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At least 289 records · Page 16

All sources NASA NTRS DOE OSTI

NASA NTRS2012

Reducing Extra-Terrestrial Excavation Forces with Percussion

High launch costs and mission requirements drive the need for low mass excavators with mobility platforms, which in turn have little traction and excavation reaction capacity in low gravity environments. This presents the need for precursor and long term future missions with low mass robotic mining technology to perform In-Situ Resource Utilization (ISRU) tasks. This paper discusses a series of experiments that investigate the effectiveness of a percussive digging device to reduce excavation loads and thereby the mass of the excavator itself. The goal of percussive excavation is to fluidize dry regolith in front of the leading edge of the tool by mechanically separating the microscopic interlocking grains resulting in a reduced force needed to shear the soil. There are several variables involved with this technique; this experiment varied: Impact energy, frequency, and excavation speed and held constant: impact direction, depth of cut, angle of tool, and soil bulk density. The test apparatus consisted of an aluminum truss bridge with a central pivoting arm. Attached to the arm was a winch with a load cell in line that recorded the tension in the cable and therefore the excavation load. The arm could be adjusted for excavation depth which was recorded along with the arm angle relative to the bridge. A percussive mechanism and 30" wide pivoting bucket were attached at the end of the arm simulating a basic backhoe with a percussion direction tangent to the direction of . movement. Internally the mechanism used a set of die springs and barrel cam to produce the percussive blow. By changing the springs and the speed of the motor the impact energy and frequency of percussion could be varied independently. Impact energies from 11.2J to 30.5J and frequencies from 0 BPM to 700 BPM were investigated. A reduction in excavation force of as much as 51% was achieved in this experimental investigation. Smaller percussive digging implements, tested by others, have achieved a reduction of as much as 72%. This paper will examine the effects of impact energy, frequency, scaling and their effect on excavation forces in a dry granular material such as lunar regolith. The past several years have shown an increasing interest in mining space resources both for exploration and commercial enterprises. This work studied the benefits and risks of percussive excavation and prelimin~ry results indicate that this technique may become an enabling technology for extra-terrestrial excavation of regolith and ice.

Schuler, Jason↗

NASA NTRS2012

Reducing Extra-Terrestrial Excavation Forces with Percussion

Mueller, Robert↗

NASA NTRSDate not supplied

Spectral Properties of Dust on Asteroid (101955) Bennu with the OSIRIS-REx Visible and Infrared Spectrometer (OVIRS)

The Origins, Spectral Interpretation, Resource Identification, Security-Regolith Explorer (OSIRIS-REx) spacecraft successfully collected a sample of regolith from asteroid (101955) Bennu on October 20, 2020[1]. The Touch-and-Go (TAG) spacecraft maneuver used to collect the sample mobilized material, including very fine particles (dust),from up to ~1m in depth and ~10m in diameter from the point of contact with the asteroid [1,2].TAG created a dust plume that intercepted the spacecraft and accumulated on the instruments. As a result, all instruments show degradation in optical throughput, with the degree of degradation depending on their aperture size, orientation, and position on the spacecraft [1]. In this study, we analyzed OSIRIS-REx Visible and Infrared Spectrometer (OVIRS) from before and after TAG to assess the dust on the instrument with implications for Bennu’s dust composition and scattering properties, and future visible–near-infrared (VNIR)spectral observations with the OSIRIS-REx spacecraft. OVIRS is a point spectrometer that measures reflected light at VNIR wavelengths from 0.4 to 4.3 μm with a 4 mrad circular field of view(FOV) [3]. Previous observations with OVIRS revealed widespread hydrated minerals and carbon-bearing materials on Bennu [4,5]. A ~3 μm absorption feature is observed globally in OVIRS spectra, with a band position and depth that is consistent with Mg/Fe phyllosilicates and suggests a similar degree of aqueous alteration to that experienced by some carbonaceous chondrite meteorites[4,6]. A series of weak (<5%) VNIR spectral features, potentially associated with hydrated phyllosilicates and iron oxides, are also found in OVIRS spectra (Fig. 1), though not typically observed in meteorite spectra [7]. OSIRIS-REx Thermal Emission Spectrometer (OTES) spectra are consistent with a very thin accumulation (a few to ~ten microns) of fine particles (<~65–100 microns in size)across the surface of Bennu, and particularly on the roughest boulders, an interpretation that is supported by the dust plume seen during TAG [1,8]. An analysis of TAG contamination on the OTES optics revealed a 15% decrease in throughput, and OTES observations of space with and without that contamination allow a recreation of the thermal infrared spectrum [1]. The spectrum of the contamination lacks volume scattering features and exhibits a stronger Mg-OH absorption (~16.5 μm) than average Bennu, suggesting a Mg-rich phyllosilicate composition [1,6]. Here we present the first compositional analysis of Bennu dust at VNIR wavelengths by analyzing the contaminant on OVIRS.

