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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 91 records · Page 5
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NASA NTRS2024

Artemis I Optical Navigation System Performance

This paper summarizes the assessment of the Optical Navigation Flight Test Objective (FTO) during the flight of Artemis I. The Optical Navigation (OpNav) System was tested under a variety of range, target, and lighting conditions to evaluate the performance compared to the pre-flight predicted error models. In general, OpNav performed very well – successfully processing over a thousand images of starfields, Earth, and Moon. The performance of the algorithm when processing Moon images matched the pre-flight expected error models. The errors when processing Earth images were notably higher than the pre-flight models predicted, however this was found to be due to an over-estimation of the atmosphere bias used in the tuning of the algorithm. After the bias was re-tuned and the images reprocessed, performance significantly improved.

GNC↗
NASA NTRS2001

Utilization of an Airborne Plant Chlorophyll Imaging System for Detection of Septic System Malfunction

Malfunctioning, or leaking, sewer systems increase the supply of water and nutrients to surface vegetation. Excess nutrients and harmful bacteria in the effluent pollute ground water and local water bodies and are dangerous to humans and the aquatic ecosystems. An airborne multispectral plant chlorophyll imaging system (PCIS) was used to identify growth patterns in the vegetation covering onsite and public sewer systems. The objective was to evaluate overall performance of the PCIS as well as to determine the best operational configuration for this application. The imaging system was flown in a light aircraft over selected locations Mobile County, Alabama. Calibration panels were used to help characterize instrument performance. Results demonstrated that the PCIS performed well and was capable of detecting septic leakage patterns from altitudes as high as 915 m. From 915 m, 6 of 18 sites were suspected to have sewage leakage. Subsequent ground inspections confirmed leakage on 3 of the 6 sites. From 610 m, 3 of 8 known leakage sites were detected. Tree cover and shadows near residential structures prevented detection of several known malfunctioning systems. Also some leakages known to occur in clear areas were not detected. False detections occurred in areas characterized by surface water drainage problems or recent excavation.

Spiering, Bruce A.↗
NASA NTRS1995

Lightweight, light-trapped, thin GaAs solar cell for spacecraft applications: Progress and results update

Progress is reported with respect to the development of ultra-lightweight, high performance, thin, light trapped GaAs solar cells for advanced space power systems. Conversion efficiencies of over 17.7% have been demonstrated for a 3 micron thick, 1 sq cm silicone bonded solar cell. This results in a specific power of over 1020 W/kg. Device parameters were 1.011 V open circuit voltage, 80% fill factor, and a short-circuit current density of 29.5 mA/sq cm . In addition to silicone bonding, the use of electrostatic bonding to attach the coverglass support to the front surface enables an ultra-thin, all back contact design that survives processing temperatures greater than 750 C. This also results in a 10% reduction of the cell weight for a potential specific power of 1270 W/kg. All back contact, ultra-thin, electrostatically bonded GaAs solar cell prototypes have been completed demonstrating an open circuit voltage of 1 volt for a cell base thickness of 1 micron with a 0.5 micron emitter. This technology will result in a revolutionary improvement in survivability, performance, and manufacturability of lightweight GaAs solar cell products for future Earth-orbiting science and space exploration missions. The thin, electrostatically bonded, all back contact GaAs device technology has multiple uses for specialty high performance solar cells and other optoelectronic devices.

Hannon, M. H.↗
NASA NTRS1978

Self-scanned photodiode array - High performance operation in high dispersion astronomical spectrophotometry

A multichannel spectrophotometric detector system has been developed using a 1024 element self-scanned silicon photodiode array, which is now in routine operation with the high-dispersion coude spectrograph of the University of Texas McDonald Observatory 2.7-m telescope. Operational considerations in the use of such arrays for high precision and low light level spectrophotometry are discussed. A detailed description of the system is presented. Performance of the detector as measured in the laboratory and on astronomical program objects is described, and it is shown that these arrays are highly effective detectors for high dispersion astronomical spectroscopy.

