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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 127 records · Page 7
All sourcesNASA NTRSDOE OSTI
NASA NTRS1996

Daily Supine LBNP Treadmill Exercise Maintains Upright Exercise Capacity During 14 Days of Bed Rest

Exposure to microgravity or bed rest reduces upright exercise capacity. Exercise modes, durations, and intensities which will effectively and efficiently counteract such deconditioning are presently unresolved. We that daily supine treadmill interval training with lower body negative pressure (LBNP) would prevent reduction in upright exercise capacity during 14 days of 6 deg. head-down bed rest (BR). Eight healthy male subjects underwent two 14 day BR protocols separated by 3 months. In a crossover design, subjects either remained at strict BR or performed 40 min of daily exercise consisting of supine walking and running at intensities varying from 40-80% of pre-BR upright peak oxygen uptake (VO2). LBNP during supine exercise was used to provide 1.0 to 1.2 times body weight of footward force. An incremental upright treadmill test to measure submaximal and peak exercise responses was given pre- and post-BR. In the non-exercise condition, peak VO2 and time to exhaustion were reduced 16 +/- 4% and 10 +/- 1% (p less than 0.05), respectively, from pre-BR. With LBNP exercise these variables were not significantly different (NS) from pre-BR. During submaximal treadmill speeds after BR, heart rate was higher (11 +/- 11 bpm, p less than 0.05) and respiratory exchange ratio was elevated (p less than 0.05) in the no exercise condition. Both were maintained at pre-BR levels in the LBNP exercise condition (NS from pre-BR). Since this supine treadmill interval training with addition of LBNP maintained upright exercise responses and capacity during BR, this countermeasure may also be effective during space flight.

Ertl, Andy C.↗
NASA NTRS1995

Balancing photosynthetic light-harvesting and light-utilization capacities in potato leaf tissue during acclimation to different growth temperatures

We investigated the effect of temperature during growth and development on the relationship between light-harvesting capacity, indicated by chlorophyll concentration, and light-utilization potential, indicated by light- and bicarbonate-saturated photosynthetic oxygen evolution, in Solanum tuberosum L. cv. Norland. Clonal plantlets were transplanted and grown at 20 degrees C for 2 weeks before transfer to 12, 16, 20, 24 and 28 degrees C for 6 weeks. After 4 weeks of the temperature treatments, leaf tissue fresh weights per area were one-third higher in plants grown at 12 degrees C vs those grown at 28 degrees C. Conversely, chlorophyll content per area in tissue grown at 12 degrees C was less than one-half of that of tissue grown at 28 degrees C at 4 weeks. Photosynthetic capacity measured at a common temperature of 20 degrees C and expressed on a chlorophyll basis was inversely proportional to growth temperature. Leaf tissue from plants grown at 12 degrees C for 4 weeks had photosynthetic rates that were 3-fold higher on a chlorophyll basis than comparable tissue from plants grown at 28 degrees C. These results suggest that the relationship between light-harvesting capacity and light-utilization potential varies 3-fold in response to the growth temperatures examined. The role of this response in avoidance of photoinhibition is discussed.

NASA Center KSC↗
NASA NTRS1997

Pulmonary tissue volume, cardiac output, and diffusing capacity in sustained microgravity

In microgravity (microG) humans have marked changes in body fluids, with a combination of an overall fluid loss and a redistribution of fluids in the cranial direction. We investigated whether interstitial pulmonary edema develops as a result of a headward fluid shift or whether pulmonary tissue fluid volume is reduced as a result of the overall loss of body fluid. We measured pulmonary tissue volume (Vti), capillary blood flow, and diffusing capacity in four subjects before, during, and after 10 days of exposure to microG during spaceflight. Measurements were made by rebreathing a gas mixture containing small amounts of acetylene, carbon monoxide, and argon. Measurements made early in flight in two subjects showed no change in Vti despite large increases in stroke volume (40%) and diffusing capacity (13%) consistent with increased pulmonary capillary blood volume. Late in-flight measurements in four subjects showed a 25% reduction in Vti compared with preflight controls (P < 0.001). There was a concomittant reduction in stroke volume, to the extent that it was no longer significantly different from preflight control. Diffusing capacity remained elevated (11%; P < 0.05) late in flight. These findings suggest that, despite increased pulmonary perfusion and pulmonary capillary blood volume, interstitial pulmonary edema does not result from exposure to microG.