H H Kaplan↗

DOE OSTI2024

An integrated transportation-power system model for a decarbonizing world

Rising demand for electricity from electric vehicles (EVs) will require new paradigms to guarantee reliable and low-cost electricity. This study couples an agent-based travel demand simulator and an electricity grid model to assess the economic costs of supplying power to meet EVs' added demand across the Chicago region. Results suggest that shifting from personal EVs to a fleet of shared, fully-automated all-electric vehicles (SAEVs) could lower per-mile emissions, congestion, and embodied vehicle and charging infrastructure emissions. Further, the results should compel policymakers to shift the cost of providing power onto commercial customers, like electric ride-hail fleets, through price-indexed electricity prices, which can shift charging to off-peak periods or away from resource-scarce hours.

Integrated modeling↗

NASA NTRS2013

Using Combustion Synthesis to Reinforce Berms and Other Regolith Structures

The Moonraker Excavator and other tools under development for use on the Moon, Mars, and asteroids will be employed to construct a number of civil engineering projects and to mine the soil. Mounds of loose soil will be subject to the local transport mechanisms plus artificial mechanisms such as blast effects from landers and erosion from surface vehicles. Some of these structures will require some permanence, with a minimum of maintenance and upkeep. Combustion Synthesis (CS) is a family of processes and techniques whereby chemistry is used to transform materials, often creating flame in a hard vacuum. CS can be used to stabilize civil engineering works such as berms, habitat shielding, ramps, pads, roadways, and the like. The method is to unroll thin sheets of CS fabric between layers of regolith and then fire the fabric, creating a continuous sheet of crusty material to be interposed among layers of loose regolith. The combination of low-energy processes, ISRU (in situ resource utilization) excavator, and CS fabrics, seems compelling as a general method for establishing structures of some permanence and utility, especially in the role of robotic missions as precursors to manned exploration and settlement. In robotic precursory missions, excavator/ mobility ensembles mine the Lunar surface, erect constructions of soil, and dispense sheets of CS fabrics that are covered with layers of soil, fired, and then again covered with layers of soil, iterating until the desired dimensions and forms are achieved. At the base of each berm, for example, is a shallow trench lined with CS fabric, fired and filled, mounded, and then covered and fired, iteratively to provide a footing against lateral shear. A larger trench is host to a habitat module, backfilled, covered with fabric, covered with soil, and fired. Covering the applied CS fabric with layers of soil before firing allows the resulting matrix to incorporate soil both above and below the fabric ply into the fused layer, developing a very irregular surface which, like sandpaper, can provide an anchor for loose soil. CS fabrics employ a coarse fiberglass weave that persists as reinforcement for the fired material. The fiberglass softens at a temperature that exceeds the combustion temperature by factors of two to three, and withstands the installation process. This type of structure should be more resistant to rocket blast effects from Lunar landers.

