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Large-Scale Assessment of Polygon-Edge Boulder Clustering in the Martian Northern Lowlands
Get PDFTwo features evident in many images of the martian northern low-lands are polygonal fractures (especially northwards of 60N) and meter-scale surface boulders. Since their first observation, several attempts have been made to classify and study these polygons as well as how the forces that form these polygons may modify the surface. Surface boulders have been used as a potential indicator of such modification, though current studies find evidence both for and against their association with the underlying polygons. Both these investigations are limited by the same fundamental challenge: map-ping the location of surface boulders manually is not practical at large scales. Here, we use the Martian Boulder Automatic Recognition System (MBARS) to provide image-wide assessments of boulder location and size, enabling large-scale assessment of boulder populations. To compare these boulder locations with the underlying polygons, we modified the 2-D Fourier analysis described by Orloff in 2013 to analyze boulder locations. When compared with Orloffs observations of polygon scales, this provides an avenue for large-scale comparison of boulder-cluster scale and polygon scale
Freeze-Thaw Cycling as a Chemical Weathering Agent on a Cold and Icy Mars
Get PDFLiquid water was abundant on early Mars, but whether the climate was warm and wet or cold and icy with punctuated periods of melting is still poorly understood. Modern climate models for Mars tend to predict a colder, icier early climate than previously imagined. In addition, ice and glaciation have been major geologic agents throughout the later Hesperian and Amazonian eras. One process that can act in such climates is repeated freezing and thawing of water on the surface and in the subsurface, and is significant because it can occur anywhere with an active layer and could have persisted for a time after liquid water was no longer stable on Mars surface. As freeze-thaw is the dominant mechanical weathering process in most glacial/periglacial terrains, it was likely a significant geomorphologic driver at local to regional scales during past climates, and would potentially have been most active when day-average surface temperatures exceeded 0 C for part of the year. Indeed, freeze-thaw involving liquid water in the Amazonian is evidenced by abundant geomorphic features including polygonal ground and solifluction lobes requiring seasonal thawing. In addition to physical modification, freezing can drive solutions towards supersaturation and force dissolved solutes out as precipitates. In Mars-like terrains, dissolved solutes are typically dominated by silica. In polar regions on Earth, freeze-thaw cycles have been shown to promote deposition of silica, and freeze-thaw experiments on synthetic solutions found stable amorphous silica that built up over multiple cycles. Freeze-thaw may therefore be an important but overlooked chemical weathering process on Mars. However, our ability to assess its impact on alteration of martian terrains is majorly limited by the current lack of understanding of the alteration phases produced (and formation rates) under controlled freeze-thaw weathering of Mars-relevant materials. To address this knowledge gap, we report results from (1) freeze-thaw weathering products found at a glacial Mars analog site at the Three Sisters, Oregon, and (2) new controlled freeze-thaw experiments on basaltic material
Investigation of Magmatic Activities on Early Mars Using Igneous Mineral Chemistry in Gale Crater, Mars
Get PDFOne objective of rover missions is exploring the geological context of the surroundings. Over the years, igneous petrology and sedimentology have been disconnected, the first investigating magmatic processes and volcanic activities, and the second seeking environmental conditions in the past and assessing the habitability of the planet. Although different, one is related to the other: igneous rocks are altered and broken down, leading to the formation of sedimentary rocks, which can in turn be used to back out the nature of their magmatic source. The Curiosity rover that landed in the 3.7 Gyr old impact crater Gale is traveling through sedimentary rocks. About fifty float rocks have been observed, and several of them with ambiguous texture and composition have been classified as igneous or sedimentary depending on studies such as Jake_M. The composition of several unambiguous igneous rocks has been analyzed [4- 6] but their heterogeneity at a larger instrumental (measurement size < 2 cm) scale prevents the measurement of a bulk composition as performed on Earth. An original approach avoiding these two last issues is to consider igneous mineral chemistry analyzed within igneous and sedimentary rocks to assess magmatic processes that could have formed them. Most Curiosity data are used to explore ancient environmental conditions, and a significant number of compositional analyses are under-explored for constraining magmatic activities. We will present how we can make use of sedimentary data for investigating igneous processes in the vicinity of Gale crater.