Vogt, S. S.↗
NASA NTRS1991

Multivariable control of the Space Shuttle remote manipulator system using H2 and H(infinity) optimization

Three linear controllers are desiged to regulate the end effector of the Space Shuttle Remote Manipulator System (SRMS) operating in Position Hold Mode. In this mode of operation, jet firings of the Orbiter can be treated as disturbances while the controller tries to keep the end effector stationary in an orbiter-fixed reference frame. The three design techniques used include: the Linear Quadratic Regulator (LQR), H2 optimization, and H-infinity optimization. The nonlinear SRMS is linearized by modelling the effects of the significant nonlinearities as uncertain parameters. Each regulator design is evaluated for robust stability in light of the parametric uncertanties using both the small gain theorem with an H-infinity norm and the less conservative micro-analysis test. All three regulator designs offer significant improvement over the current system on the nominal plant. Unfortunately, even after dropping performance requirements and designing exclusively for robust stability, robust stability cannot be achieved. The SRMS suffers from lightly damped poles with real parametric uncertainties. Such a system renders the micro-analysis test, which allows for complex peturbations, too conservative.

Prakash, OM, II↗
NASA NTRS2001

Enabling Advanced Automation in Spacecraft Operations with the Spacecraft Emergency Response System

True autonomy is the Holy Grail of spacecraft mission operations. The goal of launching a satellite and letting it manage itself throughout its useful life is a worthy one. With true autonomy, the cost of mission operations would be reduced to a negligible amount. Under full autonomy, any problems (no matter the severity or type) that may arise with the spacecraft would be handled without any human intervention via some combination of smart sensors, on-board intelligence, and/or smart automated ground system. Until the day that complete autonomy is practical and affordable to deploy, incremental steps of deploying ever-increasing levels of automation (computerization of once manual tasks) on the ground and on the spacecraft are gradually decreasing the cost of mission operations. For example, NASA's Goddard Space Flight Center (NASA-GSFC) has been flying spacecraft with low cost operations for several years. NASA-GSFC's SMEX (Small Explorer) and MIDEX (Middle Explorer) missions have effectively deployed significant amounts of automation to enable the missions to fly predominately in 'light-out' mode. Under light-out operations the ground system is run without human intervention. Various tools perform many of the tasks previously performed by the human operators. One of the major issues in reducing human staff in favor of automation is the perceived increased in risk of losing data, or even losing a spacecraft, because of anomalous conditions that may occur when there is no one in the control center. When things go wrong, missions deploying advanced automation need to be sure that anomalous conditions are detected and that key personal are notified in a timely manner so that on-call team members can react to those conditions. To ensure the health and safety of its lights-out missions, NASA-GSFC's Advanced Automation and Autonomy branch (Code 588) developed the Spacecraft Emergency Response System (SERS). The SERS is a Web-based collaborative environment that enables secure distributed fault and resource management. The SERS incorporates the use of intelligent agents, threaded discussions, workflow, database connectivity, and links to a variety of communications devices (e.g., two-way paging, PDA's, and Internet phones) via commercial gateways. When the SERS detects a problem, it notifies on-call team members, who then can remotely take any necessary actions to resolve the anomalies.The SERS goes well beyond a simple '911' system that sends out an error code to everyone with a pager. Instead, SERS' software agents send detailed data (i.e., notifications) to the most appropriate team members based on the type and severity of the anomaly and the skills of the on-call team members. The SERS also allows the team members to respond to the notifications from their wireless devices. This unique capability ensures rapid response since the team members no longer have to go to a PC or the control center for every anomalous event. Most importantly, the SERS enables safe experimentation with various techniques for increasing levels of automation, leading to robust autonomy. For the MIDEX missions at NASA GSFC, the SERS is used to provide 'human-in-the-loop' automation. During lights-out operations, as greater control is given to the MIDEX automated systems, the SERS can be configured to page remote personnel and keep them informed regarding actions taking place in the control center. Remote off-duty operators can even be given the option of enabling or inhibiting a specific automated response in near real time via their two-way pagers. The SERS facilitates insertion of new technology to increase automation, while maintaining the safety and security of mission resources. This paper will focus on SERS' overall functionality and how SERS has been designed to handle the monitoring and emergency response for missions with varying levels of automation. The paper will also convey some of the key lessons learned from SERS' deployment across of variety of missions, highlighting this incremental approach to achieving 'robust autonomy'.

