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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 253 records · Page 14
All sourcesNASA NTRSDOE OSTI
NASA NTRS2016

Post-Test Inspection of NASA's Evolutionary Xenon Thruster Long-Duration Test Hardware: Discharge Chamber

The NEXT Long-Duration Test is part of a comprehensive thruster service life assessment intended to demonstrate overall throughput capability, validate service life models, quantify wear rates as a function of time and operating condition, and identify any unknown life-limiting mechanisms. The test was voluntarily terminated in February 2014 after demonstrating 51,184 hours of high-voltage operation, 918 kg of propellant throughput, and 35.5 MN-s of total impulse. The post-test inspection of the thruster hardware began shortly afterwards with a combination of non-destructive and destructive analysis techniques, and is presently nearing completion. This paper presents relevant results of the post-test inspection for the discharge chamber as well as other miscellaneous components such as the high-voltage propellant isolators and electrical cabling. Comparison of magnetic field measurements taken during pretest and post-test inspections indicate that the field strength did not degrade, consistent with performance data obtained during the test. Inspection of discharge chamber mesh samples show a deposition coating primarily composed of grid material that is approximately 15 micrometers in thickness. This thickness is well within the retention capability of the mesh and is therefore not expected to present any issues. Approximately 3.1 grams of deposition flakes were found at the bottom of the discharge chamber, composed primarily of grid material and carbon. Calculated size histograms of these flakes indicate that 99% have a maximum dimension of 200 micrometers or smaller, which is significantly less than the ion optics grid gap. Larger flakes that are capable of causing a grid-to-grid short will be analyzed to determine if their formation will occur in flight or is a facility effect. The high-voltage propellant isolators as well as numerous other electrical insulators were inspected and no evidence of arcing or any other issues were found.

Electric Propulsion↗
NASA NTRS2021

Post-test Inspection of NASA’s Evolutionary Xenon Thruster Long-Duration Test Hardware: Discharge Chamber

The NEXT Long-Duration Test is part of a comprehensive thruster service life assessment intended to demonstrate overall throughput capability, validate service life models, quantify wear rates as a function of time and operating condition, and identify any unknown life-limiting mechanisms. The test was voluntarily terminated in February 2014after demonstrating 51,184 hours of high-voltage operation, 918 kg of propellant throughput, and 35.5 MN-s of total impulse. The post-test inspection of the thruster hardware began shortly afterwards with a combination of non-destructive and destructive analysis techniques, and is presently nearing completion. This paper presents relevant results of the post-test inspection for the discharge chamber as well as other miscellaneous components such as the high-voltage propellant isolators and electrical cabling. Comparison of magnetic field measurements taken during pretest and post-test inspections indicate that the field strength did not degrade, consistent with performance data obtained during the test. Inspection of discharge chamber mesh samples show a deposition coating primarily composed of grid material that is approximately 15 μm in thickness. This thickness is well within the retention capability of the mesh and is therefore not expected to present any issues. Approximately 3.1 grams of deposition flakes were found at the bottom of the discharge chamber, composed primarily of grid material and carbon. Calculated size histograms of these flakes indicate that 99% have a maximum dimension of 200 μm or smaller, which is significantly less than the ion optics grid gap. Larger flakes that are capable of causing a grid-to-grid short will be analyzed to determine if their formation will occur in flight or is a facility effect. The high-voltage propellant isolators as well as numerous other electrical insulators were inspected and no evidence of arcing or any other issues were found.

Rohit Shastry↗
NASA NTRS2000

Autonomous Relative Navigation for Formation-Flying Satellites Using GPS

The Goddard Space Flight Center is currently developing advanced spacecraft systems to provide autonomous navigation and control of formation flyers. This paper discusses autonomous relative navigation performance for a formation of four eccentric, medium-altitude Earth-orbiting satellites using Global Positioning System (GPS) Standard Positioning Service (SPS) and "GPS-like " intersatellite measurements. The performance of several candidate relative navigation approaches is evaluated. These analyses indicate that an autonomous relative navigation position accuracy of 1meter root-mean-square can be achieved by differencing high-accuracy filtered solutions if only measurements from common GPS space vehicles are used in the independently estimated solutions.

