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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 1,477 records · Page 82

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NASA NTRS1997

(abstract) Mars Pathfinder Active Thermal Control System: Ground and Flight Performance of a Mechanically Pumped Cooling Loop

A key element of the Mars Pathfinder thermal control system is the Heat Rejection System (HRS). The HRS of Mars Pathfinder is designed to actively control the temperatures of the various parts of the spacecraft.This is achieved by mechanically circulating single-phase Freon 11 liquid through the lander and cruise electronics box heat exchangers and transferring the heat to an external radiator on the cruise stage. This is the first time in spacecraft history that a mechanically pumped cooling loop has been used on a long duration spacecraft mission. Many lessons have been learned during the testing and ground and flight operation of the HRS. This paper will present the performance of the mechanically pumped cooling loop during the ground and flight operations. Based on the lessons learned from this experience, recommendations on the design and operation of the pumped cooling loops for future space missions will be made.

Mars↗

NASA NTRS2012

Simulated Lunar Testing of Metabolic Heat Regenerated Temperature Swing Adsorption

Metabolic heat regenerated Temperature Swing Adsorption (MTSA) technology is being developed for thermal and carbon dioxide (CO2) control for a Portable Life Support System (PLSS), as well as water recycling. An Engineering Development Unit (EDU) of the MTSA Subassembly (MTSAS) was designed and assembled for optimized Martian operations, but also meets system requirements for lunar operations. For lunar operations the MTSA sorption cycle is driven via a vacuum swing between suit ventilation loop pressure and lunar vacuum. The focus of this effort was testing in a simulated lunar environment. This environment was simulated in Paragon's EHF vacuum chamber. The objective of the testing was to evaluate the full cycle performance of the MTSA Subassembly EDU, and to assess CO2 loading and pressure drop of the wash coated aluminum reticulated foam sorbent bed. Lunar environment testing proved out the feasibility of pure vacuum swing operation, making MTSA a technology that can be tested and used on the Moon prior to going to Mars. Testing demonstrated better than expected CO2 Nomenclature loading on the sorbent and nearly replicates the equilibrium data from the sorbent manufacturer. This exceeded any of the previous sorbent loading tests performed by Paragon. Subsequently, the increased performance of the sorbent bed design indicates future designs will require less mass and volume than the current EDU rendering MTSA as very competitive for Martian PLSS applications.

Padilla, Sebastian A.↗

NASA NTRS2011

Material Studies Related to the Use of NaK Heat Exchangers Coupled to Stirling Heater Heads

NASA has been supporting design studies and technology development that could provide power to an outpost on the Moon, Mars, or an asteroid. Technology development efforts have included fabrication and evaluation of components used in a Stirling engine power conversion system. Destructive material evaluation was performed on a NaK shell heat exchanger that was developed by the NASA Glenn Research Center (GRC) and integrated with a commercial 1 kWe Stirling convertor from Sunpower Incorporated. The NaK Stirling test demonstrated Stirling convertor electrical power generation using a pumped liquid metal heat source under thermal conditions that represent the heat exchanger liquid metal loop in a Fission Power Systems (FPS) reactor. The convertors were operated for a total test time of 66 hr at a maximum temperature of 823 K. After the test was completed and NaK removed, the heat exchanger assembly was sectioned to evaluate any material interactions with the flowing liquid metal. Several dissimilar-metal braze joint options, crucial for the heat exchanger transfer path, were also investigated. A comprehensive investigation was completed and lessons learned for future heat exchanger development efforts are discussed.

Locci, Ivan E.↗

NASA NTRS2006

Dynamic Features in and nearby a Prominence

We will discuss the thermal and dynamic properties of dynamic structures in and around a prominence channel observed on the limb on 17 April 2003. Observations were taken with the Solar and Heliospheric Observatory's Solar Ultraviolet Measurements of Emitted Radiation (SOHO/SUMER) in lines formed at temperatures from 80,000 to 1.6 million K. The instrument was pointed to a single location and took a series of 90 s exposures. Two-dimensional context was provided by the Transition Region and Coronal Explorer (TRACE) in the UV and EUV and by the Kanzelhohe Solar Observatory in H-alpha. Two dynamic features were studied in depth: a prominence activation and repeated motions in a loop nearby the prominence. We were able to calculate three-dimensional geometries and trajectories, differential emission measure, and limits on the average density, kinetic and thermal energies. These observations provide important tests for models of dynamics in prominences and cool (approx.10(exp 5) K) loops.

