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At least 415 records · Page 23

Cryogenic Origin for Mars Analog Carbonates in the Bockfjord Volcanic Complex Svalbard (Norway)

The Sverrefjell and Sigurdfjell eruptive centers in the Bockfjord Volcanic Complex (BVC) on Svalbard (Norway) formed by subglacial eruptions ca. 1 Ma ago. These eruptive centers carry ubiquitous magnesian carbonate deposits including dolomitemagnesite globules similar to those in the Martian meteorite ALH84001. Carbonates in mantle xenoliths are dominated by ALH84001 type carbonate globules that formed during quenching of CO2-rich mantle fluids. Lava hosted carbonates include ALH84001 type carbonate globules occurring throughout lava vesicles and microfractures and massive carbonate deposits associated with vertical volcanic vents. Massive carbonates include < or equal 5 cm thick magnesite deposits protruding downwards into clear blue ice within volcanic vents and carbonate cemented lava breccias associated with volcanic vents. Carbonate cements comprise layered deposits of calcite, dolomite, huntite, magnesite and aragonite associated with ALH84001 type carbonate globules lining lava vesicles. Combined Mossbauer, XRD and VNIR data show that breccia carbonate cements at Sverrefjell are analog to Comanche carbonates at Gusev crater.

Amundsen, H. E. F.↗

Origin of Sinuous Channels on the SW Apron of Ascraeus Mons and the Surrounding Plains, Mars

Ascraeus Mons is one of three large shield volcanoes located along a NE-SW trending lineament atop the Tharsis Bulge on Mars. Spacecraft images, beginning with Viking in the 1970 s, revealed that the SW rift apron of Ascraeus Mons is cut by numerous sinuous channels, many of which originate from large, elongated, bowl shaped amphitheaters known as the Ascraeus Chasmata. A number of these channels can be traced onto the flatter plains to the east of the rift apron. These features have been interpreted as either fluvial [1] or volcanic [2] in origin. Most recently, it has been shown that one of the longest channels on the Ascraeus rift apron appears to transition into a roofed-over lava channel or lava tube at its distal end, and thus the entire feature is likely of a volcanic origin [2]. In addition, field observations of recent lava flows on Hawaii have shown that lava is capable of producing features such as the complex braided and anastomosing channels and streamlined islands that are observed in the Ascraeus features [2].

Schierl, Z.↗

Emplacement Scenarios for Vallis Schroteri, Aristarchus Plateau, the Moon

The volcanic processes that formed Vallis Schr teri are not well understood. Vallis Schr teri, located on the Aristarchus Plateau, is the largest rille on the Moon, and it displays three key morphologic components: the Cobra Head, the 155-km-long primary rille, and the 240-km-long inner rille. Observations of terrestrial eruptions are applied here to help explain the morphologic relationships observed for Vallis Schr teri. The Cobra Head, a 10-km-wide source vent surrounded by a 35-kmdiameter and 900-m-high low shield, might have been constructed from fl ows, spatter, and pyroclastic deposits erupted during lava fountain events, similar to the early stages of the vent at Pu u O o in Hawaii and the fi nal morphology of Bandera crater, a cinder cone in New Mexico. The vent fed an initial sheet fl ow controlled by preeruption topography. A channel formed within this sheet fl ow was the foundation for the primary rille, which deepened through construction and thermomechanical erosion by lava. The inner rille is confi ned to the fl at fl oor of the primary rille and is characterized by tight gooseneck meanders. This rille crosscuts the distal scarp of the primary rille and extends toward Oceanus Procellarum. This enigmatic relationship can be explained through backup, overfl ow, and diversion of the lava into a new rille that eroded into the margin of the primary rille. Similar backup, overfl ow, and redirection of the lava fl ow were observed during the 1984 Mauna Loa eruption in Hawaii. Analysis of the fi nal morphology of lunar rilles provides key information about lunar volcanic processes and insight into the local stratigraphy.

