Northern Plains Of Mars Research Articles

Genetic types of mud volcanism in the Cydonia and Acidalia regions of Mars

Small cone/mound-shaped structures are widespread on the northern plains of Mars. They are usually interpreted as mud volcanoes because of their close morphological resemblance to mud volcanoes on Earth (for example, in Azerbaijan and near the Sea of Azov). If this interpretation is correct, the small cones/mounds could be evidence of the existence of an extensive subsurface mud source, which, in turn, could be formed by the bottom sediments of a large water reservoir (ocean) that existed on the northern plains of Mars in the past eras of this planet’s geological history. Compared to mud volcanoes on Earth, the morphology of small cones/mounds on Mars varies over a wider range and, which may be due to a greater variety of mechanisms of formation of Martian cones/ mounds. In this study, we studied the morphology of small hills in the Cydonia and eastern Acidalia regions, which are located near the dichotomous boundary within the northern plains of Mars and found that there are 5types of cones/mounds, whose morphology probably characterizes the water-mud reservoir features.

Decameter-scale rimmed depressions in Utopia Planitia: Insight into the glacial and periglacial history of Mars

Currently, Mars appears to be in a frozen state, with the clear majority of the planet's surface maintaining year-round sub-zero temperatures. The discovery of features consistent with landforms found in periglacial environments on Earth, suggests a recent climate history for Mars dominated by the presence of permafrost and/or freeze-thaw cycling. Landforms indicative of such periglacial activity include hummocky, polygonized, scalloped, and pitted terrains in the mid-to high-latitudes of both hemispheres. The detection of near-surface and surface ice by the Phoenix lander, excavation of ice by recent impacts, complemented by interpreted results from the SHAllow RADar (SHARAD) instrument, further unveil a landscape in the mid-latitudes enriched in subsurface ice. We report here on the landscape analysis of a region within Utopia Planitia, where we aim to assess the influence of periglacial processes in the formation of a new landform that we have dubbed ‘Decameter-scale Rimmed Depressions’ or DRDs for short. These features are small-scale depressions surrounded by a narrow rim, ranging from <1 ​m to no higher than a few metres in height. We categorized 3 different DRD morphologies: ellipse morphologies, labyrinth, and tear-drops. DRDs share many morphological similarities with so-called “brain terrain”, although unlike “brain terrain”, most of the DRDs we mapped occur on intra-crater plains and not in association with glacial flow features. The presences of isolated fully enclosed ellipse morphologies is also a notable difference. We discuss the possibility that “brain terrain” and DRDs are genetically different features, but given the similarity in morphology and geographic distribution, we find this unlikely. Thus, while we cannot rule out an origin of DRDs through periglacial sorting, we favour a process for DRD formation similar to that proposed “brain terrain”, whereby ground ice, likely in the form of buried glacial ice, underwent thermal contraction and differential degradation, resulting in the formation of the landform that we see today. DRDs thus represent a further morphological marker for the presence of ground ice in the northern plains of Mars.

Dust Production by Abrasion of Eolian Basalt Sands: Analogue for Martian Dust

AbstractDust is nearly ubiquitous on Mars, covering much of the planet's surface, having been redistributed by dust storms. Analysis of dust via landed instrumentation indicates a basaltic composition for its protolith; the same is interpreted for the dark dune sands encountered at rover field sites. In this paper, we used samples of eolian sands derived from basaltic volcanoes in an experiment to simulate dust production from basalt dune sands within an abrasion chamber. In addition, we used samples from gypsum dunes because gypsum is found within dune fields on the northern plains of Mars. The results, expressed as weight percent of sample reduced to dust, show a remarkably broad range over 4 orders of magnitude. Eolian abrasion of basalt sands can produce similar amounts of dust, as is the case for some desert sands on Earth. Some plausible Mars analogue materials can produce large amounts of dust, suggesting that eolian movement of basaltic sand and volcanic sediments on the surface of Mars is a potential source of fine‐grained sediment or dust.

