Exploring other worlds

Ling Xin talks to Su Yan from the National Astronomical Observatories of China, Chinese Academy of Sciences, about China’s rise in lunar science

Open questions in lunar science (invited talk)

<p>The Earth’s Moon is a cornerstone and keystone in the understanding of the origin and evolution of the terrestrial, Earth-like planets.  It is a cornerstone in that most of the other paradigms for the origin, modes of crustal formation (primary, secondary and tertiary), bombardment history, role of impact craters and basins in shaping early planetary surfaces and fracturing and modifying the crust and upper mantle, volcanism and the formation of different types of secondary crust, and petrogenetic models where no samples are available, all have a fundamental foundation in lunar science.  The Moon is a keystone in that knowledge of the Moon holds upright the arch of our understand of the terrestrial planets. It is thus imperative to dedicate significant resources to the continued robotic and human exploration of this most accessible of other terrestrial planetary bodies, and to use this cornerstone and keystone as a way to frame critical questions about the Solar System as a whole, and to explore other planetary bodies to modify and strengthen the lunar paradigm.   </p> <p>What is the legacy, the long-term impact of our efforts? The Apollo Lunar Exploration Program revealed the Earth as a planet, showed the inextricable links of the Earth-Moon system, and made the Solar System our neighborhood. We now ask: What are our origins and where are we heading?: We seek to understand the origin and evolution of the Moon, the Moon’s links to the earliest history of Earth, and its lessons for exploration and understanding of Mars and other terrestrial planets. A basis for our motivation is the innate human qualities of curiosity and exploration, and the societal/species-level need to heed Apollo 16 Commander John Young’s warning that “Single-planet species don’t survive!”. These perspectives impel us to learn the lessons of off-Earth, long-term, long-distance resupply and self-sustaining presence, in order to prepare for the exploration of Mars and other Solar System destinations. </p> <p>Key questions in this lunar exploration endeavor based on a variety of studies and analyses (1-3) include:</p> <p>-How do planetary systems form and evolve over time and when did major events in our Solar System occur?</p> <p>How did planetary interiors differentiate and evolve through time, and how are interior processes expressed through surface-atmosphere interactions?</p> <p>-What processes shape planetary surfaces and how do these surfaces record Solar System history?</p> <p>-How do worlds become habitable and how is habitability sustained over time?</p> <p>-Why are the atmospheres and climates of planetary bodies so diverse, and how did they evolve over time?</p> <p>-Is there life elsewhere in the Solar System?</p> <p>Specific lunar goals and objectives will be outlined in this broad planetary science context.</p> <p> </p> <p>References: 1. Carle Pieters et al. (2018) http://www.planetary.brown.edu/pdfs/5480.pdf, 2. Lunar Exploration Analysis Group, https://www.lpi.usra.edu/leag/. 3) Erica Jawin et al. Planetary Science Priorities for the Moon in the Decade 2023-2033: Lunar Science is Planetary Science.</p>

A View to Anorthosites

It seems anorthosites are by far interested by geologists because they give us great information about Earth history and how it was evolved in planetary geology. Planetary geology is subject the geology of the celestial bodies such as the planets and their moons, asteroids, comets, and meteorites. It is nearly abundant in the moon. So, it seems studying of these rocks give us good information about planetary evolution and the own early time conditions. Anorthosites can be divided into few types on earth such as: Archean-age (between 4,000 to 2,500 million years ago) anorthosites, Proterozoic (2.5 billion years ago) anorthosite (also known as massif or massif-type anorthosite) – the most abundant type of anorthosite on Earth, Anorthosite xenoliths in other rocks (often granites, kimberlites, or basalts). Furthermore, Lunar anorthosites constitute the light-colored areas of the Moon’s surface and have been the subject of much research. According to the Giant-impact hypothesis the moon and earth were both originated from ejecta of a collision between the proto-Earth and a Mars-sized planetesimal, approximately 4.5 billion years ago. The geology of the Moon (lunar science) is different from Earth. The Moon has a lower gravity and it got cooled faster due to its small size. Also, it has no plate tectonics and due to lack of a true atmosphere it has no erosion and weathering alike the earth. However, Eric A.K. Middlemost believed the astrogeology will help petrologist to make better petrogenic models to understand the magma changing process despite some terms geological differences among the Earth and other extraterrestrial bodies like the Moon. So, it seems that these future studies will clarify new facts about planet formation in planetary and earth, too.

How has Lunar science developed? A bibliometric analysis and systematic review

Lunar exploration is a significant process to unravel the evolutionary history of the Earth-Moon system and the pivotal foundation for the exploration of the solar system. A total of 49,161 articles recorded in a comprehensive online literature database between 1959 and 2018 were reviewed to address the development of lunar science in six aspects: publication output volume, keywords, journals, authorship, collaboration, and national output efficiency. The development of lunar science experienced rise and fall corresponding to a log-linearized model that could be clearly divided into three stages: space race (1959-1977), silent stage (1978-1996) and renaissance (1997-2018). Keywords extracted from publications as reliable predictors of multidiscipline showed that the well-developed disciplines of lunar science were astronomy, space engineering, earth and planetary science, while other disciplines played important roles in different stages. Researchers had become cooperative rather than independent in publishing in the past sixty years. Countries with higher average annual GDP contributed more to the development of lunar science. The findings of this work help scholars comprehend the development of lunar science for the past, present and future.