Humanity has long been fascinated by the planet Mars. Was its climate ever conducive to life? What is the atmosphere like today and why did it change so dramatically over time? Eleven spacecraft have ...successfully flown to Mars since the Viking mission of the 1970s and early 1980s. These orbiters, landers and rovers have generated vast amounts of data that now span a Martian decade (roughly eighteen years). This new volume brings together the many new ideas about the atmosphere and climate system that have emerged, including the complex interplay of the volatile and dust cycles, the atmosphere-surface interactions that connect them over time, and the diversity of the planet's environment and its complex history. Including tutorials and explanations of complicated ideas, students, researchers and non-specialists alike are able to use this resource to gain a thorough and up-to-date understanding of this most Earth-like of planetary neighbours.
Research into the geological processes operating on Mars relies on interpretation of images and other data returned by unmanned orbiters, probes and landers. Such interpretations are based on our ...knowledge of processes occurring on Earth Terrestrial analog studies therefore play an important role in understanding the geological features observed on Mars. This 2007 book presents direct comparisons between locales on Earth and Mars, and contains contributions from leading planetary geologists to demonstrate the parallels and differences between these two neighboring planets. Mars is characterized by a wide range of geological phenomena that also occur on Earth, including tectonic, volcanic, impact cratering, eolian, fluvial, glacial and possibly lacustrine and marine processes. The book provides terrestrial analogs for data sets from Mars Global Surveyor, Mars Odyssey, Mars Exploration Rovers and Mars Express, and will therefore be a key reference for students and researchers of planetary science.
Our knowledge of Mars has changed dramatically in the past 40 years due to the wealth of information provided by Earth-based and orbiting telescopes, and spacecraft investigations. Recent ...observations suggest that water has played a major role in the climatic and geologic history of the planet. This textbook covers our understanding of the planet's formation, geology, atmosphere, interior, surface properties, and potential for life. This interdisciplinary textbook encompasses the fields of geology, chemistry, atmospheric sciences, geophysics, and astronomy. Each chapter introduces the necessary background information to help the non-specialist understand the topics explored. It includes results from missions through 2006, including the latest insights from Mars Express and the Mars Exploration Rovers. Containing the most up-to-date information on Mars, this textbook is essential reading for graduate courses, and an important reference for researchers.
The last surface-level aqueous environments on Mars were likely sulfurous brines that formed as the climate cooled and large bodies of water receded during the transition from the wet Noachian to the ...dry Hesperian (4.1 – 3.0 Gya). To understand the diversity of microorganisms that could have inhabited such environments and their associated biosignatures, we turn to analogous environments on Earth. Here we investigated biofilm communities and their associated biosignatures at Gypsum Hill, (GH), a perennial cold spring system located at nearly 80°N on Axel Heiberg Island in the Canadian high Arctic. The biofilms develop during the summer months alongside the oligotrophic and sulphur rich GH brines and spread out along the flood plains formed by meltwater and spring run-off. Our objective was to link the microbial community structure of the biofilms to geochemical changes across the GH site as an analog to the micro-niches that could have formed during the recession of an ancient Martian Ocean. We collected 14 morphologically distinct biofilms over two field season and found that minor variations in chemistry between proximal sites impacted community structure. 16S amplicon sequencing revealed that biofilms closest to outflow channels were dominated by sulfur oxidizing bacteria, suggesting that primary production may be driven by chemolithoautotrophy. The community structure shifted towards more heterotrophic and phototrophic populations the further the biofilms appeared from a spring source. Microbial eukaryotes at the GH site were investigated for the first time through 18S sequencing with diatoms and photoautotrophic algae dominating all biofilms. Lastly, we linked the biofilm communities to potential biosignatures by examining lipid profiles to help guide the search and identification of potential remnants of hypothetical ancient Martian life.
Splitting CO[sub.2] in Intense Pulsed Plasma Jets Scurtu, Adrian; Ticoş, Dorina; Mitu, Maria Luiza ...
International journal of molecular sciences,
04/2023, Letnik:
24, Številka:
8
Journal Article
Recenzirano
The splitting of COsub.2 was studied in a pulsed plasma discharge produced in a coaxial gun at voltages between ~1 and 2 kV and peak discharge currents of 7 to 14 kA. The plasma was ejected from the ...gun at a speed of a few km/s and had electron temperatures between 11 and 14 eV with peak electron densities ~2.4 × 10sup.21 particles msup.−3. Spectroscopic measurements were carried out in the plasma plume produced at pressures between 1 and 5 Torr, and evidence of COsub.2 dissociation into oxygen and CO was found. An increased discharge current led to the observation of more intense spectra lines and the presence of new oxygen lines, which implies more dissociation channels. Several dissociation mechanisms are discussed, the main candidate being the splitting of the molecule by direct electron impact. Estimates of dissociation rates are made based on measured plasma parameters and interaction cross-sections available in the literature. A possible application of this technique is in future Mars missions where the coaxial plasma gun running in the atmosphere could be able to produce oxygen at a rate of the order of over 100 g per hour in a highly repetitive regime.