Rodriquez, Gary↗

NASA NTRS2018

Additive Construction with Mobile Emplacement: Multifaceted Planetary Construction Materials Development

The National Aeronautics and Space Administration's Additive Construction with Mobile Emplacement (ACME) project is developing construction materials with which infrastructure elements, including habitats, will be additively constructed for planetary surface missions. These materials must meet requirements such as the ability to be produced from available in-situ resources to eliminate the cost of launching materials from Earth, the ability to be emplaced via three dimensional building techniques, the ability to resist aging in extreme environments including radiation and micrometeorite bombardment, and the ability to provide the necessary structural integrity for a given building. This paper reviews the constraints placed on such planetary construction materials and details the work of the ACME team in characterizing materials that could one day construct planetary surface structures on Mars or the Moon. Material compositions, compressive strength, and requirements for additive construction on planetary surfaces are discussed. Due to the multifunctional requirements of the material, an optimization is necessary to balance between the site-specific regolith composition, emplacement via additive construction techniques, and characteristics of the final structure.

simulant↗

NASA NTRS1978

Environmental assessment of the proposed nonelectric application of geothermal resources at Desert Hot Springs, California

The paper presents an environmental analysis performed in evaluating various proposed geothermal demonstration projects at Desert Hot Springs. These are categorized in two ways: (1) indirect, or (2) direct uses. Among the former are greenhouses, industrial complexes, and car washes. The latter include aquaculture, a cascaded agribusiness system, and a mobile home park. Major categories of environmental impact covered are: (1) site, (2) construction of projects, and (3) the use of the geothermal source. Attention is also given to the disposal of the geothermal fluid after use. Finally, it is concluded that there are no major problems forseen for each project, and future objectives are discussed.

Rosenberg, L.↗

NASA NTRS1994

Channel characterisation for future Ka-band Mobile Satellite Systems and preliminary results

Mobile satellite systems (MSS) are presently designed or planned to operate, with the exception of OMNITRACKS, in the lower part of the frequency spectrum (UHF to S-bands). The decisions taken at the last World Administrative Radio Conference in 1992 to increase the allocated L- and S-bands for MSS services will only partly alleviate the problem of system capacity. In addition the use of L-and S-band frequencies generally requires large antenna apertures on board the satellite terminal side. The idea of exploiting the large spectrum resources available at higher frequencies (20-30 GHz) and the perspective of reducing user terminal size (and possibly price too) have spurred the interest of systems designers and planners. On the other hand, Ka-band frequencies suffer from increased slant path losses due to atmospheric attenuation phenomena. The European Space Agency (ESA) has recently embarked on a number of activities aimed at studying the effect of the typical mobile propagation impairments at Ka-band. This paper briefly summarizes ESA efforts in this field of research and presents preliminary experimental results.

Sforza, Mario↗

NASA NTRS1990

Satellite sound broadcast propagation studies and measurements

Satellite Sound Broadcasting is an attractive satellite application. Before regulatory decisions can be made in 1992, the propagation effects encountered have to be characterized. The Electrical Engineering Research Laboratory has nearly completed a system which will allow amplitude measurements to be made over 10 MHz bandwidths in the 800 to 1800 MHz frequency range. The system uses transmission from a transportable tower, and reception inside buildings or in the shadow of trees or utility poles. The goal is to derive propagation models for use by systems engineers who are about to design satellite broadcast systems. The advance of fiber-optics technology has helped to focus future development of satellite services into areas where satellites are uniquely competitive. One of these preferred satellite applications is the broadcasting of high-quality sound for stationary or mobile reception by listeners using low-cost, consumer-grade receivers. Before such services can be provided, however, the political hurdles of spectrum allocation have to be surmounted and the technical questions of standardization for world-wide compatibility have to be resolved. In order to arrive at an optimal system design, efficient in the use of our scarce spectral resources, affordable both to the broadcaster and the listener, and providing predictable performance, the propagation effects to which the service is subjected have to be characterized. Consequently, the objective of the research project is to make basic propagation measurements for direct Satellite Sound Broadcasting Service (SSBS). The data obtained should allow the development of propagation models to be used by communications engineers designing the operational systems. Such models shall describe the effects of shadowing and multipath propagation on SSBS receivers operating in a specified environment, such as inside commercial or residential buildings of various construction and also in the shadow of trees or utility poles as might be encountered by transporting or mobile listeners.