Kucera, T.↗

NASA NTRS2026

Dynamic Regulation of Sub-Atmospheric Pressure for Constant and Cyclic Gas Loads During Testing of Spacesuit Components

New iterations of the various subsystems within the spacesuit will benefit from a new sorbent technology. For example, sorbents used in the Trace Contaminant Control (TCC) and the Rapid Cycle Amine (RCA) systems within the Exploration Portable Life Support System (xPLSS), part of the Extra-Vehicular Mobility Unit (xEMU). For proper validation, the sub-atmospheric pressure needs to be maintained within a simulated 2 ft 3 spacesuit volume. The traditional approach, which involves placing the entire vent loop within a hypobaric chamber, is not practical for the widespread testing of components and prototypes, as these specialized chambers are costly and not widely available. A two-stage regulator based sub-atmospheric pressure system is presented in this work. The method regulates the pressure based on pressure differentials between the pressure regulation pump, the test system, and the ambient environment. The performance of this system is demonstrated using data collected during a 150+ hour non-regenerative TCC sorbent evaluation, several 24-hour regenerative TCC sorbent evaluations with different regeneration cycles, and an 8-hour RCA sorbent evaluation, all under xEMU operating conditions. For regulation, the inlet regulator was set to propagate a small leak to increase the stability of the system as the gas load from the testing system changes. It was also found that controlling the input flow rate that replaces the material lost during regeneration is critical for ensuring the stability of the system. This system provided excellent pressure regulation, without adjustments, for constant loads during shorter time evaluations (hours), while longer time evaluations (days) are easily obtainable with periodic regulator adjustments. A second method is under development to address longer-term stability and to automate pressure regulation. It will incorporate flow and pressure measurements to dynamically control a set of electronically controlled proportional valves for adjusting the pumping speed and air bleed supply.

Nicholas F Materer↗

NASA NTRS2016

Human and Robotic Exploration Missions to Phobos Prior to Crewed Mars Surface Missions

Phobos is a scientifically significant destination that would facilitate the development and operation of the human Mars transportation infrastructure, unmanned cargo delivery systems and other Mars surface systems. In addition to developing systems relevant to Mars surface missions, Phobos offers engineering, operational, and public engagement opportunities that could enhance subsequent Mars surface operations. These opportunities include the use of low latency teleoperations to control Mars surface assets associated with exploration science, human landing‐site selection and infrastructure development which may include in situ resource utilization (ISRU) to provide liquid oxygen for the Mars Ascent Vehicle (MAV). A human mission to Mars' moons would be preceded by a cargo predeploy of a surface habitat and a pressurized excursion vehicle (PEV) to Mars orbit. Once in Mars orbit, the habitat and PEV would spiral to Phobos using solar electric propulsion based systems, with the habitat descending to the surface and the PEV remaining in orbit. When a crewed mission is launched to Phobos, it would include the remaining systems to support the crew during the Earth‐Mars transit and to reach Phobos after insertion in to Mars orbit. The crew would taxi from Mars orbit to Phobos to join with the predeployed systems in a spacecraft that is based on a MAV, dock with and transfer to the PEV in Phobos orbit, and descend in the PEV to the surface habitat. A static Phobos surface habitat was chosen as a baseline architecture, in combination with the PEV that was used to descend from orbit as the main exploration vehicle. The habitat would, however, have limited capability to relocate on the surface to shorten excursion distances required by the PEV during exploration and to provide rescue capability should the PEV become disabled. To supplement exploration capabilities of the PEV, the surface habitat would utilize deployable EVA support structures that allow astronauts to work from portable foot restraints or body restrain tethers in the vicinity of the habitat. Prototype structures were tested as part of NEEMO 20. PEVs would contain closed loop guidance and provide life support and consumables for two crew for 2 weeks plus reserves. The PEV has a cabin that uses the exploration atmosphere of 8.2 psi with 34% oxygen, enabling use of suit ports for rapid EVA with minimal oxygen prebreathe as well as dust control by keeping the suits outside the pressurized volume. When equipped with outriggers and control moment gyros, the PEV enables EVA tasks of up to 8 pounds of force application without the need to anchor. Tasks with higher force requirements can be performed with PEV propulsion providing the necessary thrust to react forces. Exploration of Phobos builds heavily from the developments of the cis‐lunar proving ground, and significantly reduces Mars surface risk by facilitating the development and testing of habitats, MAVs, and pressurized rover cabins that are all Mars surface forward. A robotic precursor mission to Phobos and Deimos is also under consideration and would need to launch in 2022 to support a 2031 human Phobos mission.

