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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 415 records · Page 23
All sourcesNASA NTRSDOE OSTI
NASA NTRS2019

Towards Articulated Mobility and Efficient Docking for the DuAxel Tethered Robot System

Sites of increasing interest for planetary science,such as craters, cold traps, and vents lie in terrains that are inaccessible to state-of-the-art rovers. The Jet Propulsion Laboratory, in collaboration with Caltech, is actively developing a tethered mobile robot, Axel, for traversing and exploring extremely steep terrain, such as Recurring Slope Lineae on Mars and vertical pits on the Moon. However, on Mars, where landing-site uncertainty is high due to the presence of an atmosphere, Axel may need to traverse several kilometers from its lander untethered due to a finite tether carrying capacity (⇠300m). This paper proposes a novel design for a hybrid mobility system that allows a pair of Axel rovers to dock, lock, and drive long distances as a four-wheeled, articulated steering vehicle. The design improves upon prior efforts to achieve DuAxel mobility by leveraging two actuated docking mechanisms attached on opposite ends of a central module to enable ‘sit/stand’ functionality; the prior DuAxel system was limited to skid steering, which was inefficient due to Axel’s grouser-style, high-friction wheels. In the proposed system, the ‘sit’ configuration is achieved by aligning each dock parallel to the surface, allowing one Axel to detach and explore while the other remains docked and serves as a backup. While ‘sitting’, the central module rests on the ground and is outfitted with shovel-style wedges for passive anchoring to sandy terrain (an optional drill can be integrated for anchoring to rock). In order to ‘stand’, the exploring Axel reattaches, locks, and both docks are rotated until Axel’s tether caster arm is upright and the central module is lifted off the ground. Once upright, each Axel rotates about a pivot point for articulated, all-wheel steering, which is accomplished by applying differential wheel torques. The main contributions of this paper are i) a detailed systems design of the docking mechanism and central module, ii) kinematic modeling of articulated mobility and ‘sit/stand’ docking functionality, and iii) initial testing in a relevant environment to characterize the mobility of the proposed system.

Nesnas, Issa↗
NASA NTRS2018

A Novel Sensing Tether for Rovers

Luna has extended the length of its fiber optic shape sensing technology out to a continuous, high-fidelity measurement of a 100-meter sensor, creating a novel concept for a self-monitoring tether for robotic exploration. This tether is capable of measuring its own tension, curvature, and full 3-D shape along its entire length as it is deployed by a robotic rover. Using Optical Frequency Domain Reflectometry (OFDR) and the Rayleigh scatter signature to sense the state of a customized multicore optical fiber, the new technology is lightweight, compact, and immune to electromagnetic interference. Results are presented from tests with a 50-meter tether on the Axel Rover at JPL’s Mars Yard testing ground.

Kominsky, Daniel↗
DOE OSTI2026

Tethered Balloon System (TBS) Instrument Handbook

The Tethered Balloon System (TBS) is an unmanned aerial system composed of a helium-filled balloon, tether, winch, and sensors. Individual components of the system may change with each flight based on the desired measurements, atmospheric conditions, and flight strategy. The TBS operates within the U.S. Department of Energy (DOE)’s R-2204 Restricted Airspace, which encompasses a two-nautical-mile radius centered on Oliktok Point, Alaska that is segmented by altitude into R-2204 Low (0-1,499’ MSL or 0-457 m MSL) and R-2204 High (1,500-6,999’ MSL or 457-2133 m MSL). The TBS may operate outside of R-2204 if allowed to do so under a Certificate of Authorization from the Federal Aviation Administration.

42 ENGINEERING↗
NASA NTRS2016

Tethered Lunar Subsatellites for Multipoint and Low Altitude Measurements

The difficulty in making global measurements in orbit close to planetary bodies (and in particular the Moon) seriously constrains our ability to collect crucial, high-resolution data. We describe a unique and groundbreaking approach using tethered subsatellites to make measurements arbitrarily close to planetary surfaces, particularly those with no atmosphere, and to determine altitude profiles of geophysical parameters. The approach is feasible with current technology, and the subsatellite could be as small as a CubeSat. The initial results of a feasibility study and mission design for a tethered lunar CubeSat indicate that it is achievable.

