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At least 127 records · Page 7

External Tank Aft Cargo Carrier

It has been found that the majority of the flights of the Space Transportation System (STS) are loaded above 90 percent volume capacity, while approximately 35 percent of the flights carry less than 50 percent of the lift capability (65,000 lb) of the current STS. This situation implies that the payload could be increased if the volume for the additional payload were available on the STS. The employment of the External Tank (ET) Aft Cargo Carrier (ACC) would provide the additional volume needed and, thus, enable the STS to use its residual capability. The current ACC configuration is an evolution of two years of study. The ACC is a general purpose payload carrier which can be adapted to specific large diameter payloads. The improvement of the STS capabilities by the ACC is discussed, and future applications are considered.

Mobley, T. B.↗

An Accelerated Development, Reduced Cost Approach to Lunar/Mars Exploration Using a Modular NTR-Based Space Transportation System

The results of integrated systems and mission studies are presented which quantify the benefits and rationale for developing a common, modular lunar/Mars space transportation system (STS) based on nuclear thermal rocket (NTR) technology. At present NASA's Exploration Program Office (ExPO) is considering chemical propulsion for an 'early return to the Moon' and NTR propulsion for the more demanding Mars missions to follow. The time and cost to develop these multiple systems are expected to be significant. The Nuclear Propulsion Office (NPO) has examined a variety of lunar and Mars missions and heavy lift launch vehicle (HLLV) options in an effort to determine a 'standardized' set of engine and stage components capable of satisfying a wide range of Space Exploration Initiative (SEI) missions. By using these components in a 'building block' fashion, a variety of single and multi-engine lunar and Mars vehicles can be configured. For NASA's 'First Lunar Outpost' (FLO) mission, an expendable NTR stage powered by two 50 klbf engines can deliver approximately 96 metric tons (t) to translunar injection (TLI) conditions for an initial mass in low earth orbit (IMLEO) of approximately 198 t compared to 250 t for a cryogenic chemical TLI stage. The NTR stage liquid hydrogen (LH2) tank has a 10 m diameter, 14.5 m length, and 66 t LH2 capacity. The NTR utilizes a UC-ZrC-graphite 'composite' fuel with a specific impulse (Isp) capability of approximately 900 s and an engine thrust-to-weight ratio of approximately 4.3. By extending the size and LH2 capacity of the lunar NTR stage to approximately 20 m and 96 t, respectively, a single launch Mars cargo vehicle capable of delivering approximately 50 t of surface payload is possible. Three 50 klbf NTR engines and the two standardized LH2 tank sizes developed for lunar and Mars cargo vehicle applications would be used to configure the Mars piloted vehicle for a mission as early as 2010. The paper describes the features of the 'common' NTR-based moon/Mars STS, examines performance sensitivities resulting from different 'mission mode' assumptions, and quantifies potential schedule and cost benefits resulting from this modular moon/Mars NTR vehicle approach.

Borowski, S.↗

Evaluation of Hanford Supernatant Waste Evaporation

Storage space within Hanford’s double shell tanks is running low, with only an approximate 4.1 Mgal of space remaining. Construction of additional storage space is not a pursuable option, but treatment of the waste via vacuum evaporation may be used to reduce the waste volume and increase the available amount of free space. However, without proper care and consideration, concentrating the waste may lead to harmful effects such as excessive solids generation, growth in liquid density and ionic concentration, and development of aggressive properties in the solution. OLI Studio was used to simulate a subset of DSTs using BBI ionic concentrations to generate recipes of every tank’s supernatant layer. Vacuum evaporation was performed by taking each simulated solution and bringing it to 50°C under a pressure of 60 Torr, after which the vapor phase was removed from the simulation, and the solution was brought back to ambient temperature and pressure. Several million gallons of space were created, and only about 100-200 kgal of solids were precipitated during evaporation. Minimal changes to the solution’s pitting factor occurred, and no solution is expected to develop aggressive characteristics due to evaporation. Although a theoretical result is provided, it is unique to the specific temperature and pressure value chosen for the simulation, and future transfers of waste are expected to cause changes in waste properties, which would cause the OLI recipes to lose accuracy. Though the results are not anticipated to be used as a target value or a guide, as an exercise, they show that the extent of volume gains could be equivalent to the construction of new DSTs.

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗

Solar energy meets 50 pecent of motel hot water needs--Key West, Florida

Final report describes domestic water preheat installed in 148 room motel. Equipment meets 50 percent of needs when motel is 100 percent occupied; equivalently, it supplies 100 percent of hot water when occupancy is 50 percent. System consists of 1,400 square feet of flat plate liquid solar collectors, storage tanks, pump, controller, and hardware.