Geological Context: We focus on the first 750
martian days, corresponding to measurements in a coherent
lacustrine sedimentary unit called Bradbury,
because all sedimentary rocks were sourced from the
same watershed and appear to have a consistent source
with minimal alteration [2-3]. Igneous detrital minerals
including feldspar and pyroxene, are observed in sedimentary
rocks. Monte Carlo models showed that minimal
cation loss is observed based on the composition
of all Bradbury rocks, implying negligible weathering
[3]. Although clay minerals are detected in few rocks
[7], chemical compositions of rocks can be explained
by a mixture of primary igneous minerals [3]. Variation
of composition within Bradbury rocks can be explained
by mineral sorting and one distinct source
component. While a common magmatic source is suggested,
Bradbury sediments likely come from several
volcanic eruptions from a single magmatic chamber [9-
10]. The occurrence of alkali minerals like sanidine
and K-rich rocks throughout Bradbury supports the
presence of a potassic component, likely trachytic,
while plagioclase and a mafic composition suggest a
basaltic component [8-9].
Instruments: Mineral chemistry can be estimated
by three instruments onboard Curiosity. The CheMin
instrument enables detection of mineral assemblages
using X-ray diffraction (XRD). Using Rietveld refinement,
each mineral is identified according to their 1D
XRD pattern [11]. Note that distinction between pyroxene
minerals is challenging with the CheMin instrument
due to overlapping peaks on XRD patterns
and low angular resolution of the instrument [12].
Then, using least square regression and optimization
algorithms based on unit-cell parameters, mineral
chemistry has been estimated by [11]. Plagioclase
composition has been estimated using the NaAlSi3O8-
CaAl2Si2O8 system and alkali feldspar is based on the
NaAlSi3O8-KAlSi3O8 system (stars in Fig.1). Two
mudstone samples (John Klein and Cumberland) and
one sandstone sample (Windjana) were analyzed by
CheMin at Yellowknife Bay and Kimberley, respectively.
Figure 1. Ternary diagrams of feldspars (top) and pyroxene
(bottom) quadrilateral. Stars correspond to CheMin composition
and the gray patches to ChemCam composition. The
colored dots are the composition of feldspar and pyroxene
that crystallized during fractional crystallization at FMQ+1 of a melt extracted at distinct melting degree during the adiabatic
ascent of a primitive mantle composition, without any
water (left panels) and with 0.5 wt.% of water (right panels)
at distinct pressure.
The ChemCam instrument enables the analysis of
the chemical compositions of rocks at hundreds of micrometer
scale (350-550 m) using laser induced
breakdown spectroscopy (LIBS), which may provide
the composition of minerals when they are larger than
the beam spot (>550 m) [13]. Within >5000 LIBS
points, we performed a typical stoichiometric filtering
allowing us to distinguish 56 feldspar and 10 pyroxene
mineral compositions (grey patches in Fig. 1).
Finally, the Alpha Particle X-ray Spectrometer
(APXS) analyzes the composition of rocks with a 1.6
cm diameter spot size. Monte Carlo mass balance
modeling allowed [3] to decipher a feldspar range varying
between An30 and An40 (Fig. 1).
Discussion: Although there could be a more complex
history and other ways to form the whole compositional
range of igneous minerals analyzed within the
Bradbury formation, we are presenting here simple
magmatic pathways commonly occurring on Earth
using the thermodynamical softwares pMELTS and
rhyoliteMELTS [14]. The objective is to find reasonable
igneous processes that produce minerals that parallel
the compositions of feldspar and pyroxene analyzed
by the Curiosity rover. As commonly observed for
mid-ocean ridge basalts, the adiabatic ascent of a primitive
mantle composition [15] partially melting at 2
GPa has been modeled, followed by the extraction of a
liquid at distinct degrees of partial melting, which undergoes
fractional crystallization at an oxygen fugacity
+1 log unit above the fayalite-magnetite-quartz (FMQ)
buffer within the crust (0.02-0.4 GPa) with H2O = 0-
0.5 wt. %. These latter conditions correspond to those
recorded within igneous clasts from the Noachian martian
breccia NWA 7034 and paired and within Gale
igneous rocks (colored dots in Fig. 1) [16-17]. To
check the reliability of these 2-step models, we also
tested fractional crystallization at similar conditions
(FMQ+1; P=0.02-0.4 GPa; H2O = 0-0.5 wt. %) of
starting compositions corresponding to that of magmas
with distinct melting degrees obtained from isobaric
experiments at 2 GPa [18]. Mineral compositions obtained
from both models are similar.