Airless bodies↗
DOE OSTI2022

Tethering Effects in Oligomer-Based Metal–Organic Frameworks

Metal–organic frameworks (MOFs) can be con- structed using conventional molecular linkers or polymeric linkers (polyMOFs), but the relationship and relative properties of these related materials remain understudied. As an intermediate between these two extremes, a library of oligomeric ligand precursors (dimers, trimers) was used to prepare a series of oligomeric-linker MOFs (oligoMOFs) based on the prototypical IRMOF-1 system. IRMOF-1 was found to be remarkably tolerant to a wide variety of oligomeric linkers, the use of which greatly enhanced the MOF yield and prevented framework interpenetration. Tether length-dependent ordering of ligand and metal cluster orientations was also observed in these oligoMOFs. Improved low-humidity stability was found in oligoIRMOF-1 samples, with surface area preservation varying as a function of tether length and a complete suppression of crystalline hydrolysis products for all oligoIRMOF-1 materials. Furthermore, these findings pave the way toward a better understanding of the structure–function relationships between monomeric, oligomeric, and polymeric MOFs and highlight an underutilized strategy for tuning MOF properties.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2022

Effect of Tethering Anions in Block Copolymer Electrolytes via Molecular Dynamics Simulations

Ion-containing block copolymers (BCPs) are promising solid-state electrolytes as they can combine ion conduction and mechanical robustness via multiple microphases. However, salt-doped BCPs can have low ion conduction and transference number. One strategy to increase transference number is to tether anions to the polymer backbone (creating a single-ion conductor), though this may impact cation mobility. Leveraging coarse-grained molecular dynamics simulations, we compare the effects of ion concentration and polymer dielectric constant on BCPs with and without bonding anions to the chain (without changing any other chemical properties). We find that single-ion BCPs have higher cation conductivity than analogous salt-doped BCPs, especially at moderate ion concentrations. Furthermore, we also compare several structural features of these systems; notably, tethering anions causes the ions to spread more evenly throughout the conducting phase, which is related to improved cation conduction.

25 ENERGY STORAGE↗
DOE OSTI2026

Toward Rapid Actinium-225 Purification via Membrane Adsorbers with Covalently Tethered Diglycolamide Ligands

Extractive diglycolamide (DGA) resins are used in several state-of-the-art techniques for purifying 225 Ac, a promising radiometal for targeted alpha therapy. Unfortunately, separation processes that rely on resins are often limited to slow flow rates, high elution volumes, and long processing times. Membrane adsorbers functionalized with DGA ligands are an alternative separation material that may overcome these challenges. This work presents (1) the synthesis of an aminated tetrahexyldiglycolamide ligand, (2) the covalent tethering of the ligand to electrospun poly(vinylbenzyl chloride) fiber mats, and (3) the adsorption and desorption of La(III) and 225 Ac. Chemical and physical characterization supports the covalent tethering of the ligand to the fiber mat, as well as the preservation of the fiber surface area and porosity after functionalization. Equilibrium adsorption experiments were performed with stable La(III) and radioactive 225 Ac. Trends in affinity are consistent between commercial resins and the synthesized membrane adsorbers; however, the Langmuir constants and the maximum binding capacity of the membrane adsorbers were generally lower than the resins. Despite these differences, the modeled selectivity for an equimolar solution of La(III)/ 225 Ac in 10 M nitric acid is 57. Furthermore, 225 Ac is rapidly desorbed from the fibers in 10 M nitric acid (<20 min). The La(III)/ 225 Ac selectivity and rapid 225 Ac desorption indicate this class of materials is promising for rapid radioanalytical separations.

07 ISOTOPE AND RADIATION SOURCES↗
DOE OSTI2022

Three-dimensional structure-guided evolution of a ribosome with tethered subunits

We report RNA-based macromolecular machines, such as the ribosome, have functional parts reliant on structural interactions spanning sequence-distant regions. These features limit evolutionary exploration of mutant libraries and confound three-dimensional structure-guided design. To address these challenges, we describe Evolink (evolution and linkage), a method that enables high-throughput evolution of sequence-distant regions in large macromolecular machines, and library design guided by computational RNA modeling to enable exploration of structurally stable designs. Using Evolink, we evolved a tethered ribosome with a 58% increased activity in orthogonal protein translation and a 97% improvement in doubling times in SQ171 cells compared to a previously developed tethered ribosome, and reveal new permissible sequences in a pair of ribosomal helices with previously explored biological function. The Evolink approach may enable enhanced engineering of macromolecular machines for new and improved functions for synthetic biology.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2021

