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At least 145 records · Page 8
All sourcesNASA NTRSDOE OSTI
DOE OSTI2025

Composition and Plume Gas Interaction Control Iron Fractional Solubility More Than Particle Size in Volcanic Ash: Implications for Fertilization of the North Atlantic

Deposition of volcanic ash is thought to impact marine biogeochemical cycling by adding soluble iron (Fe) to the surface ocean. The magnitude of this input is a function of the amount of ash deposited, the total Fe content in the ash, and ash‐derived Fe's fractional solubility. However, the relative importance of chemical composition, acidic processing by the volcanic plume, and ash particle size in determining solubility is unclear. We paired an aerosol leach meant to provide an upper limit for fractional Fe solubility with chemical analyses of ash from the Cumbre Vieja (CV) and La Soufrière eruptions, which both impacted the North Atlantic in 2021. Fe in the ash samples is <6% soluble, but Fe fractional solubility in CV ash is approximately triple that of La Soufrière ash. Compared to La Soufrière, a larger proportion of the Fe in CV ash is in silicate rather than oxide minerals, which release more soluble Fe. Elevated levels of surficial fluorine (F) also suggest that CV ash was subjected to a more fluorine‐rich eruption plume and underwent more acidic processing. Particle size does not appear to be a primary control on Fe release. We estimate that the CV eruption had a much larger impact on dissolved Fe (DFe) concentration in the surface ocean than the La Soufrière eruption because of differences in soluble Fe content and particle deposition velocity. These differences may help explain why some eruptions elicit a biological response in the ocean while others do not.

Elliott, Hope E. [Univ. of Miami, FL (United State↗
NASA NTRS2005

The Explorer's Guide to Impact Craters

Impact cratering is a fundamental geologic process of our solar system. It competes with other processes, such as plate tectonics, volcanism, fluvial, glacial and eolian activity, in shaping the surfaces of planetary bodies. In some cases, like the Moon and Mercury, impact craters are the dominant landform. On other planetary bodies impact craters are being continuously erased by the action of other geological processes, like volcanism on Io, erosion and plate tectonics on the Earth, tectonic and volcanic resurfacing on Venus, or ancient erosion periods on Mars. The study of crater populations is one of the principal tools for understanding the geologic history of a planetary surface. Among the general public, impact cratering has drawn wide attention through its portrayal in several Hollywood movies. Questions that are raised after watching these movies include: How do scientists learn about impact cratering? , and What information do impact craters provide in understanding the evolution of a planetary surface? Fundamental approaches used by scientists to learn about impact cratering include field work at known terrestrial craters, remote sensing studies of craters on various solid surfaces of solar system bodies, and theoretical and laboratory studies using the known physics of impact cratering.

Chuang, F.↗
NASA NTRS1978

Morphometric comparison of braided Martian channels and some braided terrestrial features

Large channels on the Martian surface have been variously attributed to erosional, volcanic, and tectonic processes. Morphometric information shows that large braided Martian channels and islands between those channels are similar in their dimensions to channels and islands of large braided fluvial features on earth. The information also suggests that braided fractures in solid materials are fundamentally different in morphometry from braided channels of earth and Mars. Braided tension fractures have characteristically low braiding indices and are much narrower than their irregularly shaped 'midchannel' islands. Terrestrial and Martian channels, in contrast, have high braiding indices, and they are wider than their streamlined midchannel islands. Braided volcanic features are known from the earth and the moon, but the absence of volcanic constructs near the large braided channels on Mars indicates that volcanic origin is unlikely. The morphometric information suggests that braided Martian channels are probably of fluvial origin.

