Engineering topics

Lucchitta, B. K.

Publications and source records attributed to Lucchitta, B. K..

At least 37 records · Page 2

NASA NTRS1987

Water and ice on Mars: Evidence from Valles Marineris

An important contribution to the volatile history of Mars comes from a study of Valles Marineris, where stereoimages and a 3-D view of the upper Martian crust permit unusual insights. The evidence that ground water and ice existed until relatively recently or still exist in the equatorial area comes from observations of landslides, wall rock, and dark volcanic vents. Valles Marineris landslides are different in efficiency from large catastrophic landslides on Earth. One explanation for the difference might be that the Martian slides are lubricated by water. A comparison of landslide speeds also suggests that the Martian slides contain water. That Valles Marineris wall rock contained water or ice is further suggested by its difference from the interior layered deposits. Faults and fault zones in Valles Marineris also shed light on the problem of water content in the walls. Because the main evidence for water and ice in the wall rock comes from slides, their time of emplacement is important. The slides in Valles Marineris date from the time of late eruptions of the Tharsis volcanoes and thus were emplaced after the major activity of Martian outflow channels.

Lucchitta, B. K.↗

NASA NTRS1985

Use of the synoptic view: Examples from Earth and other planets

Space technology has added the synoptic view to other techniques used in geomorphology. Synoptic views are provided by spacecraft images or by application of space technology to time-honored information systems. Examples of spacecraft images of Earth are LANDSAT, SEASAT, and the SIR (Shuttle Imaging Radar) series. Examples of applied space technologies include the digital conversion of topographic maps to shaded relief maps and digital correlation methods. From the study of other planets we have learned that synoptic views enable the deciphering of a planet's history: large features are identified and mapped before small ones; studies proceed from the general to the specific. On Earth, we generally recognize smaller features and study specific processes first, then extrapolate toward larger features and a general synthesis. With the advent of space images of Earth, perhaps the time is ripe to employ the methods used for other planets to the study of terrestrial geology and geomorphology. The following examples illustrate the use of regional-scale studies on Earth: the application of synoptic-view images in Antarctica, the use of digital methods and correlations of multiple data sets in regional studies, and some benefits to our understanding of terrestrial geology that have been obtained from analyses of other planets.

Lucchitta, B. K.↗

NASA NTRS1985

Valles Marineris Basin Beds: a Complex Story

High resolution stereoimages of the central Valles Marineris enabled detailed geologic mapping on Ophir and Candor Chasmata. Abundant light colored deposits, both layered and massive, fill the chasmata in this region. Units within these deposits were identified by their erosional characteristics and superposition and cross cutting relations. The Valles Marineris beds reflect a history of repeated faulting, volcanic eruptions, and deposition and erosion, resulting in stratigraphic sequences with several unconformities. Because of the preponderance of apparent volcanic deposits inside the troughs, the chasmata may not be simple grabens, but rather giant volcano tectonic depressions. Major events in chasmata development are examined.

Lucchitta, B. K.↗

NASA NTRS1985

The Galilean Satellite Geological Mapping Program, 1984

About 40 investigators from various universities, research institutes, and government offices in the United States, England, Germany, and Italy are compiling maps of the Galilean satellites. All maps are at a scale of 1:5 million except for three of the Io maps, where high resolution pictures permit compilation of selected areas at larger scales. Guidelines for mapping Ganymede are discussed.

Lucchitta, B. K.↗

NASA NTRS1985

Geology of the Ganymede Quadrangle Jg7

The western half of Ganymede quadrangle Jg7 is covered by Voyager 2 images with resolution of .5 to 5 km/pixel. The imaged area includes dark terrain in the north underlying the southeastern part of Galileo Regio, and light terrain in the south underlying the southeastern extension of Uruk Sulcus. Several slivers and wedges of dark terrain occur within the light areas. Numerous craters are present, as well as three large palimsests (crater scars with little topographic expression) in the dark terrain and a basin in the light terrain. The boundary between dark and light materials on the south side of Galileo Regio is locally marked by a scarp that faces the light terrain. The scarp truncates several craters. The truncation and rotation of structures suggest that light material grew at the expense of dark material, and that the destruction, except for minor pivoting, was essentially in situ. The composition and structural properties of the palimsests and craters are examined.

Lucchitta, B. K.↗

NASA NTRS1984

Volcanism in the Valles Marineris

Tectoism in the Valles Marineris appears to have been accompanied by volcanism. The proposed volcanic features, though probably contemporaneous with the gigantic ones in the Tharsis area, are composed of small, mafic and, possibly, somewhat larger felsic flows. The size of these features is similar to that of volcanic flows on the Earth.