Gramling, Cheryl↗
NASA NTRS1973

Simulator performance validation and improvement through recorded data.

During the development of two-segment approach procedures instrumentation systems were installed on a 727 flight simulator to monitor a variety of flight parameters. Parameters monitored and data format were designed to be the same as those to be used in later flight tests with line aircraft. Good correlation existed between simulator and aircraft data in many areas. Previously identified areas of poor simulation were checked with quantitative data. The objective data obtained could be used for simulation improvements in areas previously changed primarily by using subjective data obtained from pilots. Areas where similar techniques could improve simulation were identified.

Seay, D. L.↗
NASA NTRS1992

Human Factors Of Flight-Deck Checklists

Report analyzes functions, formats, designs, lengths, and usage of normal cockpit checklists, as well as limitations of aircraft personnel who must interact with them. Checklist problems discussed in report also found in other high-risk industries such as: marine, nuclear, and chemical-process industries, as well as, civilian and military air transportation.

Degani, Asaf↗
NASA NTRS2024

NASA's Human Research Program: Evolving Collaborations to Enable the Future of Human Spaceflight

Since its formation in 2007, the NASA Human Research Program’s (HRP) mission has been to protect the health and performance of astronauts as they explore beyond low Earth orbit. The HRP helps enable exploration spaceflight through a focused program of research that leads to the development and delivery of solutions to protect human health and performance during and after these missions. This research is conducted primarily in ground analogs of the spaceflight environment and on the International Space Station (ISS). Over the last 3 years, NASA has undergone transformative changes with the flight of Artemis I, the formation of the Commercial Low Earth Orbit Destinations Program, commercial flights to the ISS, and collaboration with new international partners participating in human spaceflight. The HRP has embraced these new opportunities and is collaborating on all these fronts to collect biomedical research data. Artemis I marked the arrival of NASA’s new human spaceflight exploration missions. NASA established the Moon to Mars Program Office to design a roadmap for the exploration of the lunar surface and the journey beyond to Mars. The HRP has a critical role in conducting research and delivering technologies that will lead to solutions that protect human health and performance, and is working closely with the Moon to Mars Office to ensure these deliverables are ready in time to support their strategy. The HRP is also developing the partnership strategies required to support these deliverables. Commercial space flights, both free flyer and suborbital missions and private astronaut missions to the ISS, are providing broader opportunities and more subjects to characterize spaceflight-induced changes to the human system and to test countermeasures. To better use these opportunities to achieve its mission, the HRP has been working to understand the commercial spaceflight companies’ needs and then partnering with them on aspects of mutual interest. In addition, the HRP continues to engage in long-standing relationships with its international partners through the International Space Life Sciences Working Group and other joint international groups. The HRP is interested in sharing its knowledge and collaborating on projects of mutual interest with new countries that are developing capabilities for human spaceflight. The next 10 years will shape how humanity partners on exploration missions to Mars, and the HRP is committed to enabling and developing collaborative strategies with commercial and international partners to keep humans safe and productive as they explore longer and further into space.

Human research↗
NASA NTRS2014

Ground Testing of the EMCS Seed Cassette for Biocompatibility with the Cellular Slime Mold, Dictyostelium Discoideum

