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NASA NTRS2022

Kelvin-Helmholtz Vortices as an Interplay of Magnetosphere-Ionosphere Coupling

The solar wind-magnetosphere interaction drives diverse physical processes on the flanks of Earth’s magnetopause, and in turn these processes couple to the ionosphere. We investigate simultaneous multipoint in-situ spacecraft and ground-based measurements to determine the role of Kelvin-Helmholtz waves at the Earth’s magnetopause and the low-latitude boundary layer in the magnetosphere-ionosphere coupling process. Nonlinear Kelvin-Helmholtz waves develop into flow vortices that twist and/or shear flux tube magnetic fields, thereby generating localized field-aligned currents. Kelvin-Helmholtz vortices on the dusk (dawn) flanks of the magnetosphere generate clockwise (counter-clockwise) rotations and upward (downward) field-aligned currents inside the flux tubes, consistent with the region-1 field-aligned current. We present in-situ MMS and Cluster spacecraft observations of Kelvin-Helmholtz vortices at the magnetopause that map to the poleward edge of the auroral regions. The FAST spacecraft and the ground-based magnetometers from which spherical elementary currents (acting as a proxy for vertical currents) can be calculated observe corresponding field-aligned current signatures. This study demonstrates the role played by the Kelvin-Helmholtz waves in linking magnetopause boundary fluctuations to ionospheric phenomena.

K-J Hwang↗

NASA NTRS2024

Mapping Recent Coastal Shoreline Changes in Southwestern Alaska Using Landsat 8 Satellite Imagery

Coastal communities in Alaska are frequently subjected to storm surges that erode shorelines and riverbanks, which increases flood risks around critical village infrastructure. Coastal erosion in western Alaska may be occurring currently at rates as high as 15 m per year, but the region has not been mapped in enough detail to accurately assess recent shoreline and inland riverbank erosion rates. To update the mapping of changes in all of SWAlaska’s coastal margins, Landsat 8 satellite imagery was analyzed to detect trends in the normalized difference water index collected from 2013 to 2023. The normalized difference water index values range from -1 to 1, with negative values indicating majority land that includes soil and live vegetation cover and positive values indicating majority water coverage. Results showed marked coastal shoreline erosion at Chagvan Bay, Hagemeister Island, and Nanvak Bay over the past decade. Additional locations of recent bank erosion were detected on the Kuskokwim River, from its upriver mouth past the city of Bethel. Riverbank erosion was also detected in northern Nushagak Bay, and extensive surface-wetting trends around wetlands and riverbanks were detected near the village of Togiak. Moreover, many villages on the west coast of Alaska and in the Kuskokwim River Delta have recently documented climate change case studies highlighting bank erosion, indicating that a variety of related ecological disturbances are ongoing across the region.

Imagery↗

NASA NTRS2003

High-Energy Two-Stage Pulsed Plasma Thruster

A high-energy (28 kJ per pulse) two-stage pulsed plasma thruster (MSFC PPT-1) has been constructed and tested. The motivation of this project is to develop a high power (approximately 500 kW), high specific impulse (approximately 10000 s), highly efficient (greater than 50%) thruster for use as primary propulsion in a high power nuclear electric propulsion system. PPT-1 was designed to overcome four negative characteristics which have detracted from the utility of pulsed plasma thrusters: poor electrical efficiency, poor propellant utilization efficiency, electrode erosion, and reliability issues associated with the use of high speed gas valves and high current switches. Traditional PPTs have been plagued with poor efficiency because they have not been operated in a plasma regime that fully exploits the potential benefits of pulsed plasma acceleration by electromagnetic forces. PPTs have generally been used to accelerate low-density plasmas with long current pulses. Operation of thrusters in this plasma regime allows for the development of certain undesirable particle-kinetic effects, such as Hall effect-induced current sheet canting. PPT-1 was designed to propel a highly collisional, dense plasma that has more fluid-like properties and, hence, is more effectively pushed by a magnetic field. The high-density plasma loading into the second stage of the accelerator is achieved through the use of a dense plasma injector (first stage). The injector produces a thermal plasma, derived from a molten lithium propellant feed system, which is subsequently accelerated by the second stage using mega-amp level currents, which eject the plasma at a speed on the order of 100 kilometers per second. Traditional PPTs also suffer from dynamic efficiency losses associated with snowplow loading of distributed neutral propellant. The twostage scheme used in PPT-I allows the propellant to be loaded in a manner which more closely approximates the optimal slug loading. Lithium propellant was chosen to test whether or not the reduced electrode erosion found in the Lithium Lorentz Force Accelerator (LiLFA) could also be realized in a pulsed plasma thruster. The use of the molten lithium dense plasma injector also eliminates the need for a gas valve and electrical switch; the injector design fulfills both roles, and uses no moving parts to provide, in principle, a highly reliable propellant feed and electrical switching system. Experimental results reported in this paper include: second-stage current traces, high-speed photographic and holographic imaging of the thruster exit plume, and internal mapping of the discharge chamber magnetic field from B-dot probe data. The magnetic field data is used to create a two-dimensional description of the evolution of the current sheet inside the thruster.