Evidence for large reservoirs of water/mud in Utopia and Acidalia Planitiae on Mars

Utopia and Acidalia Planitiae show a set of similar morphologic features indicative of the presence of large reservoirs of water/mud in these regional topographic lows. The most important of these features are: (1) impact crater ejecta morphology that progressively changes from ballistic/rampart at the basins periphery to strongly degraded pancake-like in the central portions of the basins, and (2) etched flows (interpreted as mudflows) that are concentrated in those regions of the central portions of both basins where the pancake-like ejecta prevail. The Vastitas Borealis Formation (VBF) in Utopia and Acidalia Planitiae represents the uppermost stratigraphic limit of possible reservoirs in both basins and has practically the same age in these regions; ∼3.57 (±0.02) Ga in Utopia Planitia and ∼3.61 (+0.05/−0.08) Ga in Acidalia Planitia. The southern contact of the VBF closely follows specific contour lines in Utopia Planitia (∼−3.6km±54m, over a distance of ∼1500km) and Acidalia Planitia (∼−3.9km±70m, over the distance of ∼6000km). The presence of the large water/mud reservoirs and the age and topographic configuration of the VBF in Utopia and Acidalia Planitiae are consistent with the existence of an extensive single body of water (an ocean) in the northern plains of Mars.

Aqueous and non-aqueous soil processes on the northern plains of Mars: Insights from the distribution of perchlorate salts at the Phoenix landing site and in Earth analog environments

In 2008, the Phoenix lander returned chemical evidence of perchlorate salts in the soils at its landing site on the northern plains of Mars. Subsequent spectral mapping of the perchlorate using Phoenix׳s multispectral Surface Stereo Imager (SSI) showed that concentrated patches of the salt exist in the subsurface. Because atmospheric formation of Martian perchlorate should form a highly-concentrated layer of salt on the surface, subsurface concentrated patches have been interpreted as evidence that Phoenix soils experienced minor amounts of aqueous reworking after perchlorate formation. Here, we present results from a wide-scale mapping of the Phoenix landing site using SSI multispectral data. We report that, contrary to preliminary case studies, limited occurrences of rocks and soil clods with perchlorate coatings are also found on the undisturbed surface. The discovery of these patches on undisturbed surfaces points to more complex processes operating on modern-day polar soils, perhaps including a combination of aqueous and mechanical processes, such as cryoturbation. Finally, we combine results from this study with an analysis of perchlorate redistribution mechanisms on Earth to illustrate the mechanisms likely responsible for modern processing of soils on the northern plains of Mars.

Boulders of the Vastitas Borealis Formation: Potential origin and implications for an ancient martian ocean

The hypothetical existence of a martian ocean that is based on identification of alleged paleoshorelines has been heavily contested during recent years. Despite the controversy surrounding the paleoshoreline interpretation, additional evidence supporting the idea of a late Hesperian–early Amazonian martian ocean has recently been documented in areas that were potentially covered by this body of water. Most of these observations have been made by the establishment of analogies between martian features within the northern plains and depositional elements from deep-water terrestrial environments (e.g., teardrop-shaped islands, large-scale polygonal terrains, and highalbedo mounds). This paper showcases a new terrestrial, deepwater analogy that also supports the existence of an ancient martian ocean. Boulder-size rocks that are contained within the Vastitas Borealis Formation (VBF) on the northern plains of Mars are compared with boulderand kilometer-scale blocks that have been transported subaqueously as part of mass-transport events in a multitude of terrestrial deep-water environments. These observations suggest that meter-scale rocks that make up part of the VBF might have been emplaced by catastrophic mass-transport events similar to those documented within continental margins on Earth.

Deltaic deposits at Aeolis Dorsa: Sedimentary evidence for a standing body of water on the northern plains of Mars

AbstractA fundamental long‐standing question regarding Mars history is whether the flat and low‐lying northern plains ever hosted an ocean. The best opportunity to solve this problem is provided by stratigraphic observations of sedimentary deposits onlapping the crustal dichotomy. Here, we use high‐resolution imagery and topography to analyze a branching network of inverted channel and channel lobe deposits in the Aeolis Dorsa region, just north of the dichotomy boundary. Observations of stacked, cross‐cutting channel bodies and stratal geometries indicate that these landforms represent exhumed distributary channel deposits. Observations of depositional trunk feeder channel bodies, a lack of evidence for past topographic confinement, channel avulsions at similar elevations, and the presence of a strong break in dip slope between topset and foreset beds suggest that this distributary system was most likely a delta, rather than an alluvial fan or submarine fan. Sediment transport calculations using both measured and derived channel geometries indicate a minimum delta deposition time on the order of 400 years. The location of this delta within a thick and widespread clastic wedge abutting the crustal dichotomy boundary, unconfined by any observable craters, suggests a standing body of water potentially 105 km2in extent or greater and is spatially consistent with hypotheses for a northern ocean.

