Observations of extrasolar planets are providing new opportunities for furthering our understanding of planetary formation processes. In this paper, we review planet formation and migration scenarios and describe some recent simulations that combine planetary accretion and gas-disc-driven migration. While the simulations are successful at forming populations of low- and intermediate-mass planets with short orbital periods, similar to those that are being observed by ground- and space-based surveys, our models fail to form any gas giant planets that survive migration into the central star. The simulation results are contrasted with observations, and areas of future model development are discussed.
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http://dx.doi.org/10.1098/rsta.2013.0074 | DOI Listing |
Natl Sci Rev
January 2025
Plateau Atmosphere and Environment Key Laboratory of Sichuan Province, School of Atmospheric Sciences, Chengdu University of Information Technology, Chengdu 610225, China.
The weakening and poleward expansion of the Hadley circulation (HC) are considered robust responses of atmospheric meridional circulation to anthropogenic warming. Climate impacts arising from these changes enhance drought conditions and reduce food production in the affected regions. Therefore, understanding the mechanisms of HC changes is critical to anticipating the resultant climate risks.
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January 2025
Department of Earth, Planetary, and Space Sciences, University of California, Los Angeles, CA 90095.
Crystallization of the lunar magma ocean yielded a chemically unique liquid residuum named KREEP. This component is expressed as a large patch on the near side of the Moon and a possible smaller patch in the northwest portion of the Moon's South Pole-Aitken basin on the far side. Thermal models estimate that the crystallization of the lunar magma ocean (LMO) could have spanned from 10 and 200 My, while studies of radioactive decay systems have yielded inconsistent ages for the completion of LMO crystallization covering over 160 My.
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January 2025
Division of Space, Ecological, Arctic, and Resource-limited (SPEAR) Medicine, Department of Emergency Medicine, Massachusetts General Hospital, Boston, MA 02114.
One of the most surprising and important findings of the first human landings on the Moon was the discovery of a very fine layer of lunar dust covering the entire surface of Moon along with the negative impacts of this dust on the well-being and operational effectiveness of the astronauts, their equipment, and instrumentation. The United States is now planning for human missions to Mars, a planet where dust can also be expected to be ubiquitous for many or most landing sites. For these missions, the design and operations of key hardware systems must take this dust into account, especially when related to crew health and safety.
View Article and Find Full Text PDFProc Natl Acad Sci U S A
January 2025
Division of Earth and Planetary Sciences, California Institute of Technology, Pasadena, CA 91125.
Mars Sample Return (MSR) has been the highest flagship mission priority in the last two Planetary Decadal Surveys of the National Academies of Science, Engineering, and Medicine (hereafter, "the National Academies") and was the highest priority flagship for Mars in the Decadal Survey that preceded them. This inspirational and challenging campaign, like the Apollo program's returned lunar samples, will potentially revolutionize our understanding of Mars and help inform how other planets are explored. MSR's technological advances will keep the NASA and European Space Agency at the forefront of planetary exploration, and data on returned samples will fill knowledge gaps for future human exploration.
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January 2025
Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109.
The NASA Mars 2020 Perseverance Rover Mission has collected samples of rock, regolith, and atmosphere within the Noachian-aged Jezero Crater, once the site of a delta-lake system with a high potential for habitability and biosignature preservation. Between sols 109 and 1,088 of the mission, 27 sample tubes have been sealed, including witness tubes. Each sealed sample tube has been collected along with detailed documentation provided by the Perseverance instrument payload, preserving geological and environmental context.
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