As shown on Fig. 1, the whole range of observed
feldspar compositions cannot be reproduced by fractionation
of one magma only. Indeed, while alkali feldspar
and Na-plagioclase likely crystallized from fractional
crystallization of a low-degree melt (here
<15%), plagioclase and pyroxene can only be formed
by fractional crystallization of a higher degree melt
(here >19%). The corresponding liquid descent lines
are broadly in agreement with compositions estimated
by ChemCam corresponding to float igneous rocks
(Fig. 2) [4-6].
Figure 2. Silica versus alkali content. Lines show the liquid
lines of descent from magmas with distinct degrees of melting.
Gray patches represents the composition of Gale igneous
rocks [4-6].
Trachytic to rhyolitic magmas crystallize alkali
feldspar, and andesite to dacite magmas likely form
plagioclase. Therefore, at least two starting magmas at
distinct melting degrees, which could easily come from
a single mantle source, are necessary to explain the
whole compositional range of feldspar and pyroxene
analyzed within Bradbury rocks.
Conclusion: Because rocks from the Bradbury
formation are likely originating from the same magmatic
source with minimal weathering as supported by
several studies using different approaches, igneous
mineral chemistry analyzed by CheMin and ChemCam
allows us to back out reasonable magmatic pathways
that could have crystallized them. Fractional crystallization
of at least two starting magmas originating from
distinct melting degrees of a single mantle source can
explain the whole range of feldspar and pyroxene
composition. Both alkaline and sub-alkaline liquids
can be produced, with compositions corresponding to
those of the igneous rocks analyzed by ChemCam
within the Bradbury formation, highlighting the complexity
of Mars magmatism
Fungal Exposure to Meteorite Thin Sections: Developing an Experimental to Observe Biogeochemical Changes
Get PDFThe Astromaterials Acquisition & Curation Office maintains collections of meteorite samples collected as part of the Antarctic Search for Meteorites (ANSMET) program. The chief goal of the curation department is to maintain these meteorites in pristine condition. The Astromaterials Research and Exploration Science (ARES) Directorate has implemented a microbial monitoring program for the meteorite collections that has resulted in the isolation of >100 fungal isolates [1], however it is currently unknown if these isolates could present danger to the collections through bioweathering or secretion of organic compounds. We grew a strain of Fusarium oxysporium isolated from nitrogen gas filters feeding the Meteorite Lab nitrogen gas in the presence of a H5 meteorite thin section to determine if this fungus has the capability of altering the mineral structure of this common meteorite. This first trial was to determine and understand the effects of Fusarium oxysporum growth on the iron content within H5 chondrites and evaluate what additional components are needed in the development of future trial runs. This experiment determined new considerations for handling samples, the nature of microscopic scans before and after the incubation period, and the quality of the samples utilized for the experiment. The results of this experiment were promising and warrant further investigation with a more refined process and timeline
Chalcophile Element Constraints on the Sulfur Content of the Martian Mantle
Get PDFThe sulfur content of the Martian mantle is critical to understanding volcanic volatiles supplied to the surface of Mars and possibly climate. In the absence of Martian mantle rocks, sulfur content of the mantle has been inferred from S contents of Martian meteorites or from sedimentary sulfate abundances. Estimates of the sulfur content of the Martian mantle vary from 390-2,000 ppm, all of which are higher than that of the terrestrial mantle (~250 ppm;). Residual sulfide in the Martian mantle controls the distribution of chalcophile elements during partial melting. In this study, we report new analyses of Martian meteorites, and use the incompatible behavior of As, Tl and Pb to infer the sulfide mode of the Martian mantle using a different set of assumptions than those of prior studies
Overview and Initial Results of SAND-E: Semi-Autonomous Navigation for Detrital Environments