Garry, W. Brent↗

Pyroclastic Deposits in the Floor-fractured Crater Alphonsus

Alphonsus, the 118 km diameter floor-fractured crater, is located immediately east of Mare Nubium. Eleven pyroclastic deposits have been identified on the crater's floor. Early telescopic spectra suggest that the floor of Alphonsus is noritic, and that the pyroclastic deposits contain mixtures of floor material and a juvenile component including basaltic glass. Head and Wilson contend that Nubium lavas intruded the breccia zone beneath Alphonsus, forming dikes and fractures on the crater floor. In this model, the magma ascended to the level of the mare but cooled underground, and a portion broke thru to the surface in vulcanian (explosive) eruptions. Alternatively, the erupted material could be from a source unrelated to the mare, in the style of regional pyroclastic deposits. High-resolution images and spectroscopy from the Moon Mineralogy Mapper (M3), Diviner Lunar Radiometer, and Lunar Reconnaissance Orbiter Camera Narrow Angle Camera (NAC) provide data to test these formation models. Spectra from M3 confirm that the crater floor is primarily composed of noritic material, and that the Nubium lavas are basaltic. Spectra from the three largest pyroclastic deposits in Alphonsus are consistent with a minor low- Ca pyroxene component in a glass-rich matrix. The centers of the 2 micron absorption bands have wavelengths too short to be of the same origin as the Nubium basalts. Diviner Christiansen feature (CF) values were used to estimate FeO abundances for the crater floor, Nubium soil, and pyroclastic deposits. The estimated abundance for the crater floor (7.5 +/- 1.4 wt.%) is within the range of FeO values for Apollo norite samples. However, the estimated FeO abundance for Nubium soil (13.4 +/- 1.4 wt.%) is lower than those measured in most mare samples. The difference may reflect contamination of the mare soil by highland ejecta. The Diviner-derived FeO abundance for the western pyroclastic deposit is 13.8 +/- 3.3 wt.%. This is lower than the values for mare soil samples, but within the range of analyzed pyroclastic glasses. The NAC images of the pyroclastic vents highlight their bright wall materials. The M3 spectra of the southeastern vent indicate that this bright material is noritic, likely crater floor material exposed by explosive eruption. These observations address the hypothesis that Nubium lavas intruded the fracture network beneath Alphonsus, leading to localized vulcanian-style eruptions. This model implies that the eruption products should be dominated by crystalline basalt fragments similar in elemental composition and mineralogy to mare lavas. The bright noritic material exposed in the vent walls is consistent with explosive eruptions. The estimated FeO abundances for the pyroclastic deposits are too low to be consistent with FeO abundances measured in mare basalts, but are within the range of pyroclastic glass samples. The visible- to near-infrared (VIS-NIR) spectra of the pyroclastic deposits and Nubium soils are significantly different, suggesting that the pyroclastics are unrelated to the mare basalts. The pyroclastic spectra are consistent with Fe-bearing glass plus small amounts of noritic wall rock. Similar glassy materials dominate regional pyroclastic deposits, suggesting a deep source for the pyroclastics observed in Alphonsus.

Allen, Carlton C.↗

Geologic Investigations Spurred by Analog Testing at the 7504 Cone-SP Mountain Area of the San Francisco Volcanic Field

The SP Mountain area of the San Francisco Volcanic Field, AZ, has been used as an analog mission development site for NASA since 1998. This area consists of basaltic cinder cones, lava flows and maar craters that have been active since mid-Miocene, with the youngest events occurring within the last 10,000 years. The area has been used because its geologic and topographic resemblance to lunar and Martian terrains provides an ideal venue for testing hardware and science operations practices that might be employed on planetary surfaces, as well as training astronauts in field geology. Analog operations have often led to insights that spurred new scientific investigations. Most recently, an investigation of the 7504 cone was initiated due to perceptions that Apollo-style traverse plans executed during the Desert RATS 2010 mission had characterized the area incorrectly, leading to concerns that the Apollo traverse planning process was scientifically flawed. This investigation revealed a complex history of fissure eruptions of lava and cinders, cinder cone development, a cone-fill-and-spill episode, extensive rheomorphic lava flow initiation and emplacement, and cone sector collapse that led to a final lava flow. This history was not discernible on pre-RATS mission photogeology, although independent analysis of RATS 2010 data and samples develped a "75% complete solution" that validated the pre-RATS mission planning and Apollo traverse planning and execution. The study also pointed out that the development of scientific knowledge with time in a given field area is not linear, but may follow a functional form that rises steeply in the early period of an investigation but flattens out in the later period, asymptotically approaching a theoretical "complete knowledge" point that probably cannot be achieved. This implies that future human missions must be prepared to shift geographic areas of investigation regularly if significant science returns are to be forthcoming.