Source record↗

Solar hot water system installed at Day's Inn Motel, Savannah, Georgia

The Solar System was designed to provide 50 percent of the total Domestic Hot Water (DHW) demand. Liquid Flat Plate Collectors (900 square feet) are used for the collector subsystem. The collector subsystem is closed loop, using 50 percent Ethylene Glycol solution antifreeze for freeze protection. The 1,000 gallon fiber glass storage tank contains two heat exchangers. One of the heat exchangers heats the storage tank with the collector solar energy. The other heat exchanger preheats the cold supply water as it passes through on the way to the Domestic Hot Water (DHW) tank heaters. Electrical energy supplements the solar energy for the DHW. The Collector Mounting System utilizes guy wires to structurally tie the collector array to the building.

Source record↗

Fast Track Lunar NTR Systems Assessment for NASA's First Lunar Outpost and Its Evolvability to Mars

Integrated systems and missions studies are presented for an evolutionary lunar-to-Mars space transportation system (STS) based on nuclear thermal rocket (NTR) technology. A 'standardized' set of engine and stage components are identified and used in a 'building block' fashion to configure a variety of piloted and cargo, lunar and Mars vehicles. The reference NTR characteristics include a thrust of 50 thousand pounds force (klbf), specific impulse (I(sub sp)) of 900 seconds, and an engine thrust-to-weight ratio of 4. 3. For the National Aeronautics and Space Administrations (NASA) First Lunar Outpost (FLO) mission, and expendable NTR stage powered by two such engines can deliver approximately 96 metric tonnes (t) to trans-lunar injection (TLI) conditions for an initial mass in low Earth orbit (IMLEO) of approximately 198 t compared to 250 t for a cryogenic chemical system. The stage liquid hydrogen (LH2) tank has a diameter, length, and capacity of 10 m, 14.5 m and 66 t, respectively. By extending the stage length and LH2 capacity to approximately 20 m and 96 t, a single launch Mars cargo vehicle could deliver to an elliptical Mars parking orbit a 63 t Mars excursion vehicle (MEV) with a 45 t surface payload. Three 50 klbf engines and the two standardized LH2 tanks developed for the lunar and Mars cargo vehicles are used to configure the vehicles supporting piloted Mars missions as early as 2010. The 'modular' NTR vehicle approach forms the basis for an efficient STS able to handle the needs of a wide spectrum of lunar and Mars missions.

Borowski, Stanley K.↗

Operation of an ADR Using Helium Exchange Gas as a Substitute for a Failed Heat Switch

The Soft X-ray Spectrometer (SXS) is one of four instruments on the Japanese Astro-H mission, which is currently planned for launch in late 2015. The SXS will perform imaging spectroscopy in the soft X-ray band (0.3-12 keV) using a 6 6 pixel array of microcalorimeters cooled to 50 mK. The detectors are cooled by a 3-stage adiabatic demagnetization refrigerator (ADR) that rejects heat to either a superfluid helium tank (at 1.2 K) or to a 4.5 K Joule-Thomson (JT) cryocooler. Four gas-gap heat switches are used in the assembly to manage heat flow between the ADR stages and the heat sinks. The engineering model (EM) ADR was assembled and performance tested at NASA/GSFC in November 2011, and subsequently installed in the EM dewar at Sumitomo Heavy Industries, Japan. During the first cooldown in July 2012, a failure of the heat switch that linked the two colder stages of the ADR to the helium tank was observed. Operation of the ADR requires some mechanism for thermally linking the salt pills to the heat sink, and then thermally isolating them. With the failed heat switch unable to perform this function, an alternate plan was devised which used carefully controlled amounts of exchange gas in the dewar's guard vacuum to facilitate heat exchange. The process was successfully demonstrated in November 2012, allowing the ADR to cool the detectors to 50 mK for hold times in excess of 10 h. This paper describes the exchange-gas-assisted recycling process, and the strategies used to avoid helium contamination of the detectors at low temperature.

Adiabatic demagnetization↗

Cryogenically formed prestressed composite fiber-metal structures for O2/N2 high pressure gas tanks.

Demonstration of high-structural-performance ARDEFORM cryoformed 301 stainless-steel glass-fiber-reinforced (GFR) vessels by room temperature tests of 13 1/2-in. diam spheres. Tests verified that the structural performance of ARDEFORM spherical GFR vessels not only exceeded that of all metal construction, but also bettered previous GFR experimental results by 50%. Achievement of essentially the full strength of fiberglass in a spherical wrap pattern was again verified. Significant weight advantages for this construction are projected for O2/N2 high-pressure gas tanks for Space Shuttle environmental control/life support system missions.

