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All sourcesNASA NTRSDOE OSTI
NASA NTRS2020

Overview and Initial Results of SAND-E: Semi-Autonomous Navigation for Detrital Environments

Unmanned 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 Thórisjökull 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.

Ewing, R. C.↗
NASA NTRS1986

Geochemical characters and tectonic evolution of the Chitradurga schist belt: An Archaean suture (?) of the Dharwar Craton, India

The Chitradurga schist belt extending for about 450 km in a NS direction and 2-50 km across, is one of the most prominent Archean (2.6 b.y.) tectonic features of the Indian Precambrian terrain, comprising about 2 to 10 km thick sequence of volcano sedimentary rocks. The basal unit of this belt is composed of an orthoquartzite-carbonate facies, unlike many other contemporary greentone belts of the Gondwana land which begin with a basal mafic-ultramafic sequence. Eighty percent of the belt is made up of detrital and chemogenic sediments, their succession commencing with a poorly preserved quartz pebble basal conglomerate and current bedded quartzites which, in turn, rest on tonalitic gneisses, the latter having been further remobilized with along the schist belt. Deposition of current bedded matue arenites indicte the existence of platformal conditions near the shore line. Polymictic graywacke conglomerates, graywackes, shales, phyllites, carbonates, BIFs (oxide, carbonate and sulfide) BMF's (Banded Maganese Formations) and cherts thus constitute the main sedimentary rocks of the belt. The polymicitic conglomerates contain debris of rocks of older greenstone sequences, as well as an abundant measure of folded quartzites, BIF's and gneissic fragments which represent earlier orogenies.

Naqvi, S. M.↗
NASA NTRS1997

Chicxulub Impact Ejecta in Belize

Chicxulub ejecta deposits in Belize provide the closest exposures of ejecta to the crater and the only exposures of proximal ejecta deposited in a terrestrial environment. A quarry on Albion Island in northern Belize exposes Late Cretaceous, possibly Maastrichtian, carbonate platform sediments that were folded, eroded, and subaerially weathered prior to the deposition of coarse ejecta from Chicxulub. These ejecta deposits are composed of a basal, about 1-m-thick clay and dolomite Spheroid Bed overlain by a about 15-m-thick coarse Diamictite Bed. Many and perhaps most of the clay spheroids are altered glass. Many dolomite spheroids have concentric layers and angular cores are probably of accretionary lapilli origin. A slight Ir concentration (111-152 ppt) was detected in the base of the Spheroid Bed. The Diamictite Bed contains about 10% altered glass, rare shocked quartz, 3-8 m diameter boulders and striated and polished cobbles, one with a penetrating rock chip that plastically deformed the cobble. Ejecta deposits extend to the surface at Albion and the maximum thickness in this area is not known. Ejecta deposits are exposed in several roadside quarries in the Cayo District of central Belize. The Late Cretaceous here is also represented by carbonate platform sediments. The upper surface of the carbonate platform is a highly irregular and extensively recrystallized horizon possibly representing deep karst weathering. Approximately 30 in of diamictite overlies this horizon with a texture similar to the Diamictite Bed at the Albion quarry, but with a more diverse lithology. In three locations the Cayo diamictites, contain red clay layers with abundant polished and striated limestone pebbles and cobbles called Pook's Pebbles, several of which have penetrating rock chips and ablated surfaces. We interpret the Albion Spheroid Bed as a deposit from the impact vapor plume and the Albion and Cayo diamictites as the result of a turbulent flow that contained debris derived from the ejecta curtain and local scouring. The polished, striated, and ablated Pook's Pebbles are interpreted as high altitude ballistic ejecta.

Ocampo, A.↗
NASA NTRS1981

MHD oxidant intermediate temperature ceramic heater study

The use of three types of directly fired ceramic heaters for preheating oxygen enriched air to an intermediate temperature of 1144K was investigated. The three types of ceramic heaters are: (1) a fixed bed, periodic flow ceramic brick regenerative heater; (2) a ceramic pebble regenerative heater. The heater design, performance and operating characteristics under conditions in which the particulate matter is not solidified are evaluated. A comparison and overall evaluation of the three types of ceramic heaters and temperature range determination at which the particulate matter in the MHD exhaust gas is estimated to be a dry powder are presented.

Carlson, A. W.↗
NASA NTRS2006

Geology of the Gusec cratered plains from the Spirit rover transverse

The cratered plains of Gusev traversed by Spirit are generally low-relief rocky plains dominated by impact and eolian processes. Ubiquitous shallow, soil-filled, circular depressions, called hollows, are modified impact craters. Rocks are dark, fine-grained basalts, and the upper 10 m of the cratered plains appears to be an impact-generated regolith developed over intact basalt flows. Systematic field observations across the cratered plains identified vesicular clasts and rare scoria similar to original lava flow tops, consistent with an upper inflated surface of lava flows with adjacent collapse depressions. Crater and hollow morphometry are consistent with most being secondaries. The size frequency distribution of rocks >0.1 m diameter generally follows exponential functions similar to other landing sites for total rock abundances of 5-35%. Systematic clast counts show that areas with higher rock abundance and more large rocks have higher thermal inertia. Plains with lower thermal inertia have fewer rocks and substantially more pebbles that are well sorted and evenly spaced, similar to a desert pavement or lag. Eolian bed forms (ripples and wind tails) have coarse surface lags, and many are dust covered and thus likely inactive. Deflation of the surface _5-25 cm likely exposed two-toned rocks and elevated ventifacts and transported fines into craters creating the hollows. This observed redistribution yields extremely slow average erosion rates of _0.03 nm/yr and argues for very little long-term net change of the surface and a dry and desiccating environment similar to today's since the Hesperian (or _3 Ga).

