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At least 163 records · Page 9
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NASA NTRSDate not supplied

Future Lunar Geophysical Mission Opportunities Including the Lunar Geophysical Network, Artemis and CLPS

In the next few years, several opportunities are underway to take new geophysical observations of the Moon including geodetic and seismic. NASA’s novel Commercial Lunar Payload Services (CLPS) program seeks to acquire delivery services from 14 US companies. Nine funded task orders have been selected with payloads from multiple disciplines. Here we review the upcoming geophysical CLPS payloads and their measurement objectives then we provide a review of the Lunar Geophysical Network mission in development for New Frontiers 5. The Lunar Geophysical Network (LGN) mission is proposed to land on the Moon in the early 2030’s and deploy packages at four locations to enable continuous geophysical measurements for a minimum of 6 and a goal of 10 years. Returning to the lunar surface with a long-lived geophysical network is a key next step to advance lunar and planetary science. LGN will greatly expand our primarily Apollo-based knowledge of the deep lunar interior by identifying and characterizing mantle melt layers, as well as core size and state. To meet the mission objectives, the instrument suite provides complementary seismic, geodetic, heat flow, and electromagnetic (EM) observations. We discuss the network landing site requirements and provide example sites that meet these requirements. Landing sites include the P-5 region within the Procellarum KREEP Terrane (PKT; (lat:15˚; lon:-35˚), Schickard basin (lat:-44.3˚; lon:-55.1˚), Crisium basin (lat:18.5˚; lon:61.8˚), and the farside Korolev basin (lat:-2.4˚; lon:-159.3˚) (Figure 1). Network optimization considers the best locations to observe seismic core phases, e.g., ScS and PKP. Ray path density and proximity to young fault scarps are also analyzed to provide increased opportunities for seismic observations. Geodetic constraints from laser ranging require the LGN to have at least three nearside stations at maximum limb distances. Heat flow and EM measurements should be obtained away from terrane boundaries and from magnetic anomalies at locations representative of global trends. In our recent paper, an in-depth case study is provided for Mare Crisium. We also discuss the consequences for scientific return of less-than-optimal locations or number of stations.

Moons↗
NASA NTRS1984

High precision measurements in crustal dynamic studies

The development of high-precision instrumentation for monitoring benchmark stability and evaluating coseismic strain and tilt signals is reviewed. Laser strainmeter and tilt observations are presented. Examples of coseismic deformation in several geographic locations are given. Evidence suggests that the Earth undergoes elastic response to abrupt faulting.

Wyatt, F.↗
NASA NTRS1987

Kinematics at the intersection of the Garlock and Death Valley fault zones, California: Integration of TM data and field studies. LANDSAT TM investigation proposal TM-019

Processing and interpretation of Thematic Mapper (TM) data, extensive field work, and processing of SPOT data were continued. Results of these analyses led to the testing and rejecting of several of the geologic/tectonic hypotheses concerning the continuation of the Garlock Fault Zone (GFZ). It was determined that the Death Valley Fault Zone (DVFZ) is the major through-going feature, extending at least 60 km SW of the Avawatz Mountains. Two 5 km wide fault zones were identified and characterized in the Soda and Bristol Mountains, forming a continuous zone of NW trending faulting. Geophysical measurements indicate a buried connection between the Avawatz and the Soda Mountains Fault Zone. Future work will involve continued field work and mapping at key locations, further analyses of TM data, and conclusion of the project.

Abrams, Michael↗
NASA NTRS1991

Implications of convection in the moon and the terrestrial planets

A comprehensive review is made of the thermal chemical evolution of the moon and the terrestrial planets. New results are presented which were obtained for Venus by the Magellan Mission the efforts were concentrated on this planet. Alternative models were examined for the thermal structure of the lithosphere of Venus. The statistical distribution was studied of the locations of the coronae on Venus. Models were examined for the patterns of faulting around the coronae on Venus. A series was considered of viscous models for the development and relaxation of elevation anomalies on Venus. And rates were studied of solidification of volcanic flows on Venus. Both radiative and convective heat transfer were considered.