Eppler, Dean B.↗

Lunar Advanced Volatile Analysis Integration and Testing

The Regolith and Environment Science Oxygen and Lunar Volatile Extraction (RESOLVE) payload is part of Resource Prospector (RP) along with a rover and a lander that are expected to launch in 2020. RP will identify volatile elements that may be combined and collected to be used for fuel, air, and water in order to enable deeper space exploration. The Resource Prospector mission is a key part of In-Situ Resource Utilization (ISRU). The demand for this method of utilizing resources at the site of exploration is increasing due to the cost of resupply missions and deep space exploration goals. The RESOLVE payload includes the Lunar Advanced Volatile Analysis (LAVA) subsystem. The main instrument used to identify the volatiles evolved from the lunar regolith is the Gas Chromatograph-Mass Spectrometer (GC-MS). LAVA analyzes the volatiles emitted from the Oxygen and Volatile Extraction Node (OVEN) Subsystem. The objective of OVEN is to obtain, weigh, heat and transfer evolved gases to LAVA through the connection between the two subsystems called the LOVEN line. This paper highlights the work completed during a ten week internship that involved the integration, testing, data analysis, and procedure documentation of two candidate mass spectrometers for the LAVA subsystem in order to aid in determining which model to use for flight. Additionally, the examination of data from the integrated Resource Prospector '15 (RP' 15) field test will be presented in order to characterize the amount of water detected from water doped regolith samples.

In-Situ Resource Utilization↗

Evidence for Dry Carbonatite Metasomatism in the Oceanic Lithosphere from Peridotite Xenoliths of Samoa and Lanzarote

Water in Earth’s mantle affects processes like magmatism and plate tectonics. Experiments show that CO2-rich fluids lower the water solubility in olivine, implying that CO2-rich melts/fluids may dehydrate the lithosphere during metasomatism. To test this hypothesis, we report water concentrations (by polarized FTIR) of olivines, orthopyroxenes (OPX) and clinopyroxenes (CPX) from Savai’i (Samoa) and Lanzarote (Canary Islands) peridotite xenoliths with evidence of carbonatite metasomatism. Savai’i peridotites are highly depleted harzburgites and dunites with spinel Cr# (Cr/(Cr+Al)) ranging from 0.4 to 0.76 (estimated degree of melting: 191.5%). Strong Light Rare Earth Element (LREE) enrichments with Ti and Zr depletions in OPX and CO2-rich fluid inclusions (via Raman spectroscopy) are consistent with carbonatite metasomatism. Olivine, OPX and reconstructed bulk rock water concentrations (0.67-3.8, 17-89 and 4-26 ppm H2O, respectively) are low and show no apparent relationship with extent of carbonatite metasomatism. Calculated water concentrations of melts in equilibrium with Savai’i OPX (OPX/melt partitioning of water 0.0063 to 0.011) are, on average (0.540.32 wt% H2O), lower than host Samoan lavas (0.63 to 1.5 wt% H2O), despite the LREE enrichments in OPX. Lanzarote peridotites are also highly depleted (degree of melting from spinel Cr#: 171.8%).Water concentrations are low in olivines (1.7-5.3 ppm H2O) and variable in pyroxenes (OPX: 42-103 ppm H2O; CPX: 105-301 ppm H2O), and show no apparent correlation with indicators of carbonatite metasomatism. Both Savai’i and Lanzarote peridotites show negative correlations between water and degree of melting (i.e. Mg/(Mg+Fe), Cr#), suggesting melt depletion rather than metasomatism may have influenced their water concentrations. Calculated water concentrations of melts in equilibrium with Lanzarote CPX (average 1.90.75 wt% H2O; CPX/melt partitioning of water 0.011 to 0.012) are similar to those for Western Canaries lavas (average 1.80.31 wt%; CPX/melt partitioning of water 0.016 to 0.021) inferred from their CPX phenocrysts. However, calculated Ce concentrations in such melts (352 to 378 ppm; CPX/melt partitioning of Ce 0.07) are an order of magnitude greater than the lavas, and similar to carbonatites. This leads to H2O/Ce to be an order of magnitude lower in the inferred melts (26 to 57) than estimates for Western Canary lavas (280150). These low H2O/Ce ratios may suggest H2O loss from CPX during ascent, but the lack of strong water diffusion gradients in Lanzarote minerals does not support this. Instead we hypothesize that carbonatite metasomatism resulted in greater enrichment of Ce over H2O. Assuming carbonatite magmas are water rich, this implies a lower partitioning of water between minerals and melts during metasomatism, as suggested by experiments. Our data suggests carbonatite metasomatism does not result in significant re-hydration of the lithosphere, in contrast to silicate metasomatism as previously observed in Hawaiian peridotites.