Trevena, A. S.↗
NASA NTRSDate not supplied

The Project “Analogs for VENus’s GEologically Recent Surfaces” (AVENGERS): Unveiling Active Volcanism on Venus

The recently selected missions to Venus opened a new era for the exploration of the Earth’s hellish twin sister. One of the key questions that the selected missions to Venus will address is whether the planet is volcanically active. The identification of ongoing volcanic activity on Venus can indeed unveil important clues on the geologic evolution of the planet, also helping us to better understand how volcanic and atmospheric processes work on Earth, especially those related to the climate change produced by greenhouse gases. To fully contextualize the higher resolution datasets to be provided by the future missions to Venus, we need to be able to exploit the wealth of data to be produced in the best possible way. Different types of instruments will indeed perform unprecedent orbiting and in-situ investigations of the surface and subsurface of Venus. To this regard, the Project “Analogs for VENus’s GEologically Recent Surfaces” (AVENGERS) aims to build a comprehensive database of Terrestrial active volcanoes which may act as suitable analogs for identifying ongoing volcanic activity on Venus. To do this, the project AVENGERS will combine the implementation of terrestrial orbiter radar data analysis techniques (i.e., radar interferometry) with infrared and laboratory analyses of lava flow samples from Terrestrial active volcanoes. As a first suitable analog of the Project AVENGERS, we selected Mount Etna in Sicily for a direct comparison with potentially active volcanic structures of Venus, and with Idunn Mons, one of the most promising possibly active volcanoes of Venus. Given its composite nature, Mount Etna offers the opportunity to identify and study multiple types of eruptive products (both effusive and explosive) from the analysis of high-resolution radar images. The frequent eruptions characterizing this volcano will also allow to test techniques of radar interferometry. Moreover, its ease of access facilitates geologic field trips and in-situ investigations with related sample retrieving. Ongoing infrared laboratory analysis on several altered and unaltered samples retrieved by Mount Etna will help to distinguish spectral signatures of fresh vs weathered volcanic deposits.

P. D’Incecco↗
NASA NTRS1976

Vulcanism, mercury-sensitized photo-reactions and abiogenetic synthesis - A theoretical treatment

Attention is called to the photodynamic and thermodynamic properties of Periodic Group IIb elements, most notably Hg, as they relate to ultra-violet sensitization in organic chemical reactions. The energy levels of 6 1P1 and 6 3P1 resonance states and the high vapor pressure (greater than 0.001 mm) of the metal at temperatures as low as 293 K bring Hg with the range of bond dissociation energies in most organic molecules and many inorganics. These capabilities considered together with recent evidence for Hg emission as a regular part of volcanic and geothermal processes provide the basis for a proposal that Hg-sensitized ultraviolet photo-reactions may have played a significant part in abiogenetic organic synthesis on the primative earth.

Siegel, S. M.↗
NASA NTRS1977

Basaltic volcanism in terrestrial planets

A prescription is presented of a 3-year experimental project designed to encourage a selected group of earth scientists to think on a Solar System scale rather than a terrestrial, lunar, or martian scale. Basaltic volcanism was the process selected because it manifests itself widely in the inner Solar System and because it seemed more cleanly separable from other geological problems than other processes considered. Studies in ten areas are to illuminate all aspects of the mechanics and chronology of the generation and eruption of basaltic lavas in the terrestrial planets. Attention is given to individual team reports related to the various areas.

Wood, J. A.↗
NASA NTRS1983

Hot spot heat transfer - Its application to Venus and implications to Venus and earth

Using a model that gives a relationship between surface elevation, lithospheric thickness, and heat flux, the hot spot heat loss mechanism is tested for Venus. The mechanism is found to readily explain the predicted heat loss of the planet with a modest number of hot spots (of the order of 35). Lithospheric thickness variations can explain approximately 93 percent of the mapped topography of Venus. Above a radius of 6053 km, additional compensation is required, and this can be effected by incorporating a variable thickness crust into the model. If it is assumed that the crust is generated on the crests of the hot spots, probably by processes associated with volcanism, the model is consistent with nearly 99 percent of the mapped topography of Venus. In addition, the model is basically consistent with available gravity data and interpretations that suggest compensated topography and great depths of compensation (100-1000 km) for the midlatitudes of the planet. It is thought that the approximately 1 percent of the topography not explained by hot spot crustal generation is compensated at a shallower depth primarily by variations in crustal thickness that are not directly related to hot spot volcanism.