Turcotte, Donald L.↗
NASA NTRS1993

Radial basis function neural networks applied to NASA SSME data

This paper presents a brief report on the application of Radial Basis Function Neural Networks (RBFNN) to the prediction of sensor values for fault detection and diagnosis of the Space Shuttle's Main Engines (SSME). The location of the Radial Basis Function (RBF) node centers was determined with a K-means clustering algorithm. A neighborhood operation about these center points was used to determine the variances of the individual processing notes.

Wheeler, Kevin R.↗
NASA NTRS1989

Tectonics and volcanism in central Mexico - A Landsat Thematic Mapper perspective

Digitally enhanced Landsat Thematic Mapper (TM) images were used to map neotectonic deformation in central Mexico. This region has been studied for decades using a variety of geological and geophysical techniques, but synoptic mapping of neotectonic activity and major fault zones there, and an evaluation of their regional relationship to the character and location of volcanism were not previously possible until the application of synoptic, high resolution satellite imagery. Interpretation of the TM images shows that the tectonic deformation is closely linked in time and space to the dominantly calc-alkaline volcanics of the Mexican Volcanic Belt (MVB). The eruptive style and distribution of the volcanics is clearly related to the deformation resulting from relative motions of three large crustal blocks south of the MVB. Therefore, zones of weakness within the crust of central Mexico, which may be inherited from earlier episodes of deformation, are a principal factor controlling the oblique orientation of the MVB relative to the Acapulco Trench.

Johnson, C. A.↗
NASA NTRS1993

Ridge belt-related scarps and troughs: Compressional crustal bending on Venus

Cytherean ridge arcs resulted in crustal shortening in places with either the strongest compression or weakest surface layers. Arcuate scarps on or close to the edge of the ridge arcs were compressional fronts formed by overthrust over or subduction of adjacent lowland. These ridge arcs became wider due to the propagation of new ridge formation close to previous one(s). As this process repeated itself with time, the crust became thicker and the foreland was bent either due to the excess load, overthrust or subduction event. The Salme Dorsa arc measures 100 km in width and 600 km in length. It consists of a horseshoe-like set of ridges and grooves on a gently sloping lowland. The westward arcuate ridge belt indicates lateral compressional stresses and crustal deformation from SE against the southern Ishtar Terra foreland plain. The trough on the western side of the ridge belt and tensional grabens close to the crest of the bulge to the west of the trough are due to the crustal bending and indicate effects of the load and thrust. Compression and relative movement from southeast against and over the foreland planitia have resulted in ridge belt, trough and bulge formation. The load- and/or stress-induced bending of the uppermost crust allows some estimations of the uppermost elastic lithosphere thickness. Repeated folding and thrust faulting of surface layers due to compression are indicated by four more ridge belts located close to Salme Dorsa. The northeasternmost one has short ridges located in troughs. The west-opening arcuate ridge belt interlocks with the Salme Dorsa horseshoe.

Raitala, J.↗
NASA NTRS2009

Using Unmanned Aircraft Systems (UAS) for Remote Sensing: Airspace Access Challenges

Several areas of scientific interest have been identified that would significantly benefit from using Unmanned Aircraft Systems (UAS) for gathering remote sensing data. UAS are uniquely suited for applications that require long dwell times and/or in locations that are generally too dangerous for manned aircraft. Sea ice characterization, mapping of fault lines, hurricane monitoring, and satellite validation are some examples of applications that are benefited by the use of UAS. UAS are not without their challenges, however. Instruments must be automated and miniaturized, and be able to operate in extreme conditions (i.e. high altitude environments). However, because UAS currently lack a see-and-avoid capability, the greatest challenge is getting access to the airspace required to accomplish science missions. The ability for UAS to access airspace varies from country to country. This paper will give a brief overview of different UAS remote sensing applications, and will address general world airspace issues and challenges with a specific look at the United States.