Breed, Julie↗
NASA NTRS1995

High Pressure Earth Storable Rocket Technology Program: Basic Program

The HIPES Program was conducted for NASA-LeRC by TRW. The Basic Program consisted of system studies, design of testbed engine, fabrication and testing of engine. Studies of both pressure-fed and pump-fed systems were investigated for N2O4 and both MMH and N2H4 fuels with the result that N2H4 provides the maximum payload for all satellites over MMH. The higher pressure engine offers improved performance with smaller envelope and associated weight savings. Pump-fed systems offer maximum payload for large and medium weight satellites while pressure-fed systems offer maximum payload for small light weight satellites. The major benefits of HIPES are high performance within a confined length maximizing payload for lightsats which are length (volume) constrained. Three types of thrust chambers were evaluated -- Copper heatsink at 400, 500 and 600 psia chamber pressures for performance/thermal; water cooled to determine heat absorbed to predict rhenium engine operation; and rhenium to validate the concept. The HIPES engine demonstrated very high performance at 50 lbf thrust (epsilon = 150) and Pc = 500 psia with both fuels: Isp = 337 sec using N2O4-N2H4 and ISP = 327.5 sec using N2O4-MMH indicating combustion efficiencies greater than 98%. A powder metallurgy rhenium engine demonstrated operation with high performance at Pc = 500 psia which indicated the viability of the concept.

Chazen, M. L.↗
NASA NTRS1971

Analytic evaluation of display requirements for approach to landing

A computerized analysis procedure, based on a control theoretic model of the human pilot, is used to evaluate display requirements for longitudinal control in the landing approach. The display employed a digitally generated, perspective runway image with a superimposed artificial horizon for pitch indication. System performance measures are obtained for the approach phase of a light aircraft and a DC-8; predictions are made as to the effects of several display modifications. It is found that augmenting the basic display with glide slope reference bars and a velocity aim point yields adequate performance in calm air. Under moderate turbulence, the augmented display appears to be adequate for a DC-8 approach but not for a light aircraft.

Kleinman, D. L.↗
NASA NTRS1994

Development of a lightweight, light-trapped, thin GaAs solar cell for spacecraft applications

This paper describes ultra-lightweight, high performance, thin, light trapping GaAs solar cells for advanced space power systems. The device designs can achieve 24.5 percent efficiency at AMO and 1X conditions, corresponding to a power density of 330 W/m2. A significant breakthrough lies in the potential for a specific power of 2906 W/kg because the entire device is less than 1.5 microns thick. This represents a 440 percent improvement over conventional 4-mil silicon solar cells. In addition to being lightweight, this thin device design can result in increased radiation tolerance. The attachment of the cover glass support to the front surface has been demonstrated by both silicone and electrostatic bonding techniques. Device parameters of 1.002 volts open-circuit voltage, 80 percent fill factor, and a short-circuit current of 24.3 mA/sq cm have been obtained. This demonstrates a conversion efficiency of 14.4 percent resulting in a specific power of 2240 W/kg. Additionally, this new technology offers an alternative approach for enabling multi-bandgap solar cells and high output space solar power devices. The thin device structure can be applied to any 3-5 based solar cell application, yielding both an increase in specific power and radiation tolerance.

Hannon, Margaret H.↗
NASA NTRSDate not supplied

The Light Bender Concept for Power Distribution on a Lunar Base

Power generation and distribution is a challenge for a future lunar base. A promising concept for lunar power distribution is the light bender—a system that utilizes autonomously deployed mirrors to reflect sunlight to shaded regions on the lunar surface. The light bender system consists of two components: tandem reflector mirrors (TRM) which reflect sunlight to a permanently shaded region and the Cassegrain Fresnel distribution optics (CFDO) which collects the reflected light from the TRM and redirects light to local consumer nodes. This paper describes the light bender system concepts and the associated system analysis and technology development performed as part of a 2021 NASA Innovative Advanced Concepts (NIAC) phase I award.

Bradford Robertson↗
NASA NTRSDate not supplied

The Light Bender Concept for Power Distribution on a Lunar Base

Power generation and distribution is a challenge for a future lunar base. A promising concept for lunar power distribution is the light bender—a system that utilizes autonomously deployed mirrors to reflect sunlight to shaded regions on the lunar surface. The light bender system consists of two components: tandem reflector mirrors (TRM) which reflect sunlight to a permanently shaded region and the Cassegrain Fresnel distribution optics (CFDO) which collects the reflected light from the TRM and redirects light to local consumer nodes. This paper describes the light bender system concepts and the associated system analysis and technology development performed as part of a 2021 NASA Innovative Advanced Concepts (NIAC) phase I award.