Ashley, Aaron↗

RESOLVE (Regolith & Environmental Science Oxygen & Lunar Volatile Extraction) Project

The RESOLVE Project is a lunar prospecting mission whose primary goal is to characterize water and other volatiles in lunar regolith. The Lunar Advanced Volatiles Analysis (LAVA) subsystem is comprised of a fluid subsystem that transports flow to the gas chromatograph - mass spectrometer (GC-MS) instruments that characterize volatiles and the Water Droplet Demonstration (WDD) that will capture and display water condensation in the gas stream. The LAVA Engineering Test Unit (ETU) is undergoing risk reduction testing this summer and fall within a vacuum chamber to understand and characterize component and integrated system performance. Testing of line heaters, printed circuit heaters, pressure transducers, temperature sensors, regulators, and valves in atmospheric and vacuum environments was done. Test procedures were developed to guide experimental tests and test reports to analyze and draw conclusions from the data. In addition, knowledge and experience was gained with preparing a vacuum chamber with fluid and electrical connections. Further testing will include integrated testing of the fluid subsystem with the gas supply system, near-infrared spectrometer for the Surge Tank (NIRST), WDD, Sample Delivery System, and GC-MS in the vacuum chamber. Since LAVA is a scientific subsystem, the near infrared spectrometer and GC-MS instruments will be tested during the ETU testing phase.

LAVA↗

Pathways Intern Report

During my time at NASA, I worked with the Granular Mechanics and Regolith Organization (GMRO), better known as Swamp Works. The goal of the lab is to find ways to utilize resources found after the astronaut or robot has landed on another planet or asteroid. This concept is known as in-situ resource utilization and it is critical to long term missions such as those to Mars. During my time here I worked on the Asteroid and Lava Tube Free Flyer project (ALTFF). A lava tube, such as the one shown in figure 1, is a long tear drop shaped cavern that is produced when molten lava tunnels through the surrounding rock creating large unground pathways. Before mining for resources on Mars or on asteroids, a sampling mission must be done to scout out useful resource deposits. ALTFF's goal is to provide a low cost, autonomous scout robot that can sample the surface and return to the mother ship or lander for further processing of the samples. The vehicle will be looking for water ice in the regolith that can be processed into either potable water, hydrogen and oxygen fuel, or a binder material for 3D printing. By using a low cost craft to sample, there is much less risk to the more expensive mother ship or lander. While my main task was the construction of a simulation environment to test control code in and the construction of the asteroid free flyer prototype, there were other tasks that I performed relating to the ALTFF project.