Covering the first five decades of the exploration of Mars, this atlas is the most detailed visual reference available. It brings together, for the first time, a wealth of information from diverse ...sources, featuring annotated maps, photographs, tables and detailed descriptions of every Mars mission in chronological order, from the dawn of the space age to Mars Express. Special attention is given to landing site selection, including reference to some missions that were planned but never flew. Phobos and Deimos, the tiny moons of Mars, are covered in a separate section. Contemporary maps reveal our improving knowledge of the planet's surface through the latter half of the twentieth century. Written in non-technical language, this atlas is a unique resource for anyone interested in planetary sciences, the history of space exploration and cartography, while the detailed bibliography and chart data are especially useful for academic researchers and students.
The "Heat Flow Property Package Instrument" (HP.sup.3) is part of NASA's current Mars mission "InSight", which was launched in 2018 and currently operates on the surface of Mars. The instrument needs ...to remain at its initial position and orientation during operation. Although the landing site can have significant tilt and can be covered with low cohesion soil, any mechanical excitation might make the instrument slip. Therefore, the instrument is using a tailored feet design, which can withstand lateral loads. Future instruments might require higher resistance against slip. This can be due to stronger tilted landing sites or due to higher shocks emitted from stronger penetration probes. This paper introduces a novel design for those instruments based on the idea of the "spaced-link track" of Bekker to further minimize slippage. This design concept is originally used on tracks of heavy machinery. It is presented how the major design feature can be incorporated into the current design. A newly developed analytical-numerical model is utilized to estimate the track force of the new design. The paper closes with a design study at which the new design and the current design are compared to each other for different sized feet.
Within the Ca-Al-silicate system, dense, layered hexagonal phases occur at high temperatures and pressures between 20 and 23 GPa. They have been observed both in nature and in experiments. In this ...study, we describe the endmember with a dominant sixfold coordinated Si as a mineral zagamiite (IMA 2015-022a). This new mineral identified in Martian meteorites has a general formula of (Ca,Na)(Al,Fe,Mg)sub.2(Si,Al,□)sub.4Osub.11, thus defining CaAlsub.2Sisub.3.5Osub.11 as a previously unknown endmember of the hexagonal CAS phases. Zagamiite assumes space group P6sub.3/mmc with a unit cell of a = 5.403(2) Å, c = 12.77(3) Å, V = 322.9(11) Åsup.3, and Z = 2. Zagamiite contains significant Fe and Mg and a substantial deficit of Na relative to plagioclase of an equivalent Al/Si, suggesting that it was formed through crystallization from a melt that was derived from a plagioclase-dominant mixture of plagioclase and clinopyroxene above the solidus beyond 20 GPa.
This paper is dedicated to identifying stable equilibrium positions of the tether systems attached to the Lsub.1 or Lsub.2 libration points of the Mars-Phobos system. The orbiting spacecraft ...deploying the tether is at the Lsub.1 or Lsub.2 libration point and is held at one of these unstable points by the low thrust of its engines. In this paper, the analysis is performed assuming that the tether length is constant. The equation of motion for the system in the polar reference frame is obtained. The stable equilibrium positions are found and the dependence of the tether angular oscillation period on the tether length is determined. An analytical solution in the vicinity of the stable equilibrium positions for small angles of deflection of the tether from the local vertical is obtained in Jacobi elliptic functions. The comparison of the numerical and analytical solutions for small angles of deflection is performed. The results show that the dependencies of the oscillation period on the length of the tether are fundamentally different for Lsub.1 and Lsub.2 points. Analytical expressions for the tether tension are derived, and the influence of system parameters on this force is investigated for static and dynamic cases.
![Splitting CO[sub.2] in Inte...](http://api.summon.serialssolutions.com/2.0.0/image/issn/XR4PS5YY4K/1422-0067/small "Splitting CO[sub.2] in Intense Pulsed Plasma Jets")
PDF
![Zagamiite, CaAl[sub.2]Si[su...](http://api.summon.serialssolutions.com/2.0.0/image/issn/XR4PS5YY4K/2075-163X/small "Zagamiite, CaAl[sub.2]Si[sub.3.5]O[sub.11], the Hexagonal High-Pressure CAS Phase with Dominant Si, as a Mineral from Mars")