Bradford Robertson↗
NASA NTRSDate not supplied

Developmental Hardware Testing Results and Forward Plans for the Spacecraft Water Impurity Monitor (SWIM) Organic Water Module (OWM)

We present testing results for developmental hardware of the Spacecraft Water Impurity Monitor (SWIM) Organic Water Module (OWM). SWIM-OWM will monitor spacecraft potable water and system water for trace organic contaminants. The system will detect and identify the specific organic chemical that makes up a given total organic carbon reading. We have built a first development unit (1DU) for SWIM-OWM, which directly injects aqueous water samples and detects chemicals with both a thermal conductivity detector and mass spectrometer sensor. The gas chromatography mass spectrometer (GCMS) system that comprises SWIM-OWM draws on the success of ISS-proven mass spectrometer hardware, and the demonstration of GCMS detection of trace organic contaminants in ISS cabin air. SWIM-OWM benefits from the excellent sensitivity and specificity afforded by GCMS. We have demonstrated detection of a set of chemicals relevant to both crew health and performance as well as system monitoring; these target chemicals range from light, volatile organics such as acetone and ethanol, to heavier, very non-volatile compounds such as dimethyl sulfone and o-phthalaldehyde. Direct aqueous injection was chosen for the general applicability of the technique to clean water sampling and to preclude sample pre-processing, which facilitates an on-line implementation of the SWIM-OWM when deployed in a spacecraft or habitation module. A specific advantage of direct aqueous injection when coupled with appropriate methods is that both the light, volatile organics and heavier non-volatiles can be detected from a single injection, in a single chromatogram. Results from 1DU testing will be discussed, and forward plans will be outlined for continued maturation of SWIM-OWM with the goal of implementing a technology demonstration for the purposes of maturing the engineering design and operations in an environment relevant to NASA’s future goals of exploring and setting up habitation on the Moon and Mars.

Water Monitoring↗
NASA NTRSDate not supplied

Developmental Hardware Testing Results and Forward Plans for Spacecraft Water Impurity Monitor (SWIM) Organic Water Module (OWM)

We present testing results for developmental hardware of the Spacecraft Water Impurity Monitor (SWIM) Organic Water Module (OWM). SWIM-OWM will monitor spacecraft potable water and system water for trace organic contaminants. The system will detect and identify the specific organic chemical that makes up a given total organic carbon reading. We have built a first development unit (1DU) for SWIM-OWM, which directly injects aqueous water samples and detects chemicals with both a thermal conductivity detector and mass spectrometer sensor. The gas chromatography mass spectrometer (GCMS) system that comprises SWIM-OWM draws on the success of ISS-proven mass spectrometer hardware, and the demonstration of GCMS detection of trace organic contaminants in ISS cabin air. SWIM-OWM benefits from the excellent sensitivity and specificity afforded by GCMS. We have demonstrated detection of a set of chemicals relevant to both crew health and performance as well as system monitoring; these target chemicals range from light, volatile organics such as acetone and ethanol, to heavier, very non-volatile compounds such as dimethyl sulfone and o-phthalaldehyde. Direct aqueous injection was chosen for the general applicability of the technique to clean water sampling and to preclude sample pre-processing, which facilitates an on-line implementation of the SWIM-OWM when deployed in a spacecraft or habitation module. A specific advantage of direct aqueous injection when coupled with appropriate methods is that both the light, volatile organics and heavier non-volatiles can be detected from a single injection, in a single chromatogram. Results from 1DU testing will be discussed, and forward plans will be outlined for continued maturation of SWIM-OWM with the goal of implementing a technology demonstration for the purposes of maturing the engineering design and operations in an environment relevant to NASA’s future goals of exploring and setting up habitation on the Moon and Mars.