The European Modular Cultivation System, EMCS, was developed by ESA for plant experiments. To expand the use of flight verified hardware for various model organisms, we performed ground experiments to determine whether ARC EMCS Seed Cassettes could be adapted for use with cellular slime mold for future space flight experiments. Dictyostelium is a cellular slime mold that can exist both as a single-celled independent organism and as a part of a multicellular colony which functions as a unit (pseudoplasmodium). Under certain stress conditions, individual amoebae will aggregate to form multicellular structures. Developmental pathways are very similar to those found in Eukaryotic organisms, making this a uniquely interesting organism for use in genetic studies. Dictyostelium has been used as a genetic model organism for prior space flight experiments. Due to the formation of spores that are resistant to unfavorable conditions such as desiccation, Dictyostelium is also a good candidate for use in the EMCS Seed Cassettes. The growth substratum in the cassettes is a gridded polyether sulfone (PES) membrane. A blotter beneath the PES membranes contains dried growth medium. The goals of this study were to (1) verify that Dictyostelium are capable of normal growth and development on PES membranes, (2) develop a method for dehydration of Dictyostelium spores with successful recovery and development after rehydration, and (3) successful mock rehydration experiments in cassettes. Our results show normal developmental progression in two strains of Dictyostelium discoideum on PES membranes with a bacterial food source. We have successfully performed a mock rehydration of spores with developmental progression from aggregation to slug formation, and production of morphologically normal spores within 9 days of rehydration. Our results indicate that experiments on the ISS using the slime mold, Dictyostelium discoideum could potentially be performed in the flight verified hardware of the EMCS ARC Seed Cassettes.

biocompatibility↗
NASA NTRS1986

Skeletal response to short-term weightlessness

Male Sprague Dawley rats were placed in orbit for 7 days aboard the space shuttle. Bone histomorphometry was performed in the long bones and lumbar vertebrae of flight rats and compared to data derived from ground based control rats. Trabecular bone mass was not altered during the first week of weightlessness. Strong trends were observed in flight rats for decreased periosteal bone formation in the tibial diaphysis, reduced osteoblast size in the proximal tibia, and decreased osteoblast surface and number in the lumbar vertebra. Histologic indices of bone resorption was relatively normal in flight rats. The results indicate that 7 day of weightlessness are not of sufficient duration to induce histologicaly detectable loss of trabecular bone in rats. However, cortical and trabecular bone formation appear to be diminished during the first week of space flight.

Wronski, T. J.↗
NASA NTRS1998

Spaceflight reduces somatic embryogenesis in orchardgrass (Poaceae)

Somatic embryos initiate and develop from single mesophyll cells in in vitro cultured leaf segments of orchard-grass (Dactylis glomerata L.). Segments were plated at time periods ranging from 21 to 0.9 d (21 h) prior to launch on an 11 d spaceflight (STS-64). Using a paired t-test, there was no significant difference in embryogenesis from preplating periods of 14 d and 21 d. However, embryogenesis was reduced by 70% in segments plated 21 h before launch and this treatment was significant at P=0.0001. The initial cell divisions leading to embryo formation would be taking place during flight in this treatment. A higher ratio of anticlinal:periclinal first cell divisions observed in the flight compared to the control tissue suggests that microgravity affects axis determination and embryo polarity at a very early stage. A similar reduction in zygotic embryogenesis would reduce seed formation and have important implications for long-term space flight or colonization where seeds would be needed either for direct consumption or to grow another generation of plants.

NASA Discipline Plant Biology↗
NASA NTRS2001

Preliminary Results of NASA's First Autonomous Formation Flying Experiment: Earth Observing-1 (EO-1)

NASA's first autonomous formation flying mission is completing a primary goal of demonstrating an advanced technology called enhanced formation flying. To enable this technology, the Guidance, Navigation, and Control center at the Goddard Space Flight Center has implemented an autonomous universal three-axis formation flying algorithm in executive flight code onboard the New Millennium Program's (NMP) Earth Observing-1 (EO-1) spacecraft. This paper describes the mathematical background of the autonomous formation flying algorithm and the onboard design and presents the preliminary validation results of this unique system. Results from functionality assessment and autonomous maneuver control are presented as comparisons between the onboard EO-1 operational autonomous control system called AutoCon(tm), its ground-based predecessor, and a stand-alone algorithm.

Folta, David↗
NASA NTRS2012

Lead-Free Experiment in a Space Environment

This Technical Memorandum addresses the Lead-Free Technology Experiment in Space Environment that flew as part of the seventh Materials International Space Station Experiment outside the International Space Station for approximately 18 months. Its intent was to provide data on the performance of lead-free electronics in an actual space environment. Its postflight condition is compared to the preflight condition as well as to the condition of an identical package operating in parallel in the laboratory. Some tin whisker growth was seen on a flight board but the whiskers were few and short. There were no solder joint failures, no tin pest formation, and no significant intermetallic compound formation or growth on either the flight or ground units.