Gernhardt, Michael L.↗

DOE OSTI2022

A positive feedback loop involving the Spa2 SHD domain contributes to focal polarization

Focal polarization is necessary for finely arranged cell-cell interactions. The yeast mating projection, with its punctate polarisome, is a good model system for this process. We explored the critical role of the polarisome scaffold protein Spa2 during yeast mating with a hypothesis motivated by mathematical modeling and tested by in vivo experiments. Our simulations predicted that two positive feedback loops generate focal polarization, including a novel feedback pathway involving the N-terminal domain of Spa2. We characterized the latter using loss-of-function and gain-of-function mutants. The N-terminal region contains a Spa2 Homology Domain (SHD) which is conserved from yeast to humans, and when mutated largely reproduced the spa2Δ phenotype. Our work together with published data show that the SHD domain recruits Msb3/4 that stimulates Sec4-mediated transport of Bud6 to the polarisome. There, Bud6 activates Bni1-catalyzed actin cable formation, recruiting more Spa2 and completing the positive feedback loop. We demonstrate that disrupting this loop at any point results in morphological defects. Gain-of-function perturbations partially restored focal polarization in a spa2 loss-of-function mutant without restoring localization of upstream components, thus supporting the pathway order. Thus, we have collected data consistent with a novel positive feedback loop that contributes to focal polarization during pheromone-induced polarization in yeast.

59 BASIC BIOLOGICAL SCIENCES↗

DOE OSTI2024

Performance of the first mechanically-coupled twisting heliostat: encircled energy vs angle of incidence, and closed loop tracking

The first automatic twisting heliostat, with 8 m2 reflector, was completed and tested on-sun in January 2024. It was set up on a target-oriented dual-axis mount, with the target-axis aimed at a target 113 m to the west. The shape-twisting is purely automatic, made by a mechanical cam coupling to the cross-axis, which turns as the angle of incidence of the sun’s rays on the reflector. Three unsaturated images taken at different times of day were recorded of the sun on the target, reflected at angles of incidence of 5°, 49° and 68°. The measured FWHM of three images is very similar, about 1.09 m or 9.5 mrad, only slightly larger than an ideal solar disc, indicating that the different twisted reflector shapes are close to the ideal biconics needed to image the sun. The encircled energy measured for all three images was similar, 87% within approximately 1.30 m diameter. We report here also on a novel, tracking camera that employs a semitransparent beamsplitter fixed perpendicular to the mirror surface and to the plane of incidence. Over 2.5 hours of measurement of closed loop tracking, errors were ≤ 0.36 mrad rms, in both tracking axes.