Markusic, Tom↗

NASA NTRS2012

Analysis of Temperature Maps of Selected Dawn Data Over the Surface of Vesta

The thermal behavior of areas of unusual albedo at the surface of Vesta can be related to physical properties that may provide some information about the origin of those materials. Dawn s Visible and Infrared Mapping Spectrometer (VIR) [1] hyperspectral cubes can be used to retrieve surface temperatures. Due to instrumental constraints, high accuracy is obtained only if temperatures are greater than 180 K. Bright and dark surface materials on Vesta are currently investigated by the Dawn team [e.g., 2 and 3 respectively]. Here we present temperature maps of several local-scale features that were observed by Dawn under different illumination conditions and different local solar times.

Tosi, F.↗

NASA NTRS2010

Development and Evaluation of a Cloud-Gap-Filled MODIS Daily Snow-Cover Product

The utility of the Moderate Resolution Imaging Spectroradiometer (MODIS) snow-cover products is limited by cloud cover which causes gaps in the daily snow-cover map products. We describe a cloud-gap-filled (CGF) daily snowcover map using a simple algorithm to track cloud persistence, to account for the uncertainty created by the age of the snow observation. Developed from the 0.050 resolution climate-modeling grid daily snow-cover product, MOD10C1, each grid cell of the CGF map provides a cloud-persistence count (CPC) that tells whether the current or a prior day was used to make the snow decision. Percentage of grid cells "observable" is shown to increase dramatically when prior days are considered. The effectiveness of the CGF product is evaluated by conducting a suite of data assimilation experiments using the community Noah land surface model in the NASA Land Information System (LIS) framework. The Noah model forecasts of snow conditions, such as snow-water equivalent (SWE), are updated based on the observations of snow cover which are obtained either from the MOD1 OC1 standard product or the new CGF product. The assimilation integrations using the CGF maps provide domain averaged bias improvement of -11 %, whereas such improvement using the standard MOD1 OC1 maps is -3%. These improvements suggest that the Noah model underestimates SWE and snow depth fields, and that the assimilation integrations contribute to correcting this systematic error. We conclude that the gap-filling strategy is an effective approach for increasing cloud-free observations of snow cover.

Hall, Dorothy K.↗

NASA NTRS1972

Study of the marine environment of the northern Gulf of California

The author has identified the following significant results. Preliminary analysis of the first three months of ERTS-1 imagery have revealed that the MSS images have particular utility for study of turbidity patterns, current phenomena, and bathymetry throughout the test area. Early indications are that well defined spatial distributions of turbidity exist in the northern Gulf of California, and that for any one point in time, these distributions vary with depth. From a single set of images, as many as 3 turbidity maps may be generated, each indicating a vertical spatial relationship of the turbidity masses. The spatial distribution of turbidity masses depend partially upon the coincident currents. In the band of deepest penetration, a map can be gathered which roughly corresponds to the bathymetry of the area. The extreme tides in the northern Gulf of California result in vast areas which can be classified as intertidal mud flats. Information on the amount of exposure at the varying tidal states is important in analysis of these mud flat areas as nursery ground for Mexican commercial fisheries.