Pathways↗

Radiation and Nuclear Technology in Planetary Cave Environments

Many technological and environmental challenges must be resolved to enable successful lunar habitation and exploration, and to maximize scientific return. This presentation is intended as a preliminary discussion on three such areas of interest with the intent to identify likely areas of mutual benefit for collaboration and data sharing between the space nuclear and radiological disciplines with the planetary cave community. First is the previously identified and studied possible application of lunar lava tubes or pits to reduce the solar and cosmic radiation environment burden on crew health and hardware reliability. This is an area of continued interest, and should be kept in the forefront of discussion during the selection of sites for potential exploration or long-term habitation. In theory, the prospect of using existing morphology presents an enticing opportunity to reduce the requirements on landed mass or construction while also reducing dose or fluence of harmful natural radiation. However, such discussions should also include the practical implications of relocating habitation hardware and personnel from a landing site to a subsurface location. Inherent risks associated with landing in proximity to the relevant terrain must also be considered and weighed against those imposed by the natural radiation environment. Second is a discussion on the means by which a long-term habitation module or base of operations may be powered throughout the lunar day-night cycle. Fission surface power presents an opportunity to establish round-the-clock power in any lunar surface environment, including permanently shadowed regions where solar panels cannot operate, or in any other non-polar region where solar radiation is available for no more than two weeks per four-week cycle. Among the drawbacks of fission surface power is the need to either land and co-locate a heavy shield to minimize radiological consequences to personnel or equipment, land and operate construction equipment capable of restructuring the in-situ regolith to provide appropriate shielding, or to make use of existing topology features (e.g. craters or pits) to serve as pre-formed radiation barriers. A realistic assessment of the practicality of this third option should involve the selection of candidate features from existing surveys, and assess the effectiveness of the approach using modern radiation transport methodologies. Consideration must be made for the needs to reject waste heat in the thermal power conversion process, which typically requires the use of large area radiators. Energy must be exchanged from the reactor and power conversion system to such radiators, and the impacts on thermal efficiency and secondary scatter of nuclear radiation must be considered. Further consideration should be made for the implications of placement of a power source such that it does not sacrifice valuable scientific opportunity. Placement of a reactor is likely to thereafter prevent personnel access within that feature. Third is a discussion on the use of portable radioisotope power systems (RPS) within confined spaces, both with respect to the dose effects of emitted nuclear radiation and also performance associated with emitted thermal radiation. Radioisotope power systems provide a unique capability to power objects with no reliance upon solar radiance. However, their useable power production relies upon the flow of heat from ‘hot side’ (decaying radioisotope) to ‘cold side’ (radiators emitting heat to space). In the case of a confined volume in vacuum such as a lunar lava tube, that radiated energy will absorb into the wall, which is already above the ‘cold background’ temperature of dark space, and then gradually rises in temperature. That temperature rise, and its implications on availability of useable electrical power, will depend upon factors such as enclosure volume, thermal emissivity/absorptivity, and thermal conductivity through the depth of absorbing media. The advantages of nuclear technology may prove to enable unique scientific exploration opportunities, both above the lunar surface and below. In turn, the unique advantages of lunar lava tubes or pits may present unique opportunities to enhance the application of these technologies and to mitigate the effects of radiation from both natural and technological sources. A discussion on these pairings may prove to be valuable to all, in our endeavor to explore our neighboring worlds.

Radiation↗

Mariner 9 photographs of small-scale volcanic structures on Mars

Surface features on the flanks of Martian shield volcanoes photographed by Mariner 9 are identified as lava flow channels, rift zones, and partly collapsed lava tubes by comparisons with similar structures on the flanks of Mauna Loa shield volcano, Hawaii. From these identifications, the composition of the Martian lava flows is interpreted to be basaltic, with viscosities ranging from those of fluid pahoehoe to more viscous aa.

Greeley, R.↗

Moon - 'Ghost' craters formed during Mare filling.

This paper discusses formation of 'pathological' cases of crater morphology due to interaction of craters with molten lavas. Terrestrial observations of such a process are discussed. In lunar maria, a number of small impact craters (D less than 10 km) may have been covered by thin layers of fluid lavas, or formed in molten lava. Some specific lunar examples are discussed, including unusual shallow rings resembling experimental craters deformed by isostatic filling.

Cruikshank, D. P.↗

A model of the eastern portion of Schroeter's Valley

A relief model of the eastern portion of Schroter's Valley was completed using Lunar Orbiter, Apollo 15, and earth-based photography. The main results derived from this study are as follows: (1) the head of the valley is not a simple crater, but rather a slightly-widened section of the valley emanating from a shield, (2) the east side of the Cobra head is a very high peak (2.3 km above the surrounding plains) forming part of a broad shield with an average slope of 12 deg, and (3) both sides of the valley display a raised rim in the region measured. These and other observations indicate the valley was formed by fluid processes, probably lava, and that the valley may therefore be a lava drainage channel, the drained lava presumably underlying the more recent Oceanus Procellarum basalts.