Lucchitta, B. K.↗

NASA NTRS1984

Dark streaks on talus slopes, Mars

High-resolution pictures of talus slopes on Mars show small, dark streaks that characteristically widen downward. These streaks are different from the thin and even streaks of various albedos that stream from cliffs on talus slopes, but gradations between the two streak types occur and not all streaks can be classified with confidence. In order to study the nature and origin of the small, widening, dark streaks, all Viking pictures with a resolution of less than 100 m/pixel were surveyed. To date several hundred streaks were located, but only few are of high enough resolution to be confidently identified as widening downwards. The approximate dimensions of the streaks were measured and their shapes, numbers, position, and spacing on slopes were noted. They were plotted on a topographic map, and their relation to topography, geologic units, and regions of distinct thermal inertia and albedo were studied. Also noted was the season at which images containing streaks were acquired and the direction of illumination. Albedo measurements are in progress. Several streaks can be seen stereoscopically, but none are observed on color images. The observation of small dark streaks on talus slopes on Mars is compatible with an interpretation of their origin as eruptions of small masses of wet debris in places where steep walls intersect aquifers or where seasonal equatorial warming permits the local melting of ground ice.

Ferguson, H. M.↗

NASA NTRS1984

Small-scale polygons on Mars

Polygonal-fracture patterns on the martian surface were discovered on Viking Orbiter images. The polygons are 2-20 km in diameter, much larger than those of known patterned ground on Earth. New observations show, however, that polygons exist on Mars that have diameters similar to those of ice-wedge polygons on Earth (generally a few meters to more than 100 m). Various explanations for the origin of these crustal features are examined; seasonal desiccation and thermal-contraction cracking in ice-rich ground. It is difficult to ascertain whether the polygons are forming today or are relics from the past. The crispness of some crack suggests a recent origin. On the other hand the absence of upturned edges (indicating actively forming ice wedges), the locally disintegrating ground, and a few possible superposed rayed craters indicate that the polygons are not forming at the present.

Lucchitta, B. K.↗

NASA NTRS1984

The Galilean Satellite Geological Mapping Program, 1983

The Galilean Satellite Geological Mapping Program was established to illuminate detailed geologic relations on the four large satellites of Jupiter. The program involves about 40 investigators from various universities, reseach institutes, and government offices in the United Sttes, England, Germany, and Italy. A total of 24 researchers have been assigned to map 10 quadrangles on Ganymede, 15 to map 6 quadrangles on Io, and 3 to map 2 quadrangles on Europa. All maps are at a scale of 1:5 million except for three of the Io maps, where high-resolution pictures permitted compilation of selected areas at larger scales.

Lucchitta, B. K.↗

NASA NTRS1984

Ice and debris in the fretted terrain, Mars

Viking moderate and high resolution images along the northern highland margin have been monoscopically and stereoscopically examined in order to study the development of fretted terrain. Young debris aprons around mesas and debris in tributary channels create typical fretted morphologies identical to ancient fretted morphologies. This suggests that the debris-apron process operating relatively recently also shaped the fretted terrain of the past. The debris aprons were lubricated by interstitial ice derived from ground ice. Abundant collapse features suggest that ground ice existed and may have flowed in places. The fretting process has been active for a long period and may be active today. The location of debris aprons in two latitudinal belts may be controlled by atmospheric conditions that permit ice in the region to remain in the ground below depths of about one meter and temperatures warm enough for ice to flow.

Lucchitta, B. K.↗

NASA NTRS1983

Chryse basin channels - Low-gradients and ponded flows

The analysis and construction of approximate channel floor longitudinal gradients from 26 radar elevation profiles at four latitudinal channel crossings show that the outflow channels of the Lunae Planum and Chryse Basin have much lower values than those of the U.S. Geological Survey's topographic map. In order to account for the movement of fluids to the north, it is proposed that ponding from local runoff occurred before channel transition along the course of Simud and Tiu Valles. The lakes eventually overflowed, drainages became integrated, and headward erosion reached interfluves, thereby forming the present channel configurations. The ponding and the flooding following it, which had sufficient head to move fluids across nearly level gradients, would have occurred during a period when the climate allowed the surface runoff of fluids and standing bodies of water.

Lucchitta, B. K.↗

NASA NTRS1982

Ice sculpture in the Martian outflow channels

Viking Orbiter and terrestrial satellite images are examined at similar resolution to compare features of the Martian outflow channels with features produced by the movement of ice on earth, and many resemblances are found. These include the anastomoses, sinuosities, and U-shaped cross profiles of valleys; hanging valleys; linear scour marks on valley walls; grooves and ridges on valley floors; and the streamlining of bedrock highs. Attention is given to the question whether ice could have moved in the Martian environment. It is envisaged that springs or small catastrophic outbursts discharged fluids from structural outlets or chaotic terrains. These fluids built icings that may have grown into substantial masses and eventually flowed like glaciers down preexisting valleys. An alternative is that the fluids formed rivers or floods that in turn formed ice jams and consolidated into icy masses in places where obstacles blocked their flow.