Blanche, J. F.↗
NASA NTRS1993

In-flight near- and far-field acoustic data measured on the Propfan Test Assessment (PTA) testbed and with an adjacent aircraft

Flight tests to define the far-field tone source at cruise conditions were completed on the full-scale SR-7L advanced turboprop that was installed on the left wing of a Gulfstream 2 aircraft. This program, designated Propfan Test Assessment (PTA), involved aeroacoustic testing of the propeller over a range of test conditions. These measurements defined source levels for input into long-distance propagation models to predict en route noise. In-flight data were taken for seven test cases. Near-field acoustic data were taken on the Gulfstream fuselage and on a microphone boom that was mounted on the Gulfstream wing outboard of the propeller. Far-field acoustic data were taken by an acoustically instrumented Learjet that flew in formation with the Gulfstream. These flight tests were flown from El Paso, Texas, and from the NASA Lewis Research Center. A comprehensive listing of the aeroacoustic results from these flight tests which may be used for future analysis are presented.

Woodward, Richard P.↗
NASA NTRS2011

Flight Planning in the Cloud

This new interface will enable Principal Investigators (PIs), as well as UAVSAR (Uninhabited Aerial Vehicle Synthetic Aperture Radar) members to do their own flight planning and time estimation without having to request flight lines through the science coordinator. It uses an all-in-one Google Maps interface, a JPL hosted database, and PI flight requirements to design an airborne flight plan. The application will enable users to see their own flight plan being constructed interactively through a map interface, and then the flight planning software will generate all the files necessary for the flight. Afterward, the UAVSAR team can then complete the flight request, including calendaring and supplying requisite flight request files in the expected format for processing by NASA s airborne science program. Some of the main features of the interface include drawing flight lines on the map, nudging them, adding them to the current flight plan, and reordering them. The user can also search and select takeoff, landing, and intermediate airports. As the flight plan is constructed, all of its components are constantly being saved to the database, and the estimated flight times are updated. Another feature is the ability to import flight lines from previously saved flight plans. One of the main motivations was to make this Web application as simple and intuitive as possible, while also being dynamic and robust. This Web application can easily be extended to support other airborne instruments.

Flores, Sarah L.↗
NASA NTRS1980

An experimental evaluation of head-up display formats

Three types of head-up display format are investigated. Type 1 is an unreferenced (conventional) flight director, type 2 is a ground referenced flight path display, and type 3 is a ground referenced director. Formats are generated by computer and presented by reflecting collimation against a simulated forward view in flight. Pilots, holding commercial licenses, fly approaches in the instrument flight mode and in a combined instrument and visual flight mode. The approaches are in wind shear with varied conditions of visibility, offset, and turbulence. The displays are equivalent in pure tracking but there is a slight advantage for the unreferenced director in poor conditions. Flight path displays are better for tracking in the combined flight mode, possibly because of poor director control laws and the division of attention between superimposed fields. Workloads is better for the type 2 displays. The flight path and referenced director displays are criticized for effects of symbol motion and field limiting. In the subjective judgment of pilots familiar with the director displays, they are rated clearly better than path displays, with a preference for the unreferenced director. There is a fair division of attention between superimposed fields.

Naish, J. M.↗
NASA NTRS2015

The Magnetospheric Multiscale Constellation

The Magnetospheric Multiscale (MMS) mission is the fourth mission of the Solar Terrestrial Probe (STP) program of the National Aeronautics and Space Administration (NASA). The MMS mission was launched on March 12, 2015. The MMS mission consists of four identically instrumented spin-stabilized observatories which are flown in formation to perform the first definitive study of magnetic reconnection in space. The MMS mission was presented with numerous technical challenges, including the simultaneous construction and launch of four identical large spacecraft with 100 instruments total, stringent electromagnetic cleanliness requirements, closed-loop precision maneuvering and pointing of spinning flexible spacecraft, on-board GPS based orbit determination far above the GPS constellation, and a flight dynamics design that enables formation flying with separation distances as small as 10 km. This paper describes the overall mission design and presents an overview of the design, testing, and early on-orbit operation of the spacecraft systems and instrument suite.