Gleich, D.↗

Investigation of the Damping of Liquids in Right-Circular Cylindrical Tanks, Including the Effects of a Time-Variant Liquid Depth

An experimental investigation was conducted to determine the effects of several basic variables upon the damping of the fundamental antisymmetric mode of liquids in right-circular cylindrical tanks without baffles. The variables examined include liquid depth, efflux rate, liquid amplitude, kinematic viscosity, and tank size. The data are presented in dimensionless form and compared with available theory. For the range of variables examined, variations of efflux rate and liquid amplitude were found to have no significant effects on the liquid damping. The following theoretical relationship was found to be adequate for the prediction of the variation of damping with liquid depth, kinematic viscosity, and tank size: [for equation see full text] where v is the kinematic viscosity, R is the cylinder radius, g is the acceleration due to gravity, and h is the liquid depth. However, the constant K was experimentally found in this investigation to have the value 5.23, which is 50 percent higher than the theoretically predicted value.

TANK↗

Three-Phase LCC-LCC Compensated 50-kW Wireless Charging System with Non-Zero Interphase Coupling

In this paper, an LCC-LCC compensated 50 kW 3phase (3φ) wireless charging system with nonzero interphase mutual inductance is demonstrated. The 3φ-LCC compensation is designed considering a nonzero mutual-inductance among the phase-coils to meet resonance criteria, balance voltages and currents of the resonant tank components, achieve desired voltage gain, and ensure the zero-voltage switching (ZVS) operation. An experimental prototype of the 3φ-LCC-LCC compensation circuit is built for a 50 kW bipolar coil-based 3φ wireless charging system. The prototype system was tested at rated 50 kW power for evaluating the efficiency, ZVS operation, electric and magnetic field emissions, and thermal characteristics. The experimental results show 94.3% dc-to-dc efficiency and only 4.4 μT rms magnetic field emission at the rated 50 kW output power.

Mohammad, Mostak↗

Clostridium autoethanogenum alters cofactor synthesis, redox metabolism, and lysine-acetylation in response to elevated H 2 :CO feedstock ratios for enhancing carbon capture efficiency

Clostridium autoethanogenum is an acetogenic bacterium that autotrophically converts carbon monoxide (CO) and carbon dioxide (CO 2 ) gases into bioproducts and fuels via the Wood–Ljungdahl pathway (WLP). To facilitate overall carbon capture efficiency, the reaction stoichiometry requires supplementation of hydrogen at an increased ratio of H 2 :CO to maximize CO 2 utilization; however, the molecular details and thus the ability to understand the mechanism of this supplementation are largely unknown. In order to elucidate the microbial physiology and fermentation where at least 75% of the carbon in ethanol comes from CO 2 , we established controlled chemostats that facilitated a novel and high (11:1) H 2 :CO uptake ratio. We compared and contrasted proteomic and metabolomics profiles to replicate continuous stirred tank reactors (CSTRs) at the same growth rate from a lower (5:1) H 2 :CO condition where ~ 50% of the carbon in ethanol is derived from CO 2 . Our hypothesis was that major changes would be observed in the hydrogenases and/or redox-related proteins and the WLP to compensate for the elevated hydrogen feed gas. Our analyses did reveal protein abundance differences between the two conditions largely related to reduction–oxidation (redox) pathways and cofactor biosynthesis, but the changes were more minor than we would have expected. While the Wood–Ljungdahl pathway proteins remained consistent across the conditions, other post-translational regulatory processes, such as lysine-acetylation, were observed and appeared to be more important for fine-tuning this carbon metabolism pathway. Metabolomic analyses showed that the increase in H 2 :CO ratio drives the organism to higher carbon dioxide utilization resulting in lower carbon storages and accumulated fatty acid metabolite levels. This research delves into the intricate dynamics of carbon fixation in C. autoethanogenum, examining the influence of highly elevated H 2 :CO ratios on metabolic processes and product outcomes. The study underscores the significance of optimizing gas feed composition for enhanced industrial efficiency, shedding light on potential mechanisms, such as post-translational modifications (PTMs), to fine-tune enzymatic activities and improve desired product yields.

09 BIOMASS FUELS↗

Refinement of Pitting Factor Basis to Evaluate Minimum Nitrite Requirement in Dilute Waste Chemistries

Considering that chloride concentrations are an order of magnitude lower at SRS than the maximum chloride previously tested to evaluate pitting susceptibility of carbon steel, it has been proposed that the Pitting Factor methodology be refined to determine if a reduction in the minimum nitrite requirement is warranted in more dilute solutions and those with chloride concentrations more indicative of waste tank chemistries at SRS. Through the use of cyclic potentiodynamic polarization, the susceptibility of A537 carbon steel to pitting corrosion was evaluated. The Pitting Factor was shown to accurately predict pitting susceptibility throughout the chemistry envelope evaluated. In addition, it was shown that nitrite is not required for inhibition of pitting corrosion in tank conditions with chloride concentrations observed at SRS and up to 4 M nitrate. Based upon these findings, new control limits were proposed that removed the minimum nitrite requirement within the chemistry envelope evaluated up to 50 °C.