Clinical Trial↗
NASA NTRS2006

Large Array Channel Capacity in the Presence of Interference

We develop a model for a large array ground receiver system for use in deep-space communications, and analyze the resulting array channel capacity. The model includes effects of array geometry, time-dependent spacecraft orbital trajectory, point and extended interference sources, and elevation-dependent noise and tropospheric channel variations. Channel capacity is expressed as the ratio of determinants of covariance matrices characterizing source, interference, and additive noise, and then reduced to a simpler quadratic form more amenable to analysis and numerical computation. This formulation facilitates inclusion of array and channel characteristics into the model, as well as comparison of optimal, suboptimal, and equivalent single antenna configurations on achievable throughput. Realistic examples of ground array channel capacity calculations are presented, demonstrating the impact of array geometry, planetary interference sources, and array combining algorithm design upon the achievable data throughput.

Vilnrotter, V.↗
NASA NTRS2006

High Capacity Communications From Martian Distances: Spacecraft Link Design Analysis - Part 1

High capacity space communications has been a desire for Human Exploration and Science missions. Current Mars missions operate at data rates of 120 kbps for telemetry downlink and it is desirable to study high rate communication links in the range of 100 Mbps to 1 Gbps data rates from Martian distances. This paper will present some assumed scenarios along with link design assumptions and link analysis for high capacity communications from Mars. The paper will focus on RF subsystems namely antenna and power for the downlink communication from a relay orbiter at Mars. The relay orbiter will communicate with the low orbit spacecrafts at Mars or any Martian surface elements such as robots, and relay the data back to the ground networks on Earth. The study will dive into the spacecraft downlink system design and communication link analysis between the relay orbiter and ground network on Earth for data rates ranging from 100 Mbps to 1 Gbps based on the assumed scenarios and link assumptions. With high rate links at larger distances, there will be a significant impact on the antenna and power requirements and the link design will make an attempt to minimize the mass of the RF subsystem on the spacecraft. The results of this study will be presented for three data rates 1 Gbps, 500 Mbps and 100 Mbps at maximum Mars to Earth distance of 2.67AU. The design will use a Ka-band downlink with 90% link availability, along with various ground network G/T assumptions and possible bandwidth efficient modulations. The paper will conclude with what types of high rate communication links are feasible from Martian distances and also identify a range of requirements for antenna and power technologies for these high capacity communications from Mars.

Ka-Band communications↗
NASA NTRS2006

WISE-2005: LBNP/Treadmill and Resistive Exercise Countermeasures Maintain Aerobic Capacity during a 60-d Bed Rest

We have previously documented that supine treadmill exercise within lower body negative pressure (LBNPex) performed 6 sessions (raised dot) wk(sup -1) during 15- and 30-day bed rests (BR) maintained upright aerobic capacity (VO2pk). In the present study, ure are evaluating whether aerobic capacity is maintained during a 60-d BR when the LBNPex frequency is reduced to 2-4 sessions (raised dot) wk(sup -1) and resistance exercise (REX) is added 2-3 sessions (raised dot) wk(sup -1). Eight healthy women (32 plus or minus 4 yrs; 56.4 plus or minus 3.6 kg; 164 plus or minus 8 cm; mean plus or minus SD) performed maximal-exertion, graded treadmill tests before and 3 days after a 60-d, 6 deg. head-down tilt BR. (Earliest day the medical monitors would permit a maximal exercise test post-BR). During BR, four subjects performed no exercise (CON), while four other subjects (EX) performed LBNPex and REX on separate days. The LBNPex countermeasure employed an intermittent (40-80% pre-BR VO2pk), 40-min protocol against an LBNP pressure (-49 plus or minus 3 mmHg) applied to provide a footward force equivalent to 1.0-1.2 body weight. REX consisted of maximal concentric and eccentric supine leg press and heel raise exercises using a gravity-independent flywheel ergometer. Comparisons were performed using paired (within-group) or non-paired (between-group) t-tests. Three days post-BR, VO2pk of the CON group was reduced significantly from pre-BR (Pre:37.2 plus or minus 1.2, Post: 29.4 plus or minus 2 ml (raised dot) kg(sup -1) (raised dot) min(sup -1), P less than 0.05), while the VO2pk of the EX group was not significantly reduced (Pre: 39.6 plus or minus 1.9, Post: 38.0 plus or minus 0.6 ml (raised dot) kg(sup -1) (raised dot) min(sup -1)). Peak heart rate, ventilation, rating of perceived exertion, and respiratory exchange ratio were not significantly different between the two groups pre- and post-BR. These preliminary results suggest that the combined LBNPex and REX countermeasures may be sufficient to maintain upright aerobic capacity after long-duration space flights.