Get PDFUnmanned aerial systems (UAS) and automated terrain analysis for science and navigation are new technologies for planetary exploration. The Mars Helicopter will fly with the Mars2020 rover, the Dragonfly quadcopter will explore Titan, and Soil Properties and Object Classification (SPOC) software will be used for path planning and navigation on the Mars2020 rover. Using an Argo J5 rover instrumented with stereo cameras and Autonomous Soil Assessment System (ASAS) software, and an off the shelf quadcopter, SAND-E tested the use of automated terrain analysis and UAS data for science operations in a Mars-analog environment in Iceland during July of 2019. Scientifically, we sought to determine changes in the physical and chemical properties of sediments along a glacial-fluvial-aeolian transport pathway. Operationally, we tested rover mission-like scenarios that included UAS images and classified terrain images. Here, we present the initial results for both the operations and science elements of the study. Site Selection: A goal of SAND-E is examine sorting and alteration of sediments in fluvial and aeolian environments in both mineral-dominated and glass-dominated basaltic settings. During the first year of the project we focused on a mineral-dominated environment. Selection of the location was based on prior publications that indicated our selected region had a greater abundance of crystalline sediments than other areas fluvial-aeolian settings in Iceland. Other criteria included the presence of both fluvial and aeolian landforms along a transport pathway such that the sediments in transport could be linked to their source rocks. We chose the Skjaldbreidauhraun glacial outwash plain, which sits at the base of Thrisjkull glacier. The site is 30 km north of Thingvellir National Park and ~2 hours from Reykjavik. The outwash plain is fed by two small catchments that drain from the base of the glacier and cut through hyaloclastite and shield volcano bedrock. The drainage progresses from steep alluvial fans near the glacier into a low-sloping fluvial braidplain that becomes confined by the Skjaldbreidur shield volcano and creates a shallow canyon cut into lava bedrock. The fluvial system was a typical braided alluvial environment composed pebble- and cobble-bedded longitudinal bars and sandy channel beds. The river remained active and fluctuated in response to diurnal runoff cycles near the glacier before disappearing into the sandy substrate downstream. The high concentration of suspended sediment in the river was evident by the cloudy water and the silt and clay-sized sediments that draped the channel beds after abandonment and created playas in the lowest sloping areas of the catchment. The entire fluvial system was affected by the winds generated by frontal systems and katabatic flows descending the glacier. This resulted in the formation of aeolian lag deposits and a wind-deflation plain where the fluvial system was not active. Wind ripples and drifts formed in abandoned fluvial channels from aeolian reworking of the sand-sized fluvial sediments. The silt- and clay-sized sediments found in fluvial channels, bar tops, and playas generated dust plumes during high wind events. Our operation sought to capture the variability in this system by sampling from the range of fluvial and aeolian features 6.3 km (proximal), 11.3 km (medial), and 14.4 km (distal) along the river from its origin at the base of glacier
VEG-04: The Effects of Light Quality on Mizuna Mustard Growth, Nutritional Composition, and Organoleptic Acceptability for a Space Diet
Get PDFGrowing fresh, nutritious, palatable produce for crew consumption during spaceflight may provide health-promoting, bioavailable nutrients and enhance the astronaut dietary experience as we move toward longer-duration missions. Tending plants may also serve as a countermeasure for crew psychological stresses associated with spaceflight. However, requirements to support consistent growth of a variety of high quality, nutritious crops under spaceflight environmental conditions remain unclear. This study explores the potential to grow crops for consumption on the International Space Station (ISS) using the Veggie vegetable-production system. VEG-04A and B were two flight tests conducted in 2019 with the leafy green crop mizuna mustard. Mizuna was grown in two Veggie chambers simultaneously, with the chambers set to different red-to-blue light formulations; one Veggie was programmed as "red-rich" and the second as "blue-rich." Light quality is known to impact plant growth, nutrition, microbiology, and organoleptic characteristics on Earth, and the Veggie flight tests examined how these impacts might differ in microgravity. VEG-04A, a 35-day growth test with a single harvest, was initiated in June and harvested in July 2019. At harvest, the astronauts froze half of the edible plant tissue to return to Earth and weighed the remaining half using the Mass Measurement Device (MMD). Weighed samples were then cleaned with produce-sanitizing wipes, and consenting crew members participated in organoleptic evaluation of the fresh produce. The remaining sanitized produce was available for crew consumption as