Vogel, Wolfhard J.↗

DOE OSTI2023

Metatranscriptomics sheds light on the links between the functional traits of fungal guilds and ecological processes in forest soil ecosystems

Soil fungi belonging to different functional guilds, such as saprotrophs, pathogens, and mycorrhizal symbionts, play key roles in forest ecosystems. To date, no study has compared the actual gene expression of these guilds in different forest soils. We used metatranscriptomics to study the competition for organic resources by these fungal groups in boreal, temperate, and Mediterranean forest soils. Using a dedicated mRNA annotation pipeline combined with the JGI MycoCosm database, we compared the transcripts of these three fungal guilds, targeting enzymes involved in C- and N mobilization from plant and microbial cell walls. Genes encoding enzymes involved in the degradation of plant cell walls were expressed at a higher level in saprotrophic fungi than in ectomycorrhizal and pathogenic fungi. However, ectomycorrhizal and saprotrophic fungi showed similarly high expression levels of genes encoding enzymes involved in fungal cell wall degradation. Transcripts for N-related transporters were more highly expressed in ectomycorrhizal fungi than in other groups. Here, we showed that ectomycorrhizal and saprotrophic fungi compete for N in soil organic matter, suggesting that their interactions could decelerate C cycling. Metatranscriptomics provides a unique tool to test controversial ecological hypotheses and to better understand the underlying ecological processes involved in soil functioning and carbon stabilization.

59 BASIC BIOLOGICAL SCIENCES↗

DOE OSTI2023

Massive Trajectory Data Based on Patterns of Life

Individual human location trajectory and check-in data have been the driving force for human mobility research in recent years. However, existing human mobility datasets are very limited in size and representativeness. For example, one of the largest and most commonly used datasets of individual human location trajectories, GeoLife, captures fewer than two hundred individuals. To help fill this gap, this Data and Resources paper leverages an existing data generator based on fine-grained simulation of individual human patterns of life to produce large-scale trajectory, check-in, and social network data. In this simulation, individual human agents commute between their home and work locations, visit restaurants to eat, and visit recreational sites to meet friends. We provide large datasets of months of simulated trajectories for two example regions in the United States: San Francisco and New Orleans. In addition to making the datasets available, we also provide instructions on how the simulation can be used to re-generate data, thus allowing researchers to generate the data locally without downloading prohibitively large files.

Amiri, Hossein↗

NASA NTRS1988

Holographic particle detection

The feasibility was studied of developing a novel particle track detector based on the detection of 1p-1s emission radiation from electron bubbles in liquid helium. The principles, design, construction, and initial testing of the detection system have been described in previous reports. The main obstacle encountered was the construction of the liquid-helium tight infrared windows. Despite numerous efforts in testing and redesigning the windows, the problem of window leakage at low temperature persisted. Due to limited time and resources, attention was switched to investigating the possibility of using room-temperature liquid as the detection medium. A possible mechanism was the detection of de-excitation radiation emitted from localized electrons in common liquids where electrons exhibit low mobilities, as suggested in the previous report. The purity of the liquid is critical in this method as the dissolved impurities (such as oxygen), even in trace amounts, will act as scavengers of electrons. Another mechanism is discussed whereby the formation of the superoxide ions by electron scavenging behavior of dissolved oxygen is exploited to detect the track of ionizing particles. An experiment to measure the ionization current produced in a liquid by a pulsed X-ray beam in order to study propertiies of the ions is also reported.

Bowen, Theodore↗

DOE OSTI2022

A shared-mobility-based framework for evacuation planning and operations under forecast uncertainty

To meet evacuation needs from carless populations who need personalized assistance to evacuate safely, in this article we propose a ridesharing-based evacuation program that recruits volunteer drivers before a disaster strikes, and then matches volunteer drivers with evacuees once demand is realized. Here we optimize resource planning and evacuation operations under uncertain spatiotemporal demand, and construct a two-stage stochastic mixed-integer program to ensure high demand fulfillment rates. We consider three formulations to improve the number of evacuees served, by minimizing an expected penalty cost, imposing a probabilistic constraint, and enforcing a constraint on the conditional value at risk of the total number of unserved evacuees, respectively. We discuss the benefits and disadvantages of the different risk measures used in the three formulations, given certain carless population sizes and the variety of evacuation modes available. We also develop a heuristic approach to provide quick, dynamic and conservative solutions. We demonstrate the performance of our approaches using five different networks of varying sizes based on regions of Charleston County, South Carolina, an area that experienced a mandatory evacuation order during Hurricane Florence, and utilize real demographic data and hourly traffic count data to estimate the demand distribution.

