessary to study the observation characteristics of this new platform. With deepening understanding of Moon-based observations, we have seen its good observation ability in the middle and low latitudes of the Earth’s surface, but for polar regions, we need to further study the observation characteristics of this platform. Based on the above objectives, we used the Moon-based Earth observation geometric model to quantify the geometric relationship between the Sun, Moon, and Earth. Assuming the sensor is at the center of the nearside of the Moon, the coverage characteristics of the earth feature points are counted. The observation intervals, access frequency, and the angle information of each point during 100 years were obtained, and the variation rule was analyzed. The research showed that the lunar platform could carry out ideal observations for the polar regions. For the North and South poles, a continuous observation duration of 14.5 days could be obtained, and as the latitude decreased, the duration time was reduced to less than one day at the latitude of 65° in each hemisphere. The dominant observation time of the North Pole is concentrated from mid-March to mid-September, and for the South Pole, it is the rest of the year, and as the latitude decreases, it extends outward from both sides. The annual coverage time and frequency will change with the relationship between the Moon and the Earth. This study also proves that the Moon-based observation has multi-angle observation advantages for the Arctic and the Antarctic areas, which can help better understand large-scale geoscientific phenomena. The above findings indicate that the Moon-based observation can be applied as a new type of remote sensing technology to the observation field of the Earth’s polar regions.

scholarly journals A first analysis of the mean motion of CHAMP

2003 ◽  
Vol 1 ◽  
pp. 95-101
Author(s):  
F. Deleflie ◽  
P. Exertier ◽  
P. Berio ◽  
G. Metris ◽  
O. Laurain ◽  
...  
Keyword(s):  
Orbital Motion ◽  
Surface Forces ◽  
The Moon ◽  
Orbital Elements ◽  
Champ Satellite ◽  
Mean Motion ◽  
The Earth ◽  
The Mean ◽  
Low Altitude

Abstract. The present study consists in studying the mean orbital motion of the CHAMP satellite, through a single long arc on a period of time of 200 days in 2001. We actually investigate the sensibility of its mean motion to its accelerometric data, as measures of the surface forces, over that period. In order to accurately determine the mean motion of CHAMP, we use “observed" mean orbital elements computed, by filtering, from 1-day GPS orbits. On the other hand, we use a semi-analytical model to compute the arc. It consists in numerically integrating the effects of the mean potentials (due to the Earth and the Moon and Sun), and the effects of mean surfaces forces acting on the satellite. These later are, in case of CHAMP, provided by an averaging of the Gauss system of equations. Results of the fit of the long arc give a relative sensibility of about 10-3, although our gravitational mean model is not well suited to describe very low altitude orbits. This technique, which is purely dynamical, enables us to control the decreasing of the trajectory altitude, as a possibility to validate accelerometric data on a long term basis.Key words. Mean orbital motion, accelerometric data

scholarly journals Coupled dynamics and evolution of primordial and recycled heterogeneity in Earth's lower mantle

Solid Earth ◽  
2021 ◽  
Vol 12 (9) ◽  
pp. 2087-2107
Author(s):  
Anna Johanna Pia Gülcher ◽  
Maxim Dionys Ballmer ◽  
Paul James Tackley
Keyword(s):  
Lower Mantle ◽  
Large Scale ◽  
Basal Layer ◽  
Global Scale ◽  
Physical Parameters ◽  
Mantle Heterogeneity ◽  
Mantle Evolution ◽  
Earth Like Planets ◽  
Material Volume