Schneider, Suzanne M.↗
NASA NTRS2010

Integrated Analysis of Airport Capacity and Environmental Constraints

LMI conducted an integrated analysis of airport capacity and environmental constraints. identifying and ranking the key factors limiting achievement of NextGen capacity goals. The primary metric used was projected throughput, which was estimated for the years 2015 and 2025 based on the unconstrained demand forecast from the Federal Aviation Administration, and planned improvements including those proposed in the NextGen plan. A set of 310 critical airports was identified.. collectively accounting for more than 99 percent of domestic air traffic volume; a one-off analytical approach was used to isolate the constraint being assessed. The study considered three capacity constraints (runway.. taxiway, and gate) and three environmental constraints (fuel, NO(x) emissions, and noise). For the ten busiest airports, runway and noise are the primary and secondary constraints in both 2015 and 2025. For the OEP 35 airports and overall for the remaining airports, the most binding constraint is noise. Six of the 10 busiest airports, will face runway constraints in 2025, and 95 will face gate constraints. Nearly every airport will be subject to constraints due to emissions and NOx. Runway and taxi constraints are more concentrated in the large airports: environmental constraints are present at almost every airport regardless of size.

Hasan, Shahab↗
NASA NTRS2010

Capacity Maximizing Constellations

Some non-traditional signal constellations have been proposed for transmission of data over the Additive White Gaussian Noise (AWGN) channel using such channel-capacity-approaching codes as low-density parity-check (LDPC) or turbo codes. Computational simulations have shown performance gains of more than 1 dB over traditional constellations. These gains could be translated to bandwidth- efficient communications, variously, over longer distances, using less power, or using smaller antennas. The proposed constellations have been used in a bit-interleaved coded modulation system employing state-ofthe-art LDPC codes. In computational simulations, these constellations were shown to afford performance gains over traditional constellations as predicted by the gap between the parallel decoding capacity of the constellations and the Gaussian capacity

Barsoum, Maged↗
NASA NTRS2010

High voltage and high specific capacity dual intercalating electrode Li-ion batteries

The present invention provides high capacity and high voltage Li-ion batteries that have a carbonaceous cathode and a nonaqueous electrolyte solution comprising LiF salt and an anion receptor that binds the fluoride ion. The batteries can comprise dual intercalating electrode Li ion batteries. Methods of the present invention use a cathode and electrode pair, wherein each of the electrodes reversibly intercalate ions provided by a LiF salt to make a high voltage and high specific capacity dual intercalating electrode Li-ion battery. The present methods and systems provide high-capacity batteries particularly useful in powering devices where minimizing battery mass is important.

West, William C.↗
NASA NTRS2010

Managing Demand and Capacity Using Multi-Sector Planning and Flexible Airspace: Human-in-the-Loop Evaluation of NextGen

When demand for an airspace sector exceeds capacity, the balance can be re-established by reducing the demand, increasing the capacity, or both. The Multi-Sector Planner (MSP) concept has been proposed to better manage traffic demand by modifying trajectories across multiple sectors. A complementary approach to MSP, called Flexible Airspace Management (FAM), reconfigures the airspace such that capacity can be reallocated dynamically to balance the traffic demand across multiple sectors, resulting in fewer traffic management initiatives. The two concepts have been evaluated with a series of human-in-the-loop simulations at the Airspace Operations Laboratory to examine and refine the roles of the human operators in these concepts, as well as their tools and procedural requirements. So far MSP and FAM functions have been evaluated individually but the integration of the two functions is desirable since there are significant overlaps in their goals, geographic/temporal scope of the problem space, and the implementation timeframe. Ongoing research is planned to refine the humans roles in the integrated concept.

Lee, Paul U.↗
NASA NTRS2012

SERVIR Science Applications for Capacity Building

SERVIR is a regional visualization and monitoring system using Earth observations to support environmental management, climate adaptation, and disaster response in developing countries. SERVIR is jointly sponsored by NASA and the U.S. Agency for International Development (USAID). SERVIR has been instrumental in development of science applications to support the decision-making and capacity building in the developing countries with the help of SERVIR Hubs. In 2011, NASA Research Opportunities in Space and Earth Sciences (ROSES) included a call for proposals to form SERVIR Applied Sciences Team (SERVIR AST) under Applied Sciences Capacity Building Program. Eleven proposals were selected, the Principal Investigators of which comprise the core of the SERVIR AST. The expertise on the Team span several societal benefit areas including agriculture, disasters, public health and air quality, water, climate and terrestrial carbon assessments. This presentation will cover the existing SERVIR science applications, capacity building components, overview of SERVIR AST projects, and anticipated impacts.