Morgan, P.↗
NASA NTRS1984

SeaMARC 2 side-scan images of submarine volcanoes: Potential analogues for Venus

The Earth's surface beneath the oceans may be very similar, in terms of ambient pressures, to the surface of Venus. For that reason it is particularly important for geologists studying the surface of Venus to understand the processes which form features on the floors of the oceans. With the SeaMARC 2 seafloor mapping system, it is possible to view a swath of seafloor that is 10 km wide (about 6.2 mi). Side scan images of the Mariana region show that volcanoes of the island arc are more complicated than previously realized and that features of the fore-arc region, which resemble volcanoes morphologically, may result from processes other than volcanism. By comparing data obtained from the ocean floor with radar images of Venus, the geological evolution of that planet may be more fully understood.

Fryer, P.↗
NASA NTRS1985

Surfaces of Asteroids and Cometary Nuclei

The types of landforms and processes that may exist on cometary nuclei and asteroidal surfaces are investigated. Acknowledging that some asteroids may be cometary nuclei in disguise, asteroids are treated in this report as a simpler case than comets, owing to their more limited response to the state environment. Larger bodies (D 100 km) will not be discussed, even though they are recognized to be extremely important. This limitation permits only processes depending on exogenic phenomena to be considered (excluding processes such as volcanism on Vesta, for example), thus focusing discussion on the more unique aspects of these bodies, namely, their size and number.

Malin, M. C.↗
NASA NTRS1984

Venus - Volcanism and rift formation in Beta Regio

A new high-resolution radar image of Beta Regio, a Venus highland area, confirms the presence of a major tectonic rift system and associated volcanic activity. The lack of identifiable impact craters, together with the apparent superposition of the Theia Mons volcanic structure on the rift system, suggest that at least some of the volcanic activity occurred in relatively recent geologic time. The presence of topographically similar highland areas elsewhere on Venus (Aphrodite Terra, Dali Chasma, and Diana Chasma) suggests that rifting and volcanism are significant processes on Venus.

Campbell, D. B.↗
NASA NTRS1988

Diffuse scattering of radar on the surface of Venus - Origin and implications for the distribution of soils

Pioneer Venus (PV) altimeter data have been analyzed in order to study tectonic, volcanic, and degradational processes on Venus. Analysis of a corrected reflectivity data set in combination with the PV data indicates that no more than 5 percent of the Venusian surface is covered by soils more than several to tens of cm in depth. It is suggested that most regions of apparent low reflectivity are due to the presence of small roughness elements on the surface. These regions are correlated with tessera, and models show that the diffuse scatterers in the tessera are rock fragments originating as part of tectonic deformation of the surface.

Bindschadler, D. L.↗
NASA NTRS1990

Proceedings of the MEVTV Workshop on The Evolution of Magma Bodies on Mars

The workshop focused on many of the diverse approaches related to the evolution of magma bodies on Mars that have been pursued during the course of the Mars Evolution of Volcanism, Tectonism, and Volatiles (MEVTV) Program. Approximately 35 scientists from the Mars volcanology, petrology, geochemistry, and modeling communities attended. Segments of the meeting concentrated of laboratory analyses and investigations of SNC meteorites, the interpretation of Viking Orbiter and Lander datasets, and the interpretation of computer codes that model volcanic and tectonic processes on Mars. Abstracts of these reports are presented.

Mouginis-Mark, P.↗
NASA NTRS1991

Planetary geomorphology research: FY 1990-1991

Progress in the following research areas is discussed: (1) volatile ice sublimation in a simulated Martian polar environment; (2) a global synthesis of Venusian tectonics; (3) a summary of nearly a decade of field studies of eolian processes in cold volcanic deserts; and (4) a model for interpretation of Martian sediment distribution using Viking observations. Some conclusions from the research are presented.