Abstract. The nature of compositional heterogeneity in Earth's lower mantle remains a long-standing puzzle that can inform about the long-term thermochemical evolution and dynamics of our planet. Here, we use global-scale 2D models of thermochemical mantle convection to investigate the coupled evolution and mixing of (intrinsically dense) recycled and (intrinsically strong) primordial heterogeneity in the mantle. We explore the effects of ancient compositional layering of the mantle, as motivated by magma ocean solidification studies, and of the physical parameters of primordial material. Depending on these physical parameters, our models predict various regimes of mantle evolution and heterogeneity preservation over 4.5 Gyr. Over a wide parameter range, primordial and recycled heterogeneity are predicted to co-exist with each other in the lower mantle of Earth-like planets. Primordial material usually survives as medium- to large-scale blobs (or streaks) in the mid-mantle, around 1000–2000 km depth, and this preservation is largely independent of the initial primordial-material volume. In turn, recycled oceanic crust (ROC) persists as large piles at the base of the mantle and as small streaks everywhere else. In models with an additional dense FeO-rich layer initially present at the base of the mantle, the ancient dense material partially survives at the top of ROC piles, causing the piles to be compositionally stratified. Moreover, the addition of such an ancient FeO-rich basal layer significantly aids the preservation of the viscous domains in the mid-mantle. Finally, we find that primordial blobs are commonly directly underlain by thick ROC piles and aid their longevity and stability. Based on our results, we propose an integrated style of mantle heterogeneity for the Earth involving the preservation of primordial domains along with recycled piles. This style has important implications for early Earth evolution and has the potential to reconcile geophysical and geochemical discrepancies on present-day lower-mantle heterogeneity.

scholarly journals Coupled dynamics and evolution of primordial and recycled heterogeneity in Earth's lower mantle

2020 ◽  
Author(s):  
Anna Johanna Pia Gülcher ◽  
Maxim Dyonis Ballmer ◽  
Paul James Tackley
Keyword(s):  
Lower Mantle ◽  
Large Scale ◽  
Basal Layer ◽  
Global Scale ◽  
Physical Parameters ◽  
Mantle Evolution ◽  
Earth Like Planets ◽  
Rich Material ◽  
Geochemical Constraints

Abstract. The nature of compositional heterogeneity in Earth’s lower mantle remains a long-standing puzzle that can inform about the long-term thermochemical evolution and dynamics of our planet. Here, we use global-scale 2D models of thermochemical mantle convection to investigate the coupled evolution and mixing of (intrinsically-dense) recycled and (intrinsically-strong) primordial heterogeneity in the mantle. We explore the effects of ancient compositional layering of the mantle, as motivated by magma-ocean solidification studies, and of the physical parameters of primordial material. Depending on these physical parameters, our models predict various regimes of mantle evolution and heterogeneity preservation over 4.5 Gyrs. Over a wide parameter range, primordial and recycled heterogeneity are predicted to coexist with each other in the lower mantle of Earth-like planets. Primordial material usually survives as mid-to-large scale blobs (or streaks) in the mid-mantle, around 1000–2000 km depth. This preservation is largely independent on the initial primordial-material volume. In turn, recycled oceanic crust (ROC) persists as large piles at the base of the mantle and as small streaks everywhere else. In models with a dense FeO-rich layer that is initially present at the base of the mantle, the FeO-rich material partially survives at the top of ROC piles, causing the piles to be compositionally stratified. Moreover, the addition of an ancient FeO-rich basal layer in the lowermost mantle significantly aids the preservation of the viscous domains in the mid-mantle. Primordial blobs are commonly (but not always) directly underlain by thick ROC piles, and aid their longevity and stability. The preservation of primordial domains along with recycled piles is relevant for Earth as it may reconcile geophysical and geochemical constraints on lower mantle heterogeneity.

Highly Siderophile Element Constraints on Accretion and Differentiation of the Earth-Moon System

Science ◽  
2007 ◽  
Vol 315 (5809) ◽  
pp. 217-219 ◽  
Author(s):  
James M. D. Day ◽  
D. Graham Pearson ◽  
Lawrence A. Taylor
Keyword(s):  
Platinum Group Element ◽  
Group Element ◽  
The Moon ◽  
Core Formation ◽  
Data Set ◽  
Highly Siderophile Elements ◽  
Earth’S Mantle ◽  
The Earth ◽  
Siderophile Elements

A new combined rhenium-osmium– and platinum-group element data set for basalts from the Moon establishes that the basalts have uniformly low abundances of highly siderophile elements. The data set indicates a lunar mantle with long-term, chondritic, highly siderophile element ratios, but with absolute abundances that are over 20 times lower than those in Earth's mantle. The results are consistent with silicate-metal equilibrium during a giant impact and core formation in both bodies, followed by post–core-formation late accretion that replenished their mantles with highly siderophile elements. The lunar mantle experienced late accretion that was similar in composition to that of Earth but volumetrically less than (∼0.02% lunar mass) and terminated earlier than for Earth.

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