Limaye, Ashutosh↗
NASA NTRS2014

Investigation of Metal Oxide/Carbon Nano Material as Anode for High Capacity Lithium-ion Cells

NASA is developing high specific energy and high specific capacity lithium-ion battery (LIB) technology for future NASA missions. Current state-of-art LIBs have issues in terms of safety and thermal stability, and are reaching limits in specific energy capability based on the electrochemical materials selected. For example, the graphite anode has a limited capability to store Li since the theoretical capacity of graphite is 372 mAh/g. To achieve higher specific capacity and energy density, and to improve safety for current LIBs, alternative advanced anode, cathode, and electrolyte materials are pursued under the NASA Advanced Space Power System Project. In this study, the nanostructed metal oxide, such as Fe2O3 on carbon nanotubes (CNT) composite as an LIB anode has been investigated.

battery performance↗
NASA NTRS2017

Thermophysical Properties of Cold and Vacuum Plasma Sprayed Cu-Cr-X Alloys, NiAl and NiCrAlY Coatings: Specific Heat Capacity - Part 2

Part I of the paper discussed the temperature dependencies of the electrical resistivities, thermal conductivities, thermal diffusivities and total hemispherical emissivities of several vacuum plasma sprayed (VPS) and cold sprayed copper alloy monolithic coatings, VPS NiAl, VPS NiCrAlY, extruded GRCop-84 and as-cast Cu-17(wt.%)Cr-5%Al. Part II discusses the temperature dependencies of the constant pressure specific heat capacities, CP, of these coatings. The data were empirically were regression-fitted with the equation: CP = AT4 + BT3 + CT2 + DT +E where T is the absolute temperature and A, B, C, D and E are regression constants. The temperature dependencies of the molar enthalpy, molar entropy and Gibbs molar free energy determined from experimental values of molar specific heat capacity are reported. Calculated values of CP using the Neumann-Kopp (NK) rule were in poor agreement with experimental data. Instead, a modification of the Neumann-Kopp rule was found to predict values closer to the experimental data with an absolute deviation less than 6.5%. The specific molar heat capacities for all the alloys did not agree with the Dulong-Petit law, and CP is greater than 3R, where R is the universal gas constant, were measured for all the alloys except NiAl for which CP is less than 3R at all temperatures.

Raj, S. V.↗
NASA NTRS2017

CO2 Capacity Sorbent Analysis using Volumetric Measurement Approach

In support of air revitalization system sorbent selection for future space missions, Ames Research Center (ARC) has performed CO2 capacity tests on various sorbents to complement structural strength tests from Marshall Space Flight Center (MSFC). The materials of interest are: Grace Davison Grade 544 13x, Honeywell UOP APG III, VSA-10, BASF 13x, and Grace Davison Grade 522 5A. Each sorbents CO2 capacity was measured using a Micromeritics ASAP 2020 Physisorption Volumetric Analysis machine to produce 0C, 10C, 25C, 50C, and 75C isotherms. These datasets were then extrapolated using Langmuir 3-Site and Toth isotherm models to compare with previously measured capacity data from MSFC using a thermogravimetric analysis approach. The modeling and extrapolation from ARC data correlated well with data measured at MSFC.

Air Revitalization↗
NASA NTRS2019

Testbed for Characterizing the Adsorptive Capacities of Pleated Panel Filters

Pleated panel filters offer a new commercial form factor for controlling VOCs in spacecraft cabin air. They differ from conventional commercial granular activated carbons because they have a lower pressure drop across the filter. A testbed was developed for evaluating the removal capacities of commercial pleated panel filters for NH3. The adsorptive capacity of a commercial cation-exchange pleated filter was compared versus the adsorptive capacities of two acid- impregnated activated carbons used for controlling ammonia in spacecraft cabin air.