Arabidopsis myosin XIK interacts with the exocyst complex to facilitate vesicle tethering during exocytosis

Myosin motors are essential players in secretory vesicle trafficking and exocytosis in yeast and mammalian cells; however, similar roles in plants remain a matter for debate, at least for diffusely growing cells. Here, we demonstrate that Arabidopsis (Arabidopsis thaliana) myosin XIK, via its globular tail domain (GTD), participates in the vesicle tethering step of exocytosis through direct interactions with the exocyst complex. Specifically, myosin XIK GTD bound directly to several exocyst subunits in vitro and functional fluorescently tagged XIK colocalized with multiple exocyst subunits at plasma membrane (PM)-associated stationary foci. Moreover, genetic and pharmacological inhibition of myosin XI activity reduced the rate of appearance and lifetime of stationary exocyst complexes at the PM. By tracking single exocytosis events of cellulose synthase (CESA) complexes with high spatiotemporal resolution imaging and pair-wise colocalization of myosin XIK, exocyst subunits, and CESA6, we demonstrated that XIK associates with secretory vesicles earlier than exocyst and is required for the efficient localization and normal dynamic behavior of exocyst complex at the PM tethering site. This study reveals an important functional role for myosin XI in secretion and provides insights about the dynamic regulation of exocytosis in plants.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2020

Tethered Balloon Systems

Among ARM’s aerial platforms are tethered balloon systems (TBS), which consist of a helium-filled balloon, tether, winch, and sensors. TBS provide a safe way to collect data inside clouds, including mixed-phase clouds, where icing is a concern for airborne platforms. These systems are also flown above and below clouds to gather data related to wind, turbulence, thermodynamic state, aerosols, and the cloud-top environment.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2022

Strategies for Controlling the Spatial Orientation of Single Molecules Tethered on DNA Origami Templates Physisorbed on Glass Substrates: Intercalation and Stretching

Nanoarchitectural control of matter is crucial for next-generation technologies. DNA origami templates are harnessed to accurately position single molecules; however, direct single molecule evidence is lacking regarding how well DNA origami can control the orientation of such molecules in three-dimensional space, as well as the factors affecting control. Here, we present two strategies for controlling the polar (θ) and in-plane azimuthal (Φ) angular orientations of cyanine Cy5 single molecules tethered on rationally-designed DNA origami templates that are physically adsorbed (physisorbed) on glass substrates. By using dipolar imaging to evaluate Cy5's orientation and super-resolution microscopy, the absolute spatial orientation of Cy5 is calculated relative to the DNA template. The sequence-dependent partial intercalation of Cy5 is discovered and supported theoretically using density functional theory and molecular dynamics simulations, and it is harnessed as our first strategy to achieve θ control for a full revolution with dispersion as small as ±4.5°. In our second strategy, Φ control is achieved by mechanically stretching the Cy5 from its two tethers, being the dispersion ±10.3° for full stretching. These results can in principle be applied to any single molecule, expanding in this way the capabilities of DNA as a functional templating material for single-molecule orientation control. The experimental and modeling insights provided herein will help engineer similar self-assembling molecular systems based on polymers, such as RNA and proteins.

77 NANOSCIENCE AND NANOTECHNOLOGY↗
DOE OSTI2022

Calcium Sulfate and Calcium Carbonate Scaling of Thin-Film Composite Polyamide Reverse Osmosis Membranes with Surface-Tethered Polyacrylic Acid Chains

The gypsum and calcite scaling propensities of the thin-film composite polyamide (PA-TFC) reverse osmosis (RO) membrane, modified with a tethered surface layer of polyacrylic acid (PAA) chains, was evaluated and compared to the scaling of selected commercial RO membranes. The tethered PAA layer was synthesized onto a commercial polyamide membrane (i.e., base-PA) via atmospheric pressure plasma-induced graft polymerization (APPIGP). The PAA nano-structured (SNS) base-PA membrane (SNS-PAA-PA) was scaled to a lesser degree, as quantified by a lower permeate flux decline and surface imaging, relative to the tested commercial membranes (Dow SW30, Toray SWRO, and BWRO). The cleaning of gypsum-scaled membranes with D.I. water flushing achieved 100% water permeability recovery for both the SNS-PAA-PA and Dow SW30 membranes, relative to 92–98% permeability restoration for the Toray membranes. The calcium carbonate scaling of SNS-PAA-PA membranes was also lower relative to the commercial membranes, but permeability recovery after D.I. water cleaning was somewhat lower (94%) but consistent with the level of surface scale coverage. In contrast, the calcite and gypsum-scaled membrane areas of the commercial membranes post-cleaning were significantly higher than for the SNS-PAA-PA membrane but with 100% permeability recovery, suggesting the potential for membrane damage when mineral scaling is severe.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2022