Water Monitoring↗
NASA NTRS1998

Performance of the CELSS Antarctic Analog Project (CAAP) Crop Production System

Regenerative life support systems potentially offer a level of self-sufficiency and a concomitant decrease in logistics and associated costs in support of space exploration and habitation missions. Current state-of-the-art in plant based, regenerative life support requires resources in excess of resource allocations proposed for candidate mission scenarios. Feasibility thresholds have been identified for candidate exploration missions. The goal of this paper is to review recent advances in performance achieved in the CELSS Antarctic Analog Project (CAAP) in light of likely resource constraints. A prototype CAAP crop production chamber has been constructed and operated at the Ames Research Center. The chamber includes a number of unique hardware and software components focused on attempts to increase production efficiency, increase energy efficiency, and control the flow of energy and mass through the system to achieve enhanced performance efficiency. Both single crop, batch production, and continuous cultivation of mixed crops Product ion scenarios have been completed. The crop productivity as well as engineering performance of the chamber will be described. For each scenario, energy required and partitioned for lighting, cooling, pumps, fans, etc. is quantified. Crop production and the resulting lighting efficiency and energy conversion efficiencies are presented. In the mixed-crop scenario, with up to 25 different crops under cultivation, 17 sq m of crop area provided a mean of 515 g edible biomass per day (83% of the approximately 620 g required for one person). Lighting efficiency (moles on photons kWh-1) approached 4 and the conversion efficiency of light energy to biomass was greatly enhanced compared with conventional growing systems. Engineering and biological performance achieved place plant-based life support systems at the threshold of feasibility.

Bubenheim, David L.↗
NASA NTRS2015

Telerobotic Perception During Asteroid and Mars Regolith Operations Project

Current space telerobotic systems are constrained to only operating in bright light and dust-free conditions. This project will study the effects of difficult lighting and dust conditions on telerobotic perception systems to better assess and refine regolith operations on other neighboring celestial bodies. In partnership with Embry-Riddle Aeronautical University and Caterpillar, Inc., optical, LiDAR and RADAR sensing equipment will be used in performing the study. This project will create a known dust environment in the Swamp Works Granular Mechanics & Regolith Operations (GMRO) Laboratory regolith test bin to characterize the behavior of the sensing equipment in various calibrated lighting and dust conditions. It will also identify potential methods for mitigating the impacts of these undesirable conditions on the performance of the sensing equipment. Enhancing the capability of telerobotic perception systems will help improve life on earth for those working in dangerous, dusty mining conditions, as well as help advance the same technologies used for safer self-driving automobiles in various lighting and weather conditions. It will also prove to be a critical skill needed for advancing robotic and human exploration throughout our solar system, for activities such as mining on an asteroid or pioneering the first colony on Mars.

Technology Portfolio System↗
NASA NTRS1993

An optical processor for zero-crossing edge detection

An optical processor for zero-crossing edge detection is presented, which consists of two defocused imaging systems to perform the Gaussian convolutions and a VLSI, ferroelectric liquid crystal spatial light modulator (SLM) to determine the zero-crossings. The zero-crossing SLM is a 32 x 32 array of pixels located on 100 microns centers. Each pixels contains a phototransistor, an auto-scaling amplifier, a zero-crossing detection circuit, and a liquid crystal modulating pad. Electrical and optical characteristics of the zero-crossing SLM are presented along with experimental results of the system.

Jared, David A.↗
NASA NTRS2010

Effects of a Velocity-Vector Based Command Augmentation System and Synthetic Vision System Terrain Portrayal and Guidance Symbology Concepts on Single-Pilot Performance

This study investigated the effects of synthetic vision system (SVS) concepts and advanced flight controls on the performance of pilots flying a light, single-engine general aviation airplane. We evaluated the effects and interactions of two levels of terrain portrayal, guidance symbology, and flight control response type on pilot performance during the conduct of a relatively complex instrument approach procedure. The terrain and guidance presentations were evaluated as elements of an integrated primary flight display system. The approach procedure used in the study included a steeply descending, curved segment as might be encountered in emerging, required navigation performance (RNP) based procedures. Pilot performance measures consisted of flight technical performance, perceived workload, perceived situational awareness and subjective preference. The results revealed that an elevation based generic terrain portrayal significantly improved perceived situation awareness without adversely affecting flight technical performance or workload. Other factors (pilot instrument rating, control response type, and guidance symbology) were not found to significantly affect the performance measures.

Liu, Dahai↗
NASA NTRS1985

Advances in rechargeable lithium molybdenum disulfide batteries

The lithium molybdenum disulfide system as demonstrated in a C size cell, offers performance characteristics for applications where light weight and low volume are important. A gravimetric energy density of 90 watt hours per kilogram can be achieved in a C size cell package. The combination of charge retention capabilities, high energy density and a state of charge indicator in a rechargeable cell provides power package for a wide range of devices. The system overcomes the memory effect in Nicads where the full capacity of the battery cannot be utilized unless it was utilized on previous cycles. The development of cells with an advanced electrolyte formulation led to an improved rate capability especially at low temperatures and to a significantly improved life cycle.

Brandt, K.↗