Mulac, Brenda L.↗
NASA NTRS1995

Coseismic fault slip associated with the 1992 M(sub w) 6.1 Joshua Tree, California, earthquake: Implications for the Joshua Tree-Landers earthquake sequence

Coseismic surface deformation associated with the M(sub w) 6.1, April 23, 1992, Joshua Tree earthquake is well represented by estimates of geodetic monument displacements at 20 locations independently derived from Global Positioning System and trilateration measurements. The rms signal to noise ratio for these inferred displacements is 1.8 with near-fault displacement estimates exceeding 40 mm. In order to determine the long-wavelength distribution of slip over the plane of rupture, a Tikhonov regularization operator is applied to these estimates which minimizes stress variability subject to purely right-lateral slip and zero surface slip constraints. The resulting slip distribution yields a geodetic moment estimate of 1.7 x 10(exp 18) N m with corresponding maximum slip around 0.8 m and compares well with independent and complementary information including seismic moment and source time function estimates and main shock and aftershock locations. From empirical Green's functions analyses, a rupture duration of 5 s is obtained which implies a rupture radius of 6-8 km. Most of the inferred slip lies to the north of the hypocenter, consistent with northward rupture propagation. Stress drop estimates are in the range of 2-4 MPa. In addition, predicted Coulomb stress increases correlate remarkably well with the distribution of aftershock hypocenters; most of the aftershocks occur in areas for which the mainshock rupture produced stress increases larger than about 0.1 MPa. In contrast, predicted stress changes are near zero at the hypocenter of the M(sub w) 7.3, June 28, 1992, Landers earthquake which nucleated about 20 km beyond the northernmost edge of the Joshua Tree rupture. Based on aftershock migrations and the predicted static stress field, we speculate that redistribution of Joshua Tree-induced stress perturbations played a role in the spatio-temporal development of the earth sequence culminating in the Landers event.

Bennett, Richard A.↗
NASA NTRS2009

Using Decision Trees to Detect and Isolate Simulated Leaks in the J-2X Rocket Engine

The goal of this work was to use data-driven methods to automatically detect and isolate faults in the J-2X rocket engine. It was decided to use decision trees, since they tend to be easier to interpret than other data-driven methods. The decision tree algorithm automatically "learns" a decision tree by performing a search through the space of possible decision trees to find one that fits the training data. The particular decision tree algorithm used is known as C4.5. Simulated J-2X data from a high-fidelity simulator developed at Pratt & Whitney Rocketdyne and known as the Detailed Real-Time Model (DRTM) was used to "train" and test the decision tree. Fifty-six DRTM simulations were performed for this purpose, with different leak sizes, different leak locations, and different times of leak onset. To make the simulations as realistic as possible, they included simulated sensor noise, and included a gradual degradation in both fuel and oxidizer turbine efficiency. A decision tree was trained using 11 of these simulations, and tested using the remaining 45 simulations. In the training phase, the C4.5 algorithm was provided with labeled examples of data from nominal operation and data including leaks in each leak location. From the data, it "learned" a decision tree that can classify unseen data as having no leak or having a leak in one of the five leak locations. In the test phase, the decision tree produced very low false alarm rates and low missed detection rates on the unseen data. It had very good fault isolation rates for three of the five simulated leak locations, but it tended to confuse the remaining two locations, perhaps because a large leak at one of these two locations can look very similar to a small leak at the other location.

Schwabacher, Mark A.↗
NASA NTRS2011

Planetary Gearbox Fault Detection Using Vibration Separation Techniques

Studies were performed to demonstrate the capability to detect planetary gear and bearing faults in helicopter main-rotor transmissions. The work supported the Operations Support and Sustainment (OSST) program with the U.S. Army Aviation Applied Technology Directorate (AATD) and Bell Helicopter Textron. Vibration data from the OH-58C planetary system were collected on a healthy transmission as well as with various seeded-fault components. Planetary fault detection algorithms were used with the collected data to evaluate fault detection effectiveness. Planet gear tooth cracks and spalls were detectable using the vibration separation techniques. Sun gear tooth cracks were not discernibly detectable from the vibration separation process. Sun gear tooth spall defects were detectable. Ring gear tooth cracks were only clearly detectable by accelerometers located near the crack location or directly across from the crack. Enveloping provided an effective method for planet bearing inner- and outer-race spalling fault detection.