97 MATHEMATICS AND COMPUTING↗

NASA NTRS2020

A Systematic Review of Local to Regional Yield Forecasting Approaches and Frequently Used Data Resources

Forecasting crop yields, or providing an expectation of ex-ante harvest amounts, is highly relevant to the whole agricultural production chain. Farmers can adapt their management, traders or insurers their pricing schemes, suppliers their stocks, logistic companies their routes, national authorities their food balance sheets to guide import or export and, finally, international aid organizations can mobilize reliefs. Evidence has grown in the literature that such forecasts with a meaningful lead time are possible on various geographic scales and for a broad range of crops. Here, we present a systematic review of the methods applied in end-of-season yield forecasting and three frequently used data sources: weather data, satellite data and crop masks. Our literature database comprises 362 studies (2004–2019) which were evaluated regarding methods, crops, regions, data sources, lead time and performance. Moreover, we present 24 sources of real-time and predictive weather data, 21 sources of remote sensing data and 16 crop masks. Yield forecasting in our literature sample has been performed for 44 crops in 71 countries, also including many non-staple crops, but with an apparent bias in regions and crops. Forecasting performance depends on various factors, including crop, region, method, lead time to harvest and input diversity. Our systematic review supports a broader application of locally successful approaches at larger scales by providing a comprehensive, accessible compendium of necessary information for yield forecasting. We discuss improvement potentials with respect to methodological approaches and available data sources. We additionally suggest standardization procedures for future forecasting studies and encourage studying additional crops and geographic regions. Implications of forecasts for different target groups on different scales and the adaptation towards climate change are also discussed.

Seasonal crop yield forecasting↗

DOE OSTI2026

Community Resilience Through Rapid Restoration Leveraging Distributed Energy Resources (DERs) and Low-Cost Sensors

Equitable and automated bottoms-up power restoration following an extreme event will be demonstrated at a site in Puerto Rico. To do so, the team will develop enhanced grid situational awareness techniques integrating behind-the-meter (BTM) distributed energy resources (DER) discovery, impedance sweeping based outage boundary detection, and feasible restoration path identification algorithms. Resilience metric will be developed and incorporated along with situational awareness information in a distributed Model Predictive Control (MPC)-based restoration optimization algorithm to control and mobilize grid assets. These algorithms will be validated through power hardware-in-the-loop experiments and ultimately, a site demonstration to show that outage recovery time and total recovered load could be improved by >20% over the baseline.

24 POWER TRANSMISSION AND DISTRIBUTION↗

NASA NTRS1993

Low cost coherent demodulation for mobile satellite terminals

This paper describes some low cost approaches to coherent BPSK demodulation for mobile satellite receivers. The specific application is an Inmarsat-C Land Mobile Earth Station (LMES), but the techniques are applicable to any PSK demodulator. The techniques discussed include combined sampling and quadrature downconversion with a single A/D and novel DSP algorithms for carrier acquisition offering both superior performance and economy of DSP resources. The DSP algorithms run at 5.7 MIPS, and the entire DSP subsystem, built with commercially available parts, costs under $60 at quantity-10,000.

Dutta, Santanu↗

NASA NTRS2017

The Utility of a Small Pressurized Rover with Suit Ports for Lunar Exploration: A Geologist's Perspective