Space mission design↗
NASA NTRS1999

Renal Stone Risk During Space Flight

Space flight produces a number of metabolic and physiological changes in the crewmembers exposed to microgravity. Following launch, body fluid volumes, electrolyte levels, and bone and muscle undergo changes as the human body adapts to the weightless environment. Changes in the urinary chemical composition may lead to the potentially serious consequences of renal stone formation. Previous data collected immediately after space flight indicate changes in the urine chemistry favoring an increased risk of calcium oxalate and uric acid stone formation (n = 323). During short term Shuttle space flights, the changes observed include increased urinary calcium and decreased urine volume, pH and citrate resulting in a greater risk for calcium oxalate and brushite stone formation (n = 6). Results from long duration Shuttle/Mir missions (n = 9) followed a similar trend and demonstrated decreased fluid intake and urine volume and increased urinary calcium resulting in a urinary environment saturated with the calcium stone-forming salts. The increased risk occurs rapidly upon exposure to microgravity, continues throughout the space flight and following landing. Dietary factors, especially fluid intake, or pharmacologic intervention can significantly influence the urinary chemical composition. Increasing fluid intake to produce a daily urine output of 2 liters/day may allow the excess salts in the urine to remain in solution, crystals formation will not occur and a renal stone will not develop. Results from long duration crewmembers (n = 2) who had urine volumes greater than 2.5 L/day minimized their risk of renal stone formation. Also, comparisons of stone-forming risk in short duration crewmembers clearly identified greater risk in those who produced less than 2 liters of urine/day. However, hydration and increased urine output does not correct the underlying calcium excretion due to bone loss and only treats the symptoms and not the cause of the increased urinary salts. Dietary modification and promising pharmacologic treatments may also be used to reduce the potential risk for renal stone formation. Potassium citrate is being used clinically to increase the urinary inhibitor levels to minimize the development of crystals and the growth of renal stones. Bisphosphonates are a class of drugs recently shown to help in patients with osteoporosis by inhibiting the loss of bones in elderly patients. This drug could potentially prevent the bone loss observed in astronauts and thereby minimize the increase in urinary calcium and reduce the risk for renal stone development. Results of NASA's renal stone risk assessment program clearly indicate that exposure to microgravity changes the urinary chemical environment such that there is an increased risk for supersaturation of stone-forming salts, including calcium oxalaie and brushite. These studies have indicated specific avenues for development of countermeasures for the increased renal stone risk observed during and following space flight. Increased hydration and implementation of pharmacologic countermeasures should largely mitigate the in-flight risk of renal stones.

Whitson, Peggy A.↗
NASA NTRS2008

Status of the AIAA Modeling and Simulation Format Standard

The current draft AIAA Standard for flight simulation models represents an on-going effort to improve the productivity of practitioners of the art of digital flight simulation (one of the original digital computer applications). This initial release provides the capability for the efficient representation and exchange of an aerodynamic model in full fidelity; the DAVE-ML format can be easily imported (with development of site-specific import tools) in an unambiguous way with automatic verification. An attractive feature of the standard is the ability to coexist with existing legacy software or tools. The draft Standard is currently limited in scope to static elements of dynamic flight simulations; however, these static elements represent the bulk of typical flight simulation mathematical models. It is already seeing application within U.S. and Australian government agencies in an effort to improve productivity and reduce model rehosting overhead. An existing tool allows import of DAVE-ML models into a popular simulation modeling and analysis tool, and other community-contributed tools and libraries can simplify the use of DAVE-ML compliant models at compile- or run-time of high-fidelity flight simulation.

Jackson, E. Bruce↗