Lewicki, David G.↗
NASA NTRS1980

Elevation changes near the San Gabriel Fault, Southern California

Analysis of repeated leveling observations in the vicinity of the San Gabriel Fault in Southern California indicate subsidence immediately south of the Fault relative to points to the north, south and east. These observations were previously interpreted as reflecting tectonic motions associated with either the 'Palmdale Bulge' or with preseismic effects of the San Fernando earthquake. Relative subsidence between 1953 and 1964 reaches approximately 9 cm and extends over a distance of more than 20 km. Subsidence occurs directly above the Saugus aquifer and shows a temporal correlation with the history of water level decline within the aquifer. The degree of subsidence of individual benchmarks is roughly proportional to the product of aquifer thickness and water level decline at the location of the benchmarks. Thses observations strongly suggest that movements of the surface near the San Gabriel Fault, previously inferred to be of tectonic origin, actually result from near surface sediment compaction within the Saugus basin.

Reilinger, R.↗
NASA NTRS1984

Fault friction, regional stress, and crust-mantle coupling in southern California from finite element models

To determine the correct fault rheology of the Transverse Ranges area of California, a new finite element to represent faults and a mangle drag element are introduced into a set of 63 simulation models of anelastic crustal strain. It is shown that a slip rate weakening rheology for faults is not valid in California. Assuming that mantle drag effects on the crust's base are minimal, the optimal coefficient of friction in the seismogenic portion of the fault zones is 0.4-0.6 (less than Byerly's law assumed to apply elsewhere). Depending on how the southern California upper mantle seismic velocity anomaly is interpreted, model results are improved or degraded. It is found that the location of the mantle plate boundary is the most important secondary parameter, and that the best model is either a low-stress model (fault friction = 0.3) or a high-stress model (fault friction = 0.85), each of which has strong mantel drag. It is concluded that at least the fastest moving faults in southern California have a low friction coefficient (approximtely 0.3) because they contain low strength hydrated clay gouges throughout the low-temperature seismogenic zone.

Bird, P.↗
NASA NTRS1974

Geologic applications of ERTS images on the Colorado Plateau, Arizona

Three areas in central and northern Arizona centered on the (1) Verde Valley, (2) Coconino Plateau, and (3) Shivwits Plateau were studied using ERTS photography. Useful applications results include: (1) upgrading of the existing state geologic map of the Verde Valley region; (2) detection of long NW trending lineaments in the basalt cap SE of Flagstaff which may be favorable locations for drilling for new water supplies; (3) tracing of the Bright Angel and Butte faults to twice their previously known length and correlating the extensions with modern seismic events, showing these faults to be present-day earthquake hazards; (4) discovering and successfully drilling perched sandstone aquifers in the Kaibab Limestone on the Coconino Plateau; and (5) determining the relationship between the Shivwits lavas and the formation of the lower Grand Canyon and showing that the lavas should be an excellent aquifer, as yet untapped.

Goetz, A. F. H.↗
NASA NTRS1974

Geologic evaluation and applications of ERTS-1 imagery over Georgia

Satellite imagery and other remote sensing tools and techniques have provided a powerful tool to assist geologic research; significantly increased the mapping efficiency of field geologists; shown new lineaments associated with known shear and fault zones; delineated new structural features; provided a tool to reevaluate tectonic history; helped to locate potential ground-water sources and areas of aquifer recharge; defined areas of geologic hazards; shown areas of heavy siltation in major reservoirs; and, by close interval repetition, aided in monitoring surface mine reclamation activities and the environmental protection of the intricate marshland system. The Georgia Geological Survey has been engaged in regional mapping for the new state geologic map. ERTS-1 images enlarged to compatible mapping scales have increased field geologic mapping efficiency by at least 25%. There are a number of areas where data from ERTS-1 imagery has allowed a notably higher level of precision than has been available with any amount of field work on the ground.