Malin, M. C.↗
NASA NTRS1992

Ar-40 to Ar-39 dating of pseudotachylites from the Witwatersrand basin, South Africa, with implications for the formation of the Vredefort Dome

The formation of the Vredefort Dome, a structure in excess of 100 km in diameter and located in the approximate center of the Witwatersrand basin, is still the subject of lively geological controversy. It is widely accepted that its formation seems to have taken place in a single sudden event, herein referred to as the Vredefort event, accompanied by the release of gigantic amounts of energy. It is debated, however, whether this central event was an internal one, i.e., a cryptoexplosion triggered by volcanic or tectonic processes, or the impact of an extraterrestrial body. The results of this debate are presented.

Trieloff, M.↗
NASA NTRS2003

Mars: Updating Geologic Mapping Approaches and the Formal Stratigraphic Scheme

At the Fourth Mars Conference in 1989, Tanaka reviewed the stratigraphy and geologic history of Mars that had emerged based on systematic geologic mapping of the planet s surface using Viking data. This review looked at the stratigraphic column for Mars and assessed the global geologic history in terms of impact, fluvial, periglacial, aeolian, volcanic, and tectonic processes. Many significant new studies using Mars Global Surveyor (MGS) and now Mars Odyssey (MO) data are showing some important new insights and discoveries that are altering and deepening previous understandings. If we were to illustrate the current state of the science, we might compare it to a loose-leaf notebook in which pages are rapidly being added, removed, and rewritten, with plenty of room remaining. Much of the flux is due to new data, of course, but also much can be attributed to the re-examination of basic assumptions and approaches and our ability to employ ever more powerful computer techniques. Here, we will attempt to review, based on our experience, the areas where the most change seems to be occurring, what prospects we face in the immediate future, and where caution needs to be exercised.

K L Tanaka↗
NASA NTRS2004

ASE Floodwater Classifier Development for EO-1 Hyperion Imagery

The objective of this investigation is to develop a prototype floodwater detection algorithm for Hyperion imagery. It will be run autonomously onboard the EO-1 spacecraft under the Autonomous Sciencecraft Experiment (ASE). This effort resulted in the development of two classifiers for floodwater, one of several classifier types that have been developed and will be uploaded to EO-1 in early 2004 in order to detect change related to transient processes such as volcanism, flooding, and ice formation and retreat.

Ip, Felipe↗
NASA NTRS2004

Lunar and Planetary Science XXXV: Education

The session "Education" includes the following topics: 1) Convection, Magnetism, Orbital Resonances, Impacts, and Volcanism: Energies and Processes in the Solar System: Didactic Activities; 2) Knowledge Management in Aerospace-Education and Training Issues; 3) Creating Easy-to-Understand Planetary Maps; 4) Planetary Environment comparison in the Education of Astrobiology; and 5) Design and Construction of a Mechanism for the Orbital Resonances Simulation.

Source record↗
NASA NTRS2005

Monitoring Floods with NASA's ST6 Autonomous Sciencecraft Experiment: Implications on Planetary Exploration

NASA's New Millennium Program (NMP) Autonomous Sciencecraft Experiment (ASE) [1-3] has been successfully demonstrated in Earth-orbit. NASA has identified the development of an autonomously operating spacecraft as a necessity for an expanded program of missions exploring the Solar System. The versatile ASE spacecraft command and control, image formation, and science processing software was uploaded to the Earth Observer 1 (EO-1) spacecraft in early 2004 and has been undergoing onboard testing since May 2004 for the near real-time detection of surface modification related to transient geological and hydrological processes such as volcanism [4], ice formation and retreat [5], and flooding [6]. Space autonomy technology developed as part of ASE creates the new capability to autonomously detect, assess, react to, and monitor dynamic events such as flooding. Part of the challenge has been the difficulty to observe flooding in real time at sufficient temporal resolutions; more importantly, it is the large spatial extent of most drainage networks coupled with the size of the data sets necessary to be downlinked from satellites that make it difficult to monitor flooding from space. Below is a description of the algorithms (referred to as ASE Flood water Classifiers) used in tandem with the Hyperion spectrometer instrument on EO-1 to identify flooding and some of the test results.

Ip, Felipe↗