Use of a Compliant Tether to Decouple Observation Buoy Motion for Auxiliary Wave Power

With the growth of the Blue Economy, the volume of data collection within the ocean environment has been rapidly increasing. Larger numbers of oceanographic, meteorological, and floating Light Detection And Ranging (LiDAR) buoys have been collecting high fidelity measurements while pushing against power budget limits. Power limitations lead to infrequent transmission of reduced data sets or recording data to local storage that must be physically collected when the buoy is serviced. Triton Systems, Inc. and its partners are developing a retrofittable wave energy converter (WEC) to provide auxiliary power to these observation buoys to increase mission duration and power budget, improve reliability, and reduce the need for service trips. One of the greatest challenges has been developing a method to interface Triton's WEC with these buoys without impacting measurement fidelity. This is especially critical for inertial wave and LiDAR wind measurements collected with sensors that could be adversely affected by additional buoy dynamics introduced by an integrated WEC. To address this, Triton and EOM Offshore developed a compliant tether to pair an observation buoy with a floating WEC while decoupling relative motion. Based on EOM's proven stretch hose technology, this compliant tether transmits power and data between the buoy-WEC system. In conclusion, modeling shows that the system has the potential to minimally adversely affect oceanographic, meteorological, wind resource characterization, and other measurements, with future testing scheduled to validate modeling efforts.

16 TIDAL AND WAVE POWER↗
NASA NTRS1973

Computer program for the load and trajectory analysis of two DOF bodies connected by an elastic tether: Users manual

The derivation of the differential equations of motion of a 3 Degrees of Freedom body joined to a 3 Degrees of Freedom body by an elastic tether. The tether is represented by a spring and dashpot in parallel. A computer program which integrates the equations of motion is also described. Although the derivation of the equations of motions are for a general system, the computer program is written for defining loads in large boosters recovered by parachutes.

Doyle, G. R., Jr.↗
NASA NTRS1975

A revolutionary and operational tethered aerostat system illustrating new LTA technology

An operational tethered aerostat system, which demonstrates utility of LTA systems, is described. It was made possible by development of a reliable tethered aerostat that is used to support broadcast equipment at an altitude of 10,000 feet. Two elements of the TCOM system, the aerostat and mooring station, are particularly relevant to the LTA Workshop. They demonstrate the feasibility of using LTA vehicles in real, operational, all-weather applications and, in addition, illustrate an advance in the overall technology base of LTA. The aerostat and the mooring station, including their technical design features and demonstrated performance characteristics, are described.

Menke, J. A.↗
NASA NTRS1976

Tethered balloon-based measurements of meteorological variables and aerosols

Tethered balloon based measurements of the vertical distributions of temperature, humidity, wind speed, and aerosol concentrations were taken over a 4-hour period beginning at sunrise on June 29, 1976, at Wallops Island, Virginia. Twelve consecutive profiles of each variable were obtained from ground to about 500 meters. These measurements were in conjuction with a noise propagation study on remotely arrayed acoustic range (ROMAAR) at Wallops Flight Center. An organized listing of these vertical soundings is presented. The tethered balloon system configuration utilized for these measurements is described.

Sentell, R. J.↗
NASA NTRS1979

A preliminary study of the attitude control for the Shuttle Tethered Satellite System

The objective of this investigation is to determine the equations of motion governing the attitude of a tethered satellite and subsequently to gain insight toward obtaining an appropriate control law. This study relates the coupling of the rotational dynamics of the satellite with the dynamical system of the Orbiter already constructed. In particular, a simplified approach is utilized to describe the satellite as constrained to planar motion. Modifications to the existing tethered satellite trajectory simulation provide a conceptual study of the satellite's behavior and its effect on the overall system.

Rupp, C. C.↗