One of the first maps of Mars, published by an Italian astronomer in 1877, with its pattern of canals, fueled belief in intelligent life forms on the distant red planet—a hope that continued into the ...1960s. Although the Martian canals have long since been dismissed as a famous error in the history of science, K. Maria D. Lane argues that there was nothing accidental about these early interpretations. Indeed, she argues, the construction of Mars as an incomprehensibly complex and engineered world both reflected and challenged dominant geopolitical themes during a time of major cultural, intellectual, political, and economic transition in the Western world. Geographies of Mars telescopes in on a critical period in the development of the geographical imagination, when European imperialism was at its zenith and American expansionism had begun in earnest. Astronomers working in the new observatories of the American Southwest or in the remote heights of the South American Andes were inspired, Lane finds, by their own physical surroundings and used representations of the Earth’s arid landscapes to establish credibility for their observations of Mars. With this simple shift to the geographer’s point of view, Lane deftly explains some of the most perplexing stances on Mars taken by familiar protagonists such as Percival Lowell, Alfred Russel Wallace, and Lester Frank Ward. A highly original exploration of geography’s spatial dimensions at the beginning of the twentieth century, Geographies of Mars offers a new view of the mapping of far-off worlds.
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.
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.
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.
Working on Mars Clancey, William J
2012, 20120907, 2019-06-20
eBook
Geologists in the field climb hills and hang onto craggy outcrops; they put their fingers in sand and scratch, smell, and even taste rocks. Beginning in 2004, however, a team of geologists and other ...planetary scientists did field science in a dark room in Pasadena, exploring Mars from NASA's Jet Propulsion Laboratory (JPL) by means of the remotely operated Mars Exploration Rovers (MER). Clustered around monitors, living on Mars time, painstakingly plotting each movement of the rovers and their tools, sensors, and cameras, these scientists reported that they felt as if they were on Mars themselves, doing field science. The MER created a virtual experience of being on Mars. In this book, William Clancey examines how the MER has changed the nature of planetary field science. NASA cast the rovers, Spirit and Opportunity, as "robotic geologists," and ascribed machine initiative ("Spirit collected additional imagery...") to remotely controlled actions. Clancey argues that the actual explorers were not the rovers but the scientists, who imaginatively projected themselves into the body of the machine to conduct the first overland expedition of another planet. The scientists have since left the darkened room and work from different home bases, but the rover-enabled exploration of Mars continues. Drawing on his extensive observations of scientists in the field and at the JPL, Clancey investigates how the design of the rover mission enables field science on Mars, explaining how the scientists and rover engineers manipulate the vehicle and why the programmable tools and analytic instruments work so well for them. He shows how the scientists felt not as if they were issuing commands to a machine but rather as if they were working on the red planet, riding together in the rover on a voyage of discovery. http://www.youtube.com/watch?v=oZQSWSZnTYs&feature=youtube_gdata
Does Explaining Past Success Require Díez, José; Recio, Gonzalo; Carman, Christian
Journal for general philosophy of science,
12/2022, Volume:
53, Issue:
4
Journal Article
![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")