Magmatic intrusions and deglaciation at mid-latitude in the northern plains of Mars

On Earth, igneous rocks are generally affected by magmatic differentiation and the volume of intrusive bodies is considered to be 5–10 times larger than the volume of volcanic rocks. In contrast, in the case of Mars, the occurrence of olivine-phyric basalts at Gusev crater (McSween, H.Y. [2006]. J. Geophys. Res. (Planets) 111(E10), E02S10), the primitive nature of at least four picritic shergottites (Grott, M. [2013]. Planet. Space Sci. 174, 49–111) and the chemical composition of major volcanic provinces (Baratoux, D., Toplis, M.J., Monnereau, M., Gasnault, O. [2011]. Nature 472, 338–341) suggest that primary melts of the mantle may have commonly reached the surface. These observations, together with sparse morphologic evidence of intrusions in comparison with other terrestrial planets, raise the issue of the conditions for the formation and occurrence of sub-surface zones of magma storage on Mars. In this respect, a series of two types of young (Amazonian) domes located at mid-latitudes in western Arcadia Planitia, East of Phlegra Montes, previously interpreted as surface expressions of intrusive bodies (Farrand, W.H., Lane, M.D., Edwards, B.R., Yingst, R.A. [2011]. Icarus 211, 139–156), are examined here. A fraction of the domes consist of upraised plain material, whereas others, distinguished by a massive core and a large aspect ratio, could be partially exhumed intrusions or extrusions of viscous differentiated magma. The latter interpretation is however not compatible with the mafic compositions inferred from orbital visible and near infrared spectroscopic observations. The thicknesses and radii of both types of domes appear to be related through a power-law relationship with exponents close to 1 or 5/4. These exponent values are not compatible with extrusive morphologies but are characteristic of intrusions magma below an elastic layer (Michaut, C. [2011]. J. Geophys. Res. 10.1029/2010JB008108). We conclude that all types of domes are intrusive bodies. The large aspect ratios of some of these features may be reconciled with a mafic composition and a shallow emplacement (a few hundred meters) as well as a relatively large injection rate. Magma emplacement below an ice-rich horizon that was subsequently removed offers a plausible scenario for their partial exhumation. This scenario is supported by independent signs of ice-removal and deflation events in the northern plains. The formation of these intrusions appear therefore to be related to an unusual context of magma ascent below a thick and low-density ice-rich horizon.

Possible mechanism of boulder clustering on Mars

Whatever causes small-scale polygonal patterned ground (diameter<∼20m) to form pervasively in the northern plains of Mars, appears to also cause boulders to cluster at polygon margins. Assuming that these polygons are caused by the seasonal thermal contraction and expansion of ice in the near-surface to meters of depth, we propose a mechanism that ratchets boulders towards the edges in seasonal cycles on present day Mars. During the contraction (cooling) phase, a CO2 frost layer embeds the boulders. Buffered by condensation and sublimation, the solid CO2 is isothermal and does not contract; we propose that it locks the boulders in place while the H2O ice in the near surface continues cooling and contracts beneath them. In spring/summer seasons when the frost sublimates and heating of the surface begins, the boulders freely move with the expanding near surface ice. We show that over many seasons this process would lead to progressive boulder movement towards polygon edges, with an estimated rate of boulder migration ∼0.1mm/yr under present Mars conditions.

Entry, Descent, and Landing Operations Analysis for the Mars Phoenix Lander

The Mars Phoenix lander was launched August 4, 2007 and remained in cruise for ten months before landing in the northern plains of Mars in May 2008. The one-month Entry, Descent, and Landing (EDL) operations phase prior to entry consisted of daily analyses, meetings, and decisions necessary to determine if trajectory correction maneuvers and environmental parameter updates to the spacecraft were required. An overview of the Phoenix EDL trajectory simulation and analysis that was performed during the EDL approach and operations phase is described in detail. The evolution of the Monte Carlo statistics and footprint ellipse during the final approach phase is also provided. The EDL operations effort accurately delivered the Phoenix lander to the desired landing region on May 25, 2008.

Stability of phases in the Mg(ClO4)2·nH2O system and implications for perchlorate occurrences on Mars

[1] Salt hydrates have been identified on the Martian surface and in some instances can affect or be affected by the H2O flux between the atmosphere and regolith. Recently, perchlorates were identified in the northern plains of Mars by the Phoenix lander, in association with Ca2+, Mg2+, and Na+ cations. Solid perchlorates are rare on Earth, and the stability of perchlorate phases at low temperatures and relative humidities is poorly constrained. We have examined the stability of hydrated phases in the magnesium perchlorate system, Mg(ClO4)2·nH2O, using thermogravimetric and controlled temperature and humidity X-ray diffraction experiments from 253 to 523 K. Our data revealed the existence of three distinct hydrate phases and an anhydrous phase, and the data suggest that the stable form on Mars would be Mg(ClO4)2·6H2O. Rehydration experiments on the anhydrous form at 263 K and 0.5% relative humidity (RH) show complete hydration to the hexahydrate after 12 h. Given the hygroscopic nature of this material and its resistance to dehydration, we conclude that Mg(ClO4)2·6H2O will not undergo dehydration/rehydration-related phase changes on diurnal or seasonal cycles on Mars. Recent evidence suggests a more widespread distribution of perchlorate in the Martian regolith than previously thought, and Mg(ClO4)2·6H2O could thus represent another potential reservoir for H2O.