14 SOLAR ENERGY↗

NASA NTRS1986

A flight test method for pilot/aircraft analysis

In high precision flight maneuvres a pilot is a part of a closed loop pilot/aircraft system. The assessment of the flying qualities is highly dependent on the closed loop characteristics related to precision maneuvres like approach, landing, air-to-air tracking, air-to-ground tracking, close formation flying and air-to air refueling of the receiver. The object of a research program at DFVLR is the final flight phase of an air to ground mission. In this flight phase the pilot has to align the aircraft with the target, correct small deviations from the target direction and keep the target in his sights for a specific time period. To investigate the dynamic behavior of the pilot-aircraft system a special ground attack flight test technique with a prolonged tracking maneuvres was developed. By changing the targets during the attack the pilot is forced to react continously on aiming errors in his sights. Thus the closed loop pilot/aircraft system is excited over a wide frequency range of interest, the pilot gets more information about mission oriented aircraft dynamics and suitable flight test data for a pilot/aircraft analysis can be generated.

Koehler, R.↗

NASA NTRS2015

Enhanced Flight Vision Systems Operational Feasibility Study Using Radar and Infrared Sensors

Approach and landing operations during periods of reduced visibility have plagued aircraft pilots since the beginning of aviation. Although techniques are currently available to mitigate some of the visibility conditions, these operations are still ultimately limited by the pilot's ability to "see" required visual landing references (e.g., markings and/or lights of threshold and touchdown zone) and require significant and costly ground infrastructure. Certified Enhanced Flight Vision Systems (EFVS) have shown promise to lift the obscuration veil. They allow the pilot to operate with enhanced vision, in lieu of natural vision, in the visual segment to enable equivalent visual operations (EVO). An aviation standards document was developed with industry and government consensus for using an EFVS for approach, landing, and rollout to a safe taxi speed in visibilities as low as 300 feet runway visual range (RVR). These new standards establish performance, integrity, availability, and safety requirements to operate in this regime without reliance on a pilot's or flight crew's natural vision by use of a fail-operational EFVS. A pilot-in-the-loop high-fidelity motion simulation study was conducted at NASA Langley Research Center to evaluate the operational feasibility, pilot workload, and pilot acceptability of conducting straight-in instrument approaches with published vertical guidance to landing, touchdown, and rollout to a safe taxi speed in visibility as low as 300 feet RVR by use of vision system technologies on a head-up display (HUD) without need or reliance on natural vision. Twelve crews flew various landing and departure scenarios in 1800, 1000, 700, and 300 RVR. This paper details the non-normal results of the study including objective and subjective measures of performance and acceptability. The study validated the operational feasibility of approach and departure operations and success was independent of visibility conditions. Failures were handled within the lateral confines of the runway for all conditions tested. The fail-operational concept with pilot in the loop needs further study.

Etherington, Timothy J.↗

NASA NTRS2013

Closed-Loop Analysis of Soft Decisions for Serial Links

We describe the benefit of using closed-loop measurements for a radio receiver paired with a counterpart transmitter. We show that real-time analysis of the soft decision output of a receiver can provide rich and relevant insight far beyond the traditional hard-decision bit error rate (BER) test statistic. We describe a Soft Decision Analyzer (SDA) implementation for closed-loop measurements on single- or dual- (orthogonal) channel serial data communication links. The analyzer has been used to identify, quantify, and prioritize contributors to implementation loss in live-time during the development of software defined radios. This test technique gains importance as modern receivers are providing soft decision symbol synchronization as radio links are challenged to push more data and more protocol overhead through noisier channels, and software-defined radios (SDRs) use error-correction codes that approach Shannon's theoretical limit of performance.

Lansdowne, Chatwin A.↗

NASA NTRS2013

Soft Decision Analyzer

Lansdowne, Chatwin↗

DOE OSTI2024

Comparison of hardening and microstructures of ferritic/martensitic steels irradiated with fast neutrons and dual ions