Lucchitta, B. K.↗

NASA NTRS1982

Structures on Europa

Four classes of lineation patterns have been identified on Europa in the area covered by high-resolution Voyager 2 images. These include dark, wedge-shaped bands in the west-central part of the area; triple bands associated with diagonally trending, global lineations; gray concentric curvilinear bands in the southeastern part; and ridges near the terminator. The major structures appear to have been formed by tidal forces centered on the axis pointing toward Jupiter, but variations in the detail of the structural patterns may have been caused by internal forces. The older strain patterns tend to be rejuvenated by younger fractures. The most persistent rejuvenated strain patterns are the global diagonal fractures, probably formed by conjugate shear, and the straight and curvilinear fractures that apparently caused an early dichotomy in fracture patterns.

Lucchitta, B. K.↗

NASA NTRS1982

The geology of Ganymede

A broad outline of the geologic history of Ganymede is presented, obtained from a first attempt to map the geology on a global scale and to interpret the characteristics of the observed geologic units. Features of the ancient cratered terrain such as craters and palimpsests, furrows and troughs, are discussed. The grooved terrain is described, including its sulci and cells, and the age relation of these units is considered along with the structure and origin of this terrain. The Gilgamesh Basin and Western Equatorial Basin in the post grooved terrain are treated, as are the bright and dark ray craters and the regolith. The development of all these regions and features is discussed in context. For the regolith, this includes the effect of water migration, sputtering, and thermal annealing. The histories of the ancient cratered terrain, the grooved terrain, and the post grooved terrain are presented.

Shoemaker, E. M.↗

NASA NTRS1982

The geology of Europa

The map units and lineations of Europa are detailed, and the geologic processes, and history, and thick and thin ice models of the satellite are discussed. It is concluded that Europa lacks evidence of a horizontally stratified crust; the geology appears characterized by disruption of the crust and intrusions into an icy shell. The surface consists of plains and mottled terrain, the former being older. Numerous straight and curved lineations, streaks, stripes, and bands cross EuropA's surface on a global and surface scale. Most lineations appear related to fractures in the crust. Five fresh craters in the 10 to 30 km diameter range are visible. The dark spots, stripes, and bands that appear to have replaced sections of the crust suggest that material was transported to the surface from the subjacent silicate lithosphere. The apparent low density of craters superposed on Europa's surface suggests that the surface is about 100 million years old.

Lucchitta, B. K.↗

NASA NTRS1981

Did ice streams carve Martian outflow channels

Outflow channels on Mars are long sinuous linear depressions that occur mostly in the equatorial area (+ or - 30 deg latitude). They differ from small valley networks by being larger and arising full-born from chaotic terrains. Outflow channels resemble terrestrial stream beds, and their origin has generally been attributed to water in catastrophic floods or mudflows. The problem of channel origin is examined here from the perspective of erosional characteristics and the resultant landforms created by former and present-day ice streams and glaciers on earth. From morphologic comparisons, an ice-stream origin seems equally well suited to explain the occurrences and form of the outflow channels on Mars, and in contrast with the hydraulic hypothesis, ice streams and ice sheets produce terrestrial features of the same scale as those observed on Mars.

Lucchitta, B. K.↗

NASA NTRS1981

Mars and earth - Comparison of cold-climate features

On earth, glacial and periglacial features are common in areas of cold climate. On Mars, the temperature of the present-day surface is appropriate for permafrost, and the presence of water is suspected from data relating to the outgassing of the planet, from remote-sensing measurements over the polar caps and elsewhere on the Martian surface, and from recognition of fluvial morphological features such as channels. These observations and the possibility that ice could be in equilibrium with the high latitudes north and south of + or - 40 deg latitude suggest that glacial and periglacial features should exist on the planet. Morphological studies based mainly on Viking pictures indicate many features that can be attributed to the action of ice. Among these features are extensive talus aprons; debris avalanches; flows that resemble glaciers or rock glaciers; ridges that look like moraines; various types of patterned ground, scalloped scarps, and chaotically collapsed terrain that could be attributed to thermokarst processes; and landforms that may reflect the interaction of volcanism and ice.

Lucchitta, B. K.↗

NASA NTRS1980

Grooved terrain on Ganymede

It is postulated that during a period in Ganymede's history when its lithosphere was thin, upwelling convection currents caused incipient rifting accompanied by intensive normal faulting. Where the rifting went to completion, crustal segments separated, spread apart locally, and sheared past one another. Subduction and compression may have occurred in places, but the evidence is inconclusive. The grooved terrain on Ganymede may therefore record an early phase of ice-plate tectonics that caused rifting and drifting of the icy lithosphere, but which, unlike silicate plate tectonics on earth, may have resulted in only minor vertical turnover. It is concluded that grooved terrain grew at the expense of cratered terrain, that cratered tracts were converted into grooved terrain in situ, and that vertical tectonism and shear movements dominated in the restructuring of Ganymede's surface.

Lucchitta, B. K.↗