Turner, R.↗

A model of the eastern portion of Schroeter's Valley

A relief model of the eastern portion of Schroeter's Valley has been completed using Lunar Orbiter, Apollo 15, and Earth-based photography. The main results derived from this study are as follows: (1) the head of the Valley (the Cobra head) is not a simple crater, but rather a slightly-widened section of the Valley emanating from a shield, (2) the east side of the Cobra head is a very high peak (2.3 km above the surrounding plains) forming part of a broad shield with an average slope of 12 deg, and (3) both sides of the Valley display a raised rim in the region measured. These and other observations indicate the Valley was formed by fluid processes, probably lava, and that the Valley may therefore be a lava drainage channel, the drained lava presumably underlying the more recent Oceanus Procellarum basalts.

Turner, R.↗

Mariner 9 photographs of small volcanic structures on Mars

Surface features on the flanks of martian shield volcanoes photographed by Mariner 9 are identified as lava flow channels, rift zones, and partly collapsed lava tubes by comparisons with similar structures on the flanks of Mauna Loa shield volcano, Hawaii. From these identification, the composition of the martian lava flows in interpreted to be basaltic, with viscosities ranging from those of fluid pahoehoe to more viscous aa.

Greeley, R.↗

An interpretation of volcanic and structural features of crater Aitken

Detailed observations from the study of Apollo 17 panoramic photography of the Aitken crater are reported which suggest that there has been significant late-stage compressional deformation of the crater and its adjacent highlands. A speculative interpretation of eruptive activity and drain-back events within Aitken is presented, which leads to the conclusion that hummocky topography within certain cones represents collapsed lava rather than extrusive domes. That is, eruptive activity within Aitken probably commenced with an explosive cone-building stage, followed by lava eruptions from cones and fissures, and ended with drain-back restricted to the relatively deep lava ponded in the vents.

Bryan, W. B.↗

Lunar volcanism in space and time

The role of lunar volcanism in the history of the moon is documented using lunar-orbit and earth-based data along with characterizations derived from Apollo and Luna sample-return missions. Characteristics of mare and highland volcanic features are described, Apollo and Luna results are discussed, and the characteristics of other mare deposits and of other highland features of possible volcanic origin are summarized. Major conclusions are that: (1) there is little unequivocal morphologic evidence for highland volcanism, (2) lunar mare lavas appear to have originated from depths of 100 to 500 km, (3) impact melting does not appear to have been a factor in the generation of mare lavas, (4) mare volcanism was characterized by massive outpourings of very fluid volatile-poor lava analogous to terrestrial flood basalts, (5) mare volcanism took place from 3.83 to about 2.5 billion years ago, (6) the preferential occurrence of mare deposits in large impact basins appears to be generically unrelated to basin formation, and (7) a thicker farside crust may be responsible for the distinctive nearside-farside asymmetry of mare deposits.

Head, J. W., III↗

On the origin of molecular 'handedness' in living systems

Elementary particle effects (beta-decay) provide only a weakly handed radiation in the biologically effective energy ranges. Global magnetic effects coupled to sunlight are randomized by paleomagnetic reversals. A persistent terrestrial handed bias at possible local biopoetic sites offers a more promising explanation for the origin of the 'handedness' of the molecules found among living systems on earth. Magnetite in lava flows maintains a handed bias for surface catalysis through many magnetic reversals. Indirect evidence for the hypothesis that magnetite contaminated with sulfur is a possible biopoetic site (Granick, 1957) has been provided by the molecular structure of ferredoxin - a single strand of the 14 primordial amino acids wrapped around an FeS core. Lava flows have been suggested as biopoetic sites by Fox (1964), since their temperature and chemical composition might allow for the rapid synthesis of prebiotic compounds at the surface of the primitive earth. The additional fact that magetite in lava flows also provides a persistent handed site for surface catalysis offers a further argument for the experimental investigation of this specific biopoetic environment.

Noyes, H. P.↗