Ferritic/martensitic steels T91 and HT9 were irradiated with neutrons (BOR-60 reactor) and dual ions (9 MeV Fe 3+ and 3.42 MeV energy degraded He 2+ ) from 369 to 520 °C and damage levels of 16.6 to 72 dpa to quantify the possibility of using ion irradiation to simulate neutron irradiation in terms of microstructures and mechanical properties. Nanoindentation testing was performed to obtain the bulk equivalent hardness of the dual-ion irradiated samples. For the neutron irradiated samples, both nanoindentation and Vickers hardness testing were conducted. Transmission Electron Microscopy (TEM) characterizations of the cavities, dislocation loops and precipitates were conducted to account for the strengthening contribution of each microstructure element. The good agreement between the microstructure-predicted (dispersed barrier hardening) and measured strength of the irradiated specimens demonstrated the accuracy of the strengthening model and the nanoindentation tests. Furthermore, the comparison of mechanical property and microstructure changes in ion and neutron irradiated structural materials indicated that ion irradiation replicated many neutron irradiation features. However, a single 70 °C temperature shift is insufficient to match all complex microstructures of neutron vs. ion irradiation over the irradiation temperature range of 369–520 °C.

36 MATERIALS SCIENCE↗

NASA NTRS2013

Leak Mitigation in Mechanically Pumped Fluid Loops for Long Duration Space Missions

Mechanically pumped fluid loops (MPFLs) are increasingly considered for spacecraft thermal control. A concern for long duration space missions is the leak of fluid leading to performance degradation or potential loop failure. An understanding of leak rate through analysis, as well as destructive and non-destructive testing, provides a verifiable means to quantify leak rates. The system can be appropriately designed to maintain safe operating pressures and temperatures throughout the mission. Two MPFLs on the Mars Science Laboratory Spacecraft, launched November 26, 2011, maintain the temperature of sensitive electronics and science instruments within a -40 deg C to 50 deg C range during launch, cruise, and Mars surface operations. With over 100 meters of complex tubing, fittings, joints, flex lines, and pumps, the system must maintain a minimum pressure through all phases of the mission to provide appropriate performance. This paper describes the process of design, qualification, test, verification, and validation of the components and assemblies employed to minimize risks associated with excessive fluid leaks from pumped fluid loop systems.

thermal controls↗

DOE OSTI2026

Climate impacts in scenarios: time to close the loop?

Reaching a full understanding of the consequences of climate change for society and ecosystems, and the ensuing needs for adaptation, requires a consideration of the interactions between human and Earth systems. Currently, however, climate research largely separates the influence of society on climate from the influence of climate on society; that is, it doesn’t “close the loop.” A primary example of this approach is the generation and use of earth system model (ESM) simulations in the climate change research community. Large-scale socio-economic models, known as integrated assessment models (IAMs), are used to project emissions and land use change which serve as input to ESMs. ESM projections then serve as input to models of impacts on society and ecosystems. But, according to this modeling chain, those impacts do not affect the emissions and land use that drove the ESMs in the first place. Previous work has not drawn firm conclusions on whether this feedback would be large enough to warrant explicitly accounting for it. Two prominent possibilities, however, are that emissions and land use scenarios representing the high and low ends of the plausible range of future climate change are both too extreme. The high-end scenario may miss damaging impacts that would reduce economic activity, and therefore emissions, while the low-end scenario may ignore climate feedbacks that would make large-scale land-based carbon removal ineffective and therefore would hamper mitigation at the level assumed by the scenario. In this piece, we identify the opportunities and challenges that implementing such feedback loops would face. We argue that recent developments in climate impact research, human system modeling and ESM emulation make the time ripe to use IAMs in a structured model intercomparison exercise. Model intercomparison projects have benefitted the climate modeling community for decade snow, and more recently have also benefitted the impact modeling community. An IAM intercomparison focused on integrating impacts could make large strides in testing the implications of these feedbacks and assessing whether closing the loop would fundamentally change our outlook on future climate changes and their consequences.