Hendrickson, J. R.↗

NASA NTRS1997

The Development of an Electronic Aircraft Taxi Navigation Display

This paper describes the development of an electronic aircraft taxi navigation display as part of NASA's Terminal Area Productivity (TAP) Program. The impetus for the development of this specific display, and the TAP program as a whole, is the current bottleneck in surface operations experienced during low-visibility operations. Simply stated, while modern aircraft are equipped to fly and land in low-visibility conditions, they lack the related technology required to allow them to efficiently and safely navigation from the runway to the gate. Pilots under such conditions consequently taxi slower, sometimes get lost and have to stop, and occasionally collide with other aircraft. Based on a review of available display and navigation sensor technologies, and a one-year information requirements study conducted aboard several commercial aircraft flights, it was determined that an electronic aircraft taxi navigation display was the most viable option for improving the efficiency of low-visibility taxi operations. Based on flight deck observations and pilot interviews, previous map display research, other taxi map display efforts, and part-task taxi map research, an advanced taxi navigation display has been developed and is currently being tested. The taxi navigation display is presented as a head-down cockpit display and includes a track-up perspective airport surface view, taxiway, gate and runway labels, ownship position, traffic icons and collision annunciation, graphical route guidance, heading indicator, rotating compass, RVR wedge, stop bars, zoom control, and datalink message window. The development and support for each of the features will be discussed in detail. Additional information is contained in the original extended abstract.

Andre, Anthony D.↗

NASA NTRS1977

The N.A.S.A. earth and ocean dynamics programme

Practical applications of NASA space systems, science, and technology to the study of oceans and solid earth are discussed. Goals involving earth dynamics include earthquake hazard assessment and alleviation, and global surveying and mapping, while goals involving ocean dynamics include the determination of ocean currents and circulation, and the monitoring of ocean surface conditions. Satellites used to obtain data are described, and projects such as the study of open ocean tides and earth motion determination are reviewed, with consideration given to the techniques (e.g., laser ranging, satellite-to-satellite track) used in these studies. Several physical phenomena, the extent to which they presently can be measured, and possible future requirements for more accurate measurements are examined.

Vonbun, F. O.↗

NASA NTRS1982

Precipitable water: Its linear retrieval using leaps and bounds procedure and its global distribution from SEASAT SMMR data

Eight subsets using two to five frequencies of the SEASAT scanning multichannel microwave radiometer are examined to determine their potential in the retrieval of atmospheric water vapor content. Analysis indicates that the information concerning the 18 and 21 GHz channels are optimum for water vapor retrieval. A comparison with radiosonde observations gave an rms accuracy of approximately 0.40 g sq cm. The rms accuracy of precipitable water using different subsets was within 10 percent. Global maps of precipitable water over oceans using two and five channel retrieval (average of two and five channel retrieval) are given. Study of these maps reveals the possibility of global moisture distribution associated with oceanic currents and large scale general circulation in the atmosphere. A stable feature of the large scale circulation is noticed. The precipitable water is maximum over the Bay of Bengal and in the North Pacific over the Kuroshio current and shows a general latitudinal pattern.

Pandey, P. C.↗

NASA NTRS1991

The real-time control of planetary rovers through behavior modification

It is not yet clear of what type, and how much, intelligence is needed for a planetary rover to function semi-autonomously on a planetary surface. Current designs assume an advanced AI system that maintains a detailed map of its journeys and the surroundings, and that carefully calculates and tests every move in advance. To achieve these abilities, and because of the limitations of space-qualified electronics, the supporting rover is quite sizable, massing a large fraction of a ton, and requiring technology advances in everything from power to ground operations. An alternative approach is to use a behavior driven control scheme. Recent research has shown that many complex tasks may be achieved by programming a robot with a set of behaviors and activation or deactivating a subset of those behaviors as required by the specific situation in which the robot finds itself. Behavior control requires much less computation than is required by tradition AI planning techniques. The reduced computation requirements allows the entire rover to be scaled down as appropriate (only down-link communications and payload do not scale under these circumstances). The missions that can be handled by the real-time control and operation of a set of small, semi-autonomous, interacting, behavior-controlled planetary rovers are discussed.

Miller, David P.↗

NASA NTRS1993

Mapping and energization in the magnetotail. II - Particle acceleration

Mapping with the Tsyganenko (1989) or T89 magnetosphere model has been examined previously. In the present work, an attempt is made to evaluate quantitatively what the selection of T89 implies for steady-state particle energization. The Heppner and Maynard (1987) or HM87 electric field model is mapped from the ionosphere to the equatorial plane, and the electric currents associated with T89 are evaluated. Consideration is also given to the nature of the acceleration that occurs when cross-tail current is suddenly diverted to the ionosphere.