Spirit↗
NASA NTRS1992

Proximal impact deposits at the Cretaceous-Tertiary boundary in the Gulf of Mexico: a restudy of DSDP Leg 77 Sites 536 and 540

Restudy of Deep Sea Drilling Project Sites 536 and 540 in the southeast Gulf of Mexico gives evidence for a giant wave at Cretaceous-Tertiary boundary time. Five units are recognized: (1) Cenomanian limestone underlies a hiatus in which the five highest Cretaceous stages are missing, possibly because of catastrophic K-T erosion. (2) Pebbly mudstone, 45 m thick, represents a submarine landslide possibly of K-T age. (3) Current-bedded sandstone, more than 2.5 m thick, contains anomalous iridium, tektite glass, and shocked quartz; it is interpreted as ejecta from a nearby impact crater, reworked on the deep-sea floor by the resulting tsunami. (4) A 50-cm interval of calcareous mudstone containing small Cretaceous planktic foraminifera and the Ir peak is interpreted as the silt-size fraction of the Cretaceous material suspended by the impact-generated wave. (5) Calcareous mudstone with basal Tertiary forams and the uppermost tail of the Ir anomaly overlies the disturbed interval, dating the impact and wave event as K-T boundary age. Like Beloc in Haiti and Mimbral in Mexico, Sites 536 and 540 are consistent with a large K-T age impact at the nearby Chicxulub crater.

NASA Discipline Exobiology↗
NASA NTRS1980

Modes of sediment transport in channelized water flows with ramifications to the erosion of the Martian outflow channels

The paper discusses application to Martian water flows of the criteria that determine which grain-size ranges are transported as bed load, suspension, and wash load. The results show nearly all sand-sized material and finer would have been transported as wash load and that basalt pebbles and even cobbles could have been transported at rapid rates of suspension. An analysis of the threshold of sediment motion on Mars further indicates that the flows would have been highly competent, the larger flows having been able to transport boulder-sized material. Comparisons with terrestrial rivers which transport hyperconcentration levels of sediments suggest that the Martian water flows could have achieved sediment concentrations up to 70% in weight. Although it is possible that flows could have picked up enough sediment to convert to pseudolaminar mud flows, they probably remained at hyperconcentration levels and fully turbulent in flow character.

Komar, P. D.↗
NASA NTRS2007

Early Proterozoic (2.0 GA) Phosphorites from Pechenga Greenstone Belt and Their Origin

The period of 2500-2000 Ma is heralded by several other hallmark events, including onset and decline of the greatest positive excursion of Beta13Ccarb (Lomagundi-Jatuli Paradox), development of a significant seawater sulphate reservoir, abundant deposition of anomalously organic matter (OM)-rich sediments, the oldest known significant petroleum deposits (Shunga Event), and the appearance of first known marine phosphorites at 2000 Ma as reported here. They occur as numerous rounded, soft-deformed, clasts in fine-pebble intra-formational conglomerates, forming two separate c. 200 m-thick turbidite fans within the 1000 m-thick OM- and sulphide-rich turbiditic greywackes of the Pilgujaervi Formation in the Pechenga Greenstrone Belt, NW Russia. Carbonate-fluorapatite is the main mineral in the phosphorite clasts. OM, framboidal and micronodular pyrite as well as inclusions of quartz and chlorite are additional components. Many clasts show microlayering with a variable degree of soft-deformation, implying that they were derived from non-lithified, bedded phosphorites. Numerous samples revealed diverse microbial microstructures interpreted as cyanobacterial mats consisting of filamentous (1-3 micrometer in diameter, 20 micrometers in length), coccoidal (0.8-1.0 micrometers) and ellipsoidal or rod-shaped microfossils (0.8 micrometers in diameter, around 2 micrometers in length) which morphologically resemble modern Microcoleus and Syphonophycus, Thiocapsa, and Rhabdoderma, respectively, reported from alkaline or saline environments. No principle differences have been found between microfossils described from Cambrian and Phanerozoic and the 2000 Ma phosphorites. The sequence of the early Palaeoproterozoic events which point to a significant oxidation of the hydrosphere, now including formation of phosphorites and change in the phosphorous cycle, mimics the sequence which was repeated once again at the Neoproterozoic-Cambrian transition, implying that oxidation of the terrestrial atmosphere-hydrosphere system experienced an irregular cyclic development.

Rozanov, A. Yu.↗