Tebaldi, Claudia↗

NASA NTRS2007

Demonstration of Metabolic Heat Regenerated Temperature Swing Adsorption Technology

Patent-pending Metabolic heat regenerated Temperature Swing Adsorption (MTSA) technology is currently being investigated for removal and rejection of CO2 and heat from a Portable Life Support System (PLSS) to a Martian environment. The metabolically-produced CO2 present in the vent loop gas is collected using a CO2 selective adsorbent that has been cooled via a heat exchanger to near CO2 sublimation temperatures (approx.195K) with liquid CO2 obtained from Martian resources. Once the adsorbent is fully loaded, fresh warm, moist vent loop (approx.300K) is used to heat the adsorbent via another heat exchanger. The adsorbent will then reject the collected CO2 to the Martian ambient. Two beds are used to achieve continuous CO2 removal by cycling between the cold and warm conditions for adsorbent loading and regeneration, respectively. Small experiments have already been completed to show that an adsorbent can be cycled between these PLSS operating conditions to provide adequate conditions for CO2 removal from a simulated vent loop. One of the remaining technical challenges is extracting enough heat from the vent loop to warm the adsorbent in an appreciable time frame to meet the required adsorb/desorb cycle. The other key technical aspect of the technology is employing liquid CO2 to achieve the appropriate cooling. A technology demonstrator has been designed, built and tested to investigate the feasibility of 1) warming the adsorbent using the moist vent loop, 2) cooling the adsorbent using liquid CO2, and 3) using these two methods in conjunction to successfully remove CO2 from a vent loop and reject it to Mars ambient. Both analytical and numerical methods were used to perform design calculations and trades. The demonstrator was built and tested. The design analysis and testing results are presented along with recommendations for future development required to increase the maturity of the technology.

Paul, Heather↗

DOE OSTI2020

Model predictive control of KSTAR equilibrium parameters enabled by TRANSP

Due to the complex behavior of tokamak plasmas and the importance of optimizing performance while avoiding instabilities and machine limits, plasma control algorithms are becoming increasingly dependent on sophisticated model-based control approaches. It is anticipated that the use of integrated modeling codes in the model-based control design process will reduce the amount of experimental time needed to implement new control algorithms by facilitating development of control-oriented models and enabling higher-fidelity closed-loop simulations. In this work, a reduced model is developed from a series of TRANSP simulations and is used to develop a model predictive control (MPC) algorithm for controlling important equilibrium parameters in KSTAR [1] discharges. The control algorithm uses the KSTAR neutral beam injection system and the target plasma current and plasma boundary as actuators, and optimizes the plasma stored energy, loop voltage, and internal inductance while avoiding constraints that could lead to disruptions. Higher fidelity testing of the control algorithm is performed using a flexible framework for enabling external processes to actively control plasma parameters in TRANSP simulations. Furthermore, closed-loop simulations demonstrate the ability of the control algorithm to respond to disturbances in density and confinement, handle actuator failures, and move the discharge to high non-inductive fraction conditions.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗

NASA NTRS2003

Improved Testing Capability and Adaptability Through the Use of Wireless Sensors

From the first Saturn V rocket booster (S-II-T) testing in 1966 and the routine Space Shuttle Main Engine (SSME) testing beginning in 1975, to more recent test programs such as the X-33 Aerospike Engine, the Integrated Powerhead Development (IPD) program, and the Hybrid Sounding Rocket (HYSR), Stennis Space Center (SSC) continues to be a premier location for conducting large-scale testing. Central to each test program is the capability for sensor systems to deliver reliable measurements and high quality data, while also providing a means to monitor the test stand area to the highest degree of safety and sustainability. Sensor wiring is routed along piping and through cable trenches, making its way from the engine test area, through the test stand area and to the signal conditioning building before final transfer to the test control center. When sensor requirements lie outside the reach of the routine sensor cable routing, the use of wireless sensor networks becomes particularly attractive due to their versatility and ease of installation. As part of an on-going effort to enhance the testing capabilities of Stennis Space Center, the Test Technology and Development group has found numerous applications for its sensor-adaptable wireless sensor suite. While not intended for critical engine measurements or control loops, in-house hardware and software development of the sensor suite can provide improved testing capability for a range of applications including the safety monitoring of propellant storage barrels and as an experimental test-bed for embedded health monitoring paradigms.

Solano, Wanda M.↗