Kaufmann, Richard L.↗

NASA NTRS1993

The effect of scene content on speed, time, and distance perception

Helicopter flights performed at low-levels place high demands on pilots; they must simultaneously control the vehicle, avoid obstacles, and navigate. Therefore, pilots must correlate cues viewed in the external scene with information on map in order to maintain their geographical orientation. This is a particularly difficult task when helicopter pilots fly through visually unfamiliar terrain without highly detailed maps. As a result, pilots must often use estimates of elapsed time, distance traveled, and/or average speed in order to maintain a flight path indicated on a map during flight segments when these cues are absent. Therefore, the current study is concerned with the perception of speed, time, and distance, which we assume underlies the ability to orient oneself during these types of flight segments.

Awe, Cynthia A.↗

NASA NTRS2002

Software for Viewing Landsat Mosaic Images

A Windows-based computer program has been written to enable novice users (especially educators and students) to view images of large areas of the Earth (e.g., the continental United States) generated from image data acquired in the Landsat observations performed circa the year 1990. The large-area images are constructed as mosaics from the original Landsat images, which were acquired in several wavelength bands and each of which spans an area (in effect, one tile of a mosaic) of approx. 5 in latitude by approx. 6 deg in longitude. Whereas the original Landsat data are registered on a universal transverse Mercator (UTM) grid, the program converts the UTM coordinates of a mouse pointer in the image to latitude and longitude, which are continuously updated and displayed as the pointer is moved. The mosaic image currently on display can be exported as a Windows bit-map file. Other images (e.g., of state boundaries or interstate highways) can be overlaid on Landsat mosaics. The program interacts with the user via standard toolbar, keyboard, and mouse user interfaces. The program is supplied on a compact disk along with tutorial and educational information.

Source record↗

NASA NTRS2002

Software for Viewing Landsat Mosaic Images

A Windows-based computer program has been written to enable novice users (especially educators and students) to view images of large areas of the Earth (e.g., the continental United States) generated from image data acquired in the Landsat observations performed circa the year 1990. The large-area images are constructed as mosaics from the original Landsat images, which were acquired in several wavelength bands and each of which spans an area (in effect, one tile of a mosaic) of 5 in latitude by approximately equal to 6 degrees in longitude. Whereas the original Landsat data are registered on a universal transverse Mercator (UTM) grid, the program converts the UTM coordinates of a mouse pointer in the image to latitude and longitude, which are continuously updated and displayed as the pointer is moved. The mosaic image currently on display can be exported as a Windows bit-map file. Other images (e.g., of state boundaries or interstate highways) can be overlaid on Landsat mosaics. The program interacts with the user via standard toolbar, keyboard, and mouse user interfaces. The program is supplied on a compact disk along with tutorial and educational information.

Watts, Jack↗

NASA NTRS2013

High Resolution Surface Science at Mars

The proposed mission would place a 2.4 m telescope in orbit around Mars with two focal plane instruments to obtain the highest resolution images and spectral maps of the surface to date (3-10x better than current). This investigation would make major contributions to all of the Mars Program Goals: life, climate, geology and preparation for human presence.

imaging↗

NASA NTRS2017

OCT Expanded Clinical Data Analysis

Vision changes identified in long duration space fliers has led to a more comprehensive clinical monitoring protocol. Optical Coherence Tomography (OCT) was recently implemented on board the International Space Station in 2013. NASA is collaborating with Heidelberg Engineering to expand our current OCT data analysis capability by implementing a volumetric approach. Volumetric maps will be created by combining the circle scan, the disc block scan, and the radial scan. This assessment may provide additional information about the optic nerve and further characterize changes related microgravity exposure. We will discuss challenges with collection and analysis of OCT data, present the results of this reanalysis and outline the potential benefits and limitations of the additional data.