desired. Frozen flight samples were returned at the end of August for microbial and chemical analyses to assess food safety and nutritional quality. No pathogens were detected on VEG-04A flight or ground control samples. On average, bacterial and fungal counts were significantly lower on ground control samples than flight samples. VEG-04B, a 56-day test with multiple harvests from the same plants, assessed sustained productivity. VEG-04B was initiated in October 2019 with three harvests at four, six, and eight weeks after initiation. Challenges with the watering program occurred early during VEG-04A, and several plants failed to survive in both the flight and ground control operations. Thus, prior to VEG-04B, an extra test was conducted to tailor water timing and volumes. This test determined that mizuna grew best if the wicks inside the plant pillow were allowed to dry after plants germinated, reducing persistent water around the stem. The wicks changed from being a conduit for water out of the plant pillow to being a conduit for air into the root zone. This test allowed a fine tuning of methods for VEG-04B. It is our hope that these tests on ISS will help mitigate the risk of an inadequate food supply for long-duration missions by adding fresh vegetables to the crew diet. This research was co-funded by the Human Research Program and Space Biology (MTL#1075) in the ILSRA 2015 NRA call
The New NASA Approach to Reliability and Maintainability
Get PDFIn 2017, after 20 years, NASA issued a major revision of its reliability and maintainability (R&M) policy, NASA-STD- 8729.1A. Formerly NASA required certain specific R&M activities during each succeeding phase of project development. Now NASA requires a project to start by including the initial development of R&M requirements and the devising of strategies to implement and verify them. Rather than resolving all the requirements first and then designing the system, as has been usual in systems design, the design process now is to work top down by layers. It begins by first identifying the top level requirements and suggesting top level design strategies for those, then making these higher strategies the basis for a lower level set of requirements, and so on down to the lowest components. This approach is intended to ensure that R&M is designed in from the beginning rather than added later with difficulty to a completed design concept. The new R&M standard uses an innovative and effective top-down system design approach intended to effectively implement R&M
Reliability Analysis of Complex NASA Systems with Model-Based Engineering
Get PDFThe emergence of model-based engineering, with Model- Based Systems Engineering (MBSE) leading the way, is transforming design and analysis methodologies. The recognized benefits to systems development include moving from document-centric information systems and document-centric project communication to a model-centric environment in which control of design changes in the life cycles is facilitated. In addition, a single source of truth about the system, that is up-to-date in all respects of the design, becomes the authoritative source of data and information about the system. This promotes consistency and efficiency in regard to integration of the system elements as the design emerges and thereby may further optimize the design. Therefore Reliability Engineers (REs) supporting NASA missions must be integrated into model-based engineering to ensure the outputs of their analyses are relevant and value-needed to the design, development, and operational processes for failure risks assessment and communication
Supersonic Technology Concept Aeroplanes for Environmental Studies
Get PDFThe International Civil Aviation Organization is considering new environmental standards for future supersonic civil aircraft. NASA is supporting this effort by analyzing several notional, near-term supersonic transports. NASAs performance, noise, and exhaust emission predictions for these transports are being used to inform a larger study that will determine the global environmental and economic impact of adding supersonic aircraft to the fleet beginning this decade. A supersonic business jet with a maximum takeoff gross weight of 55 tonnes is the focus of this paper. A smaller business jet weighing 45 tonnes is also discussed. Both airplanes use supersonic engines derived from a common contemporary commercial subsonic turbofan core. Aircraft performance, airport-vicinity noise, and exhaust emissions are predicted using NASA tools. Also investigated are some of the anticipated behaviors and requirements of these aircraft in the commercial airspace. The sensitivity of noise to system uncertainties is presented and alternative engine studies are discussed