Compositions of subsurface ices at the Mars Phoenix landing site

NASA's Phoenix Lander uncovered two types of ice at its 2008 landing site on the northern plains of Mars: a brighter, slab‐like ice that broke during Robotic Arm operations; and a darker icy deposit. Spectra from the Phoenix Surface Stereo Imager (SSI) are used to demonstrate that the brighter material consists of nearly pure water ice, which probably formed by migration and freezing of liquid water. The darker icy material consists of ∼30 ± 20 wt% ice, with the remainder composed of fine‐grained soil, indicating that it probably formed as pore ice. These two types of ice represent two different emplacement mechanisms and periods of deposition.

Concentrated perchlorate at the Mars Phoenix landing site: Evidence for thin film liquid water on Mars

NASA's Phoenix mission, which landed on the northern plains of Mars in 2008, returned evidence of the perchlorate anion distributed evenly throughout the soil column at the landing site. Here, we use spectral data from Phoenix's Surface Stereo Imager to map the distribution of perchlorate salts at the Phoenix landing site, and find that perchlorate salt has been locally concentrated into subsurface patches, similar to salt patches that result from aqueous dissolution and redistribution on Earth. We propose that thin films of liquid water are responsible for translocating perchlorate from the surface to the subsurface, and for concentrating it in patches. The thin films are interpreted to result from melting of minor ice covers related to seasonal and long‐term obliquity cycles.

Spectral evidence of volcanic cryptodomes on the northern plains of Mars

The composition and detailed morphology of dome-shaped features located in western Arcadia Planitia and just west of Utopia Planitia were examined in this study utilizing data from Mars Reconnaissance Orbiter and Mars Odyssey sensors. The domes have diameters averaging 1.5 km and heights averaging 160 m, and are generally dark-toned, although some are lighter toned or have split dark and light-toned surfaces. The domes are surrounded by annular deposits comprising, with increasing distance from the domes, dark-toned aprons, light-toned aureoles, and dark-toned aureoles. Compact Reconnaissance Imaging Spectrometer for Mars (CRISM) data over several areas in the western Arcadia region show that spectra from the flanks of several domes have 1 and 2 μm absorption features consistent with the presence of olivine and a high-Ca pyroxene, nominally augite. Modified Gaussian Model (MGM) analysis of these spectra indicates Fe-rich olivine compositions. The tops of domes and the aprons surrounding many domes have negative sloping flat spectra in the near infrared, which is consistent with tachylite-rich, glassy compositions. High Resolution Imaging Science Experiment (HiRISE) images over several domes indicate that relatively high thermal inertia values associated with the tops of domes can be attributed to boulder strewn surfaces. HiRISE images also reveal that light-toned aureoles around domes consist of crenulated ground resembling “brain terrain” textures previously described for ice-rich concentric crater fill elsewhere on the northern plains. The plains surrounding the domes also display lineations that are interpreted to be lava channels or tubes. The combination of volcanic and ice-related features are consistent with the domes having formed as cryptodomes in the near sub-surface. We suggest that the domes could be basaltic in composition if the magmas were degassed and/or highly crystallized, and thus more viscous than typical basaltic magmas. The intrusion of these magmas into an ice-rich horizon would have produced a pervasively jointed chilled margin on the domes, which, once the domes were exposed, would have mechanically weathered to form the dark aprons. The domes could have served as local centers for ice accumulation during periods of high orbital obliquity, which ultimately would have led to the formation of the “brain terrain” surrounding the features. The domes represent late stage volcanic products on the northern plains of Mars and associated features provide more evidence for the role that ice accumulation and modification has played in recent martian history.

Refilling the oceans of early Mars

The northern plains of Mars are thought to have harboured an ocean more than 3.6 billion years ago. Delta deposits and river-valley termini ring the proposed seabed and define an equipotential palaeoshoreline.