36 MATERIALS SCIENCE↗

Challenging Pneumatic Requirements for Acoustic Testing of the Cryogenic Second Stage for the New Delta 3 Rocket

The paper describes the unique pneumatic test requirements for the acoustic and shock separation testing of the Second Stage for the new Delta III Rocket at the Goddard Space Flight Center in Greenbelt, Maryland. The testing was conducted in the 45,000 cu ft (25-feet wide by 30-feet deep by 50-foot high) Acoustic Facility. The acoustic testing required that the liquid oxygen (LOX) and liquid hydrogen (LH2) tanks be filled with enough liquid nitrogen (LN2) to simulate launch fuel masses during testing. The challenge for this test dealt with designing, procuring, and fabricating the pneumatic supply systems for quick assembly while maintaining the purity requirements and minimizing costs. The pneumatic systems were designed to fill and drain the both LOX and LH2 tanks as well as to operate the fill/drain and vent valves for each of the tanks. The test criteria for the pneumatic sub-systems consisted of function, cleanliness, availability, and cost. The first criteria, function, required the tanks to be filled and drained in an efficient manner while preventing them from seeing pressures greater than 9 psig which would add a pressure cycle to the tank. An LN2 tanker, borrowed from another NASA facility, served as the pre-cool and drain tanker. Pre-cooling the tanks allowed for more efficient and cost effective transfer from the LN2 delivery tankers. Helium gas, supplied from a high purity tube trailer, was used to pressurize the vapor space above the LN2 pushing it into the drain tanker. The tube trailer also supplied high pressure helium to the vehicle for valve control and component purges. Cleanliness was maintained by proper component selection, end-use particle filtration, and any on-site cleaning determined necessary by testing. In order to meet the availability/cost juggling act, products designed for LOX delivery systems were procured to ensure system compatibility while off the shelf valves and tubing designed for the semiconductor industry were procured for the gas systems.

Webb, Andrew T.↗

Melt-Spun PAN Precursor for Cost-Effective Carbon Fibers in High Pressure Compressed Gas Tankage

The objective of this program was to synthesize melt-spinnable polyacrylonitrile (PAN) precursor that will lead to carbon fiber 25% less expensive than carbon fiber produced from conventional PAN precursor when produced in large volumes. The carbon fiber produced from this precursor needs to achieve ≥ 700 ksi tensile strength with this cost reduction to replace the incumbent fiber. In this program, the technology for producing precursor and then converted carbon fiber (CF) capable of meeting the 700 ksi target was to be demonstrated at a small scale in tows, containing ≥ 100 filaments. If this program moved on to a “Phase 2”, the processes would be scaled up to produce and test Type IV compressed gas storage tanks capable of meeting the 700-bar ultimate targeted FOA performance level. Precursor fiber production typically contributes a large fraction (~50%) to finished CF manufactured cost. Presently, all high strength CFs are manufactured from solution spun PAN precursor, accomplished at low temperatures using large amounts of environmentally unfriendly solvents that impart major impact to line speed and costs involved with handling and reclaiming the solvents and associated “waste streams” required in spinning and extracting those solvents. PAN melt spinning was demonstrated by the company BASF in CF precursor production and used in production of some other acrylic fibers, but significant production challenges remain for meeting the established CF metrics. Melt spinning requires use of plasticizers to suppress the melt temperature of the predominantly PAN formulation to a point sufficiently below the temperature of significant cross-linking. Fortunately, BASF and this team’s earlier work had demonstrated acrylic formulations melt spun with combinations of plasticizing solvents at much lower solvent levels. This project team made significant progress in understanding technical issues and identifying formulation pathways in earlier work in this area where >250ksi strength was achieved. The goal of this program was to pursue a more comprehensive approach with a larger, more diverse team having greater equipment design and overall production capabilities to push rapidly beyond the science to resolve remaining “engineering” issues associated with establishing stable, continuous processes for precursor fiber leading to enhanced, cost-effective CF and composite tank production.

36 MATERIALS SCIENCE↗

Data report for tests on the heat transfer effects of the 0.0175 scale Rockwell International Space Shuttle Vehicle model 22-OT in the AEDC 50 inch B wind tunnel (0H4B), volume 1

Results of wind tunnel heat transfer tests of 0.0175-scale Rockwell International Space Shuttle Vehicle configurations for orbiter alone, tank alone, and orbiter plus external tank are presented. Body flap shielding of SSME's during simulated entry was investigated. The tests were conducted at Mach 8 for thirteen Reynolds number.