Rover trade study: As summarized recently, mission simulations at Black Point Lava Flow (Arizona) that included realistic extravehicular activity (EVA) tasking, accurate traverse timelines, and an in-loop science CAPCOM (or SciCOM) showed that a small pressurized rover (SPR) was a better mobility asset than an unpressurized rover (UPR). Traverses within the SPR were easier on crew than spending an entire day in a spacesuit, enhancing crew productivity at each station. The SPR, named Lunar Electric Rover (LER), and sometimes called the Space Exploration Vehicle (SEV), could also provide shelter during a suit malfunction, radiation event, or medical emergency that might occur on the Moon. Intravehicular activity (IVA) capabilities: From within the vehicle, crew could describe and photo-document distant features during drives between stations, as well as in the near-field, directly in front of the LER, providing an ability to begin EVA planning on approach to each outcrop prior to egress. The vehicle can rotate 360º without any lateral movement, providing views in all directions. It has high-visibility windows, a ForeCam, AftCam, port and starboard cameras, docking cameras, and a GigaPan camera. EVA capabilities: To reduce timeline, mass, and volumetric overhead, rapid egress and ingress were envisioned, replacing an airlock with lower cabin pressure than on the International Space Station and suit ports on the aft cabin wall [2]. When needed for closer inspection and sample collecting, crew could egress in about 10 minutes through suit ports. Crew use SuitCams for additional photo-documentation, transmit mobile observations verbally, and collect surface materials. Typical simulations involved 3 to 4 EVA stations/day and 2 to 3 hr/day of boots on the ground. This allowed crew to explore a far larger territory, with more complex geological and in situ resource utilization (ISRU) features, than would a single, longer-duration EVA at one location, while also minimizing crew time in a spacesuit. Additionally, the vehicle could be driven with crew locked into the suit ports. This approach could involve a driver in the cockpit with a suited crewmember in a suit port, or the vehicle could be driven from the aft deck with both crewmembers in their suit ports. This approach was used when distances between stops were short enough that vehicle ingress and egress were less efficient than remaining in the suits and driving. Utility of suit ports: The advantages of suit ports were clearly demonstrated in those field-based trade studies. To illustrate those advantages further, consider the consequences of a SPR without suit ports at the Apollo 17 landing site. At that site, the crew's second EVA was an approximately 18 km loop conducted in a UPR, called the Lunar Roving Vehicle (LRV), in 7 hr 36 min 56 s. The traverse was composed of 5 formal stations, plus 8 additional LRV stations where crew made brief scientific stops. In a scenario involving a SPR without suit ports, crew would go EVA through an airlock and probably be limited to a single EVA per day. In that case, crew could drive the SPR ~9 km from the landing site to station 2, go EVA, and complete station 2 tasks. However, to conduct station 3 tasks, the crew would then need to walk approximately 3 km to station 3, while ground control in Houston tele-robotically drives the LER to station 3. A walk of approximately 3 km is possible, as that is what the Apollo 14 crew did before LRVs were deployed, but it is a lengthy and potentially grueling EVA. Assuming crew completes station 3 tasks, they would likely need to re-enter the SPR, ending the day's EVA, and return to the landing site. They would not be able to walk the additional distances to stations 4 and 5 (the latter being about 6 km from station 3). Thus, crew in an SPR without suit ports would require two days to accomplish the same tasks Apollo 17 crew completed in a single day. If a future crew is involved in long duration traverses on the lunar surface, the deployment of a vehicle with suit ports would probably be a better solution.

Kring, David A.↗

NASA NTRSDate not supplied

Preliminary Steps in Developing Rapid Aero Modeling Technology

The Rapid Aero Modeling (RAM) approach is a method to efficiently and automatically obtain aerodynamic models during testing, significantly saving time and resources. Motivation for this technology results from demand for experimental efficiency and model fidelity that has increased with growing aircraft complexity and aerodynamic nonlinearities. These issues are typical in the responses presented by a class of vehicles categorized as Urban Air Mobility aircraft where many features from both airplane and rotorcraft are present. For UAM configurations, with typically many more factors than conventional aircraft, traditional test methods can lead to increased costs and missed interactions. RAM guides the test to obtain high-fidelity, statistically rigorous aircraft models, and the approach is applicable to computational, ground, or flight-test experiments. It combines concepts from Design of Experiment theory and Aircraft System Identification theory that allow the user the freedom to choose, in advance of the test, a specific level of fidelity typically, in terms of prediction error. RAM only collects data required to meet the user-specified fidelity and fidelity is only limited by the facility and test article capabilities. An initial wind tunnel test to support development of RAM was conducted to assess potential metrics, algorithms, and procedures. This paper presents results from initial tests for the development of RAM technology and highlights some of the unique features of RAM applied toa conventional configuration during a ground-based, static, wind-tunnel test.

Patrick C Murphy↗