Definitive evidence of Hesperian basalt in Acidalia and Chryse planitiae

The surface materials of Acidalia and Chryse planitiae, Mars, have been variably interpreted morphologically as basalt and compositionally as andesite or altered basalt. A thorough survey using the Compact Reconnaissance Imaging Spectrometer for Mars (CRISM) near‐infrared spectrometer reveals olivine and high‐calcium pyroxene signatures in the shallow subsurface exposed by impact craters. These signatures indicate that the near surface of these regions are primarily basaltic in nature and are similar to other regions of Hesperian volcanism across Mars (e.g., Syrtis Major). Previous spectroscopic studies using coarser‐resolution data sets have failed to identify these mafic signatures due to obscuration of the underlying material in addition to the relatively small‐scale exposures in impact craters. The nature of the surficial obscuration material is likely multifaceted and includes the deposition of latitude‐dependent mantling material and the presence of alteration rinds. This observation shows that the northern plains of Mars are basaltic and must be factored into the thermal and surficial evolution of Mars.

Detection of Hydrated Silicates in Crustal Outcrops in the Northern Plains of Mars

The composition of the ancient martian crust is a key ingredient in deciphering the environment and evolution of early Mars. We present an analysis of the composition of large craters in the martian northern plains based on data from spaceborne imaging spectrometers. Nine of the craters have excavated assemblages of phyllosilicates from ancient, Noachian crust buried beneath the plains' cover. The phyllosilicates are indistinguishable from those exposed in widespread locations in the southern highlands, demonstrating that liquid water once altered both hemispheres of Mars.

Expected atmospheric environment for the Phoenix landing season and location

The Phoenix mission, launched on 4 August 2007, landed in the far northern plains of Mars on 25 May 2008. In order to prepare for the landing events and the 90‐sol mission, a significant amount of work has gone into characterizing the atmospheric environment at this location on Mars for northern late spring through midsummer. In this paper we describe the motivation for the work and present our results on atmospheric densities and winds expected during the Phoenix entry, descent, and landing, as well as near‐surface pressure, temperature, winds, surface temperature, and visible optical depth expected over the course of the science mission.

Size‐frequency distributions of rocks on the northern plains of Mars with special reference to Phoenix landing surfaces

The size‐frequency distributions of rocks &gt;1.5 m diameter fully resolvable in High Resolution Imaging Science Experiment (HiRISE) images of the northern plains follow exponential models developed from lander measurements of smaller rocks and are continuous with rock distributions measured at the landing sites. Dark pixels at the resolution limit of Mars Orbiter Camera thought to be boulders are shown to be mostly dark shadows of clustered smaller rocks in HiRISE images. An automated rock detector algorithm that fits ellipses to shadows and cylinders to the rocks, accurately measured (within 1–2 pixels) rock diameter and height (by comparison to spacecraft of known size) of ∼10 million rocks over &gt;1500 km2 of the northern plains. Rock distributions in these counts parallel models for cumulative fractional area covered by 30–90% rocks in dense rock fields around craters, 10–30% rock coverage in less dense rock fields, and 0–10% rock coverage in background terrain away from craters. Above ∼1.5 m diameter, HiRISE resolves the same population of rocks seen in lander images, and thus size‐frequency distributions can be extrapolated along model curves to estimate the number of rocks at smaller diameters. Extrapolating sparse rock distributions in the Phoenix landing ellipse indicate &lt;1% chance of encountering a potentially hazardous rock during landing or that could impede the opening of the solar arrays. Extrapolations further suggest rocks large enough to depress the ground ice table and small enough to be picked up or pushed by the robotic arm should be present within reach for study after landing.

Mission design of the Phoenix Mars Scout mission

The Phoenix Mars Scout Lander, the first robotic explorer in NASA's “Scout Program,” launched on 4 August 2007, will land on the northern plains of Mars in late May 2008, prior to the northern Martian summer. The Phoenix mission “follows the water” by landing in a region where NASA's Mars Odyssey orbiter has discovered evidence of ice‐rich soil very near the Martian surface. For 3 months after arrival, the fixed Lander will perform in situ investigations that will characterize the chemistry of the materials at the local surface, subsurface, and atmosphere, and will identify potential evidence of key elements significant to the biological potential of Mars. The Lander will employ a robotic arm to dig to the ice layer, and will analyze the acquired samples using a suite of deck‐mounted science instruments. The development of the baseline strategy to achieve the objectives of this mission involves the integration of a variety of elements into a coherent mission plan. These elements are involved in defining plans for the launch phase, interplanetary cruise, atmospheric entry, descent and landing, landing site selection, and the surface operations. An overview of the integrated mission plan, from launch through surface operations, is described.