Monje Mejia, Oscar A.↗
NASA NTRS2019

Development of Solid State Electrolytes for Li-Metal Based High Capacity Battery

NASA future missions demand safe, high specific energy (>400 Wh/kg) batteries. Current state-of-the-art (SOA) lithium-ion batteries (LIBs) can only provide ~150-200 Wh/kg in energy capacity, which is unable to meet NASA's future energy goals, and also pose safety issues due to the use of liquid flammable electrolyte. There are intense on-going development activities to increase battery energy density. The use of Li metal as an anode material has emerged as one highly attractive option for achieving high-energy, next generation batteries. This is because Li has many advantages. It is the lightest metal, but also has the highest theoretical capacity. It also has the lowest potential, which boosts whole cell voltage, and Li metal is 100% active material and requires no binder. Thus, Li metal is an ideal anode material for high energy battery chemistries. Lithium metal based advanced battery chemistries are envisioned to be mission enhancing and, in many cases, mission enabling for future space and aeronautic applications. However, the reliable use of this exceptionally high capacity anode in a commercial rechargeable battery has not been achieved due to safety and reliability concerns resulting from thermal runaway and short-circuit issues due to dendritic growth on the Li metal anode from lithium plating during charge-discharge cycles. A solid state electrolyte, such as garnet/ceramic or solid polymer nanocomposite electrolyte, is a promising approach to make Li metal safely cycling. The solid state electrolyte is non-flammable and eliminates leakage and fire hazard by replacing the liquid flammable electrolyte. However, the low-ionic conductivity and high interfacial impedance are the key issues to be overcome. In this presentation, the research activities on solid state electrolyte development funded by the NASA Advanced Energy Storage System program and by the NASA Center Innovative Fund will be presented, and the progress and results will be also discussed.

Wu, James J.↗
NASA NTRS2020

Excess Heat Capacity in Mo/Au Transition Edge Sensor Bolometric Detectors

Excessheat capacity in a bolometric detector has the consequence of increasing or leading to multiple device time con-stants.The Mo/Au bilayer transition edge sensor (TES) bolo-metric detectors intended for the high resolution mid-infrared spectrometer (HIRMES) have two response time, one of which is a few times longer than that estimated from materials used in the design. The relative contribution of this settling time to the overall time response of the detectors is roughly proportional with the pixel area, which ranges between ~0.3 and 2.6 mm2.Use of laser ablation to remove sections of the silicon membranes comprising the pixels results in a detector response with a smaller contribution from the secondary time constant.Additional information about the nature of this excess heat capacity is gleaned from glancing in-cidence x-ray diffraction, which reveals the presence of molyb-denum silicides near the silicon surface from the bi-layer deposi-tion.Quantitative analysis of the concentration of excess molyb-denum, estimated with secondary ion mass spectroscopy, is com-mensurate to the additional heat capacity needed to explain the anomalous time response of the detectors.

HIRMES↗
NASA NTRS2020

High-capacity ATHLETE Offloader Mobility Constructor Concept for Human Surface Exploration

Using cross-cabled, winch-tendon four-bar frames, a new Artemis-class ATHLETE system is a multi-limbed robotic mobility platform that is designed for surface traverse, precision placement, and offloading of heavy habitats and other large human exploration payloads from high-decked landers. Building upon lessons learned from the All-Terrain Hex-Limbed Extra-Terrestrial Explorer (ATHLETE) robotic mobility system developed for Constellation Lunar Surface Systems and Evolvable Mars Campaign, a high-capacity articulated crane / lift vehicle concept has been devised that would be equipped with multi-limb six-degree-of-freedom dexterity for a variety of tasks supporting planetary surface human exploration missions and outposts. The Artemis-class ATHLETE vehicle would use any combination of three to six wheel-onlimb combinations to provide a wide “outrigger” stance to transfer loads from a high center-of-gravity on sloped terrain to low stable carry configurations for long-distance traverses, and be capable of precision docking of payloads to previously positioned elements. The new vehicle concept improves upon previous Constellation-class ATHLETE versions by allowing modular hot-swapping of individual limbs to improve maintenance and flexibility. The extreme-capacity independent limbs can individually function as single cranes, and can be delivered separately via multiple lander manifests for later congregation into self-driving “Tri-ATHLETE” vehicles after delivery to the surface. This paper provides mission architecture targets and vehicle masses for stepped payload capacity values in Earth, Mars, and Lunar gravity environments, and discusses a variety of swappable tools, including wheeled mobility attachments, grippers, excavation tools, repair fixtures, ISRU extraction, winches, block & tackle rigging combinations, 3D printheads, and construction aids.

Wilcox, Brian↗