Van Baalen, Mary↗

NASA NTRS2017

Coping with Higher Sea Levels and Increased Coastal Flooding in New York City

The 837 km New York City shoreline is lined by significant economic assets and dense population vulnerable to sea level rise and coastal flooding. After Hurricane Sandy in 2012, New York City developed a comprehensive plan to mitigate future climate risks, drawing upon the scientific expertise of the New York City Panel on Climate Change (NPCC), a special advisory group comprised of university and private-sector experts. This paper highlights current NPCC findings regarding sea level rise and coastal flooding, with some of the City's ongoing and planned responses. Twentieth century sea level rise in New York City (2.8 cm/decade) exceeded the global average (1.7 cm/decade), underscoring the enhanced regional risk to coastal hazards. NPCC (2015) projects future sea level rise at the Battery of 28 - 53 cm by the 2050s and 46 - 99 cm by the 2080s, relative to 2000 - 2004 (mid-range, 25th - 75th percentile). High-end SLR estimates (90th percentile) reach 76 cm by the 2050s, and 1.9 m by 2100. Combining these projections with updated FEMA flood return period curves, assuming static flood dynamics and storm behavior, flood heights for the 100-year storm (excluding waves) attain 3.9-4.5 m (mid-range), relative to the NAVD88 tidal datum, and 4.9 m (high end) by the 2080s, up from 3.4 m in the 2000s. Flood heights with a 1% annual chance of occurrence in the 2000s increase to 2.0 - 5.4% (mid-range) and 12.7% per year (high-end), by the 2080s. Guided by NPCC (2013, 2015) findings, New York City has embarked on a suite of initiatives to strengthen coastal defenses, employing various approaches tailored to specific neighborhood needs. NPCC continues its collaboration with the city to investigate vulnerability to extreme climate events, including heat waves, inland floods and coastal storms. Current research entails higher-resolution neighborhood-level coastal flood mapping, changes in storm characteristics, surge height interactions with sea level rise, and stronger engagement with stakeholders and community-based organizations.

Coastal flooding↗

NASA NTRSDate not supplied

Increasing Cognitive Ability/Reserve Using Software – Pilot (ICARUS-Pilot)

BACKGROUND This research study was competitively awarded under the 2022 JSC Innovation Charge Account (ICA) program administered by NASA Johnson Space Center’s Joint Technology Working Group. Study period of performance was May through September 2022, with a maximum allowed procurement budget of $10K. The study sought to quantify and assess the potential benefit of using commercial-off-the-shelf (COTS) cognitive training software to improve cognitive performance in an astronaut-like terrestrial population. METHODS Five volunteer research participants were recruited from the JSC employee population to mimic certain demographic characteristics of the NASA astronaut population (age, education/discipline). Participant cognitive performance was assessed before and after executing eighteen sessions of remote cognitive training executed nominally three times per week using six exercises within an adaptive app-based COTS software package (BrainHQ, Posit Science) on study-provided tablets. Pre- and post-training cognitive performance was measured using internal assessments in BrainHQ as well as Cognition Test Battery (CTB) version ISS B01 v3 (3.0.9-201710021500), an independent software test developed specifically for NASA and used currently in research studies on astronauts. BrainHQ exercises were posited to map well or partially to several CTB sub-tests. Participants provided feedback on their study experience formally via semi-structured interview at the conclusion of testing and informally throughout the study if they encountered issues. RESULTS The enrolled ICARUS-Pilot study participants generally matched Artemis crew demographic characteristics. Four of five participants have completed study training and assessment activities as of the writing of this abstract. These test participants complied well with desired training session frequency and duration yielding an average cumulative active training duration of 15 hours over an average of 45 days; participants showed 78% average improvement in metric performance for the six trained exercises, with an associated overall 33%ile ranking increase against performance of the entire BrainHQ subscribing population for internal pre/post assessment, agreeing with post-study survey self-reported performance increases. CTB overall feedback scoring, not corrected for learning effects, showed an average of 19% performance improvement across its 10 performance measures over the training period for the completed participants. Detailed analyses will be conducted once participant data collection for the study is complete and the resulting dataset is fully populated. DISCUSSION These preliminary results provide a positive trend for the effectiveness of the training approach, but further analysis will be needed to establish significance, investigate far transfer, and suggest the needed participant pool size for subsequent efforts to achieve statistically significant outcomes given similar results. The pilot study has already been helpful by allowing the study team to learn a great deal about the capabilities and limitations of the COTS software package that will be reflected in future proposals along with revised timelines for study execution and test participant management. From participant feedback, one common thread regarding the COTS training was that it felt overly repetitive – future proposals should reassess overall training duration, available levels for each trained exercise, and the behavior of the BrainHQ internal scheduler in determining which exercises should be trained and for how long. If the final analysis of this feasibility study ultimately supports it, the study team will recommend further investigation to fully evaluate this potential countermeasure and optimize its implementation. Future proposals would cite this feasibility study’s outcome and would seek to refine the training protocol and obtain statistically significant results for cognitive performance increases as well as retention data.

cognitive training↗