Pickering, S. M.↗
NASA NTRS1974

On the origin of mascons and moonquakes

Hypotheses are proposed for the origin of mascons and moonquakes. It is noted that a horizontal transfer of magma is required to explain the mascons and that a basin which can fill with lava to a depth of about 20 km is necessary before mascon formation is possible. It is shown that hydrostatic equilibrium theories can account for the excess filling of lava in circular maria and that mascons will result when this process occurs in the presence of a thick rigid lithosphere. It is postulated that a cylindrical fault system extends through the lithosphere and surrounds the circular maria. In this case, the release of potential energy through the fault system would be adequate to explain moonquakes, their properties, and the clustering of the locations of lunar transient events around the circular maria.

Runcorn, S. K.↗
NASA NTRS1993

Geology of Biblis Patera, Ulysses Patera, and Jovis Tholus, Mars

There are a variety of constructional volcanic features in Tharsis. These features range from Olympus Mons and the Tharsis Montes shields, to the small low shields and fissure eruptions that characterize much of the volcanic plains, to the smaller volcanic constructs in the northeast and western parts of Tharsis. I describe the geology of the western group, which includes Biblis Patera, Ulysses Patera, and Jovis Tholus. Each of these volcanoes has had a unique, and complex geologic history. Biblis Patera is located at 2.3 deg. N, 123.8 deg. The volcano is elongate in a northwesterly direction and has a large, faulted caldera complex. The flanks of the volcano and adjacent plains are characterized by lava flows, northwest-trending graben and troughs, and caldera-concentric graben and troughs. Biblis Patera is approximately 66 x 127 km with an oval 51 x 56 km caldera; the summit elevation is approximately 2 km above the surrounding plains. The constrcut has an estimated volume of 8-22 x 10(exp 3) cu km. Ulysses Patera is located at 2.7 deg. N, 121.3 deg. W and stands approx. 2-3 km above the surrounding plain; flank slopes are approximately 7 deg. to 12 deg. The caldera floor is quite deep, lying 1.8 to 2.2 km below the caldera rim. The caldera has a void volume of approximately 5000 cu km, the total solid mass volume of the volcano is 7-16 x 10(exp 3) cu km. Jovis Tholus is centered at 18.3 deg N; 117.5 deg W; it is a low relief, volcano with gentle flank slopes of between 3 and 8 deg. The construct is dominated by a series of inset calderas which make up the largest fraction of the area. The caldera complex is offset to the southwest side. Total shield dimensions are approximately 77 km (e-wt) by 62 km (n-s); the caldera complex is approximately 44 x 34 km. The shield is embayed on all sides by younger Amazonian age volcanics. Total relief, relative to the surrounding plains, is probably approximately 2 km. The total volume of Jovis Tholus is estimated to be approximately 2-5 x 10(exp 3) cu km.

Plescia, J. B.↗
NASA NTRS1993

Emplacement of multiple flow units on very shallow slopes, east Kawelu Planitia flow field, Venus

Lobate flows with variable radar brightness occur at several locations on Venus. Here we present preliminary mapping results for a lava flow field on the eastern side of Kawelu Planitia, centered at approximately 41 deg N, 251 deg E. Numerous individual flows of varying brightness can be traced for up to 400 km at this location. Megallan image F-MIDRP.40N251;1 contains two major flow complexes as well as a distinct minor flow field associated with a volcanic dome. The southern flow field (unit F) changes from radar dark to radar bright in a convex arc from west to east. The flow path is diverted by a ridge system (unit B) and associated N-S faulted zone (unit A) evident in the Magellan altimetry data. The 130-km-long radar-bright flow field located at 41.5 deg N and 249-250 deg E is comprised of a narrow, channeled flow (unit E) overlying an intermediate brightness flow (unit D), all of which appears to emanate from a solitary dome at 249 deg E. The southern lobe of unit E disappears under a broad leveed channel (41.3 deg N, 250.1 deg E) in unit 5, only to reappear south of the unit 5 boundary. The source of this largest flow field is not evident, but could be associated with the region of small domes west of the F-MIDRP image (centered at 41 deg N, 246 deg E). Another possible source is the fractured area south of unit C. The flow complex is clearly a conglomeration of many flow episodes, not necessarily from a single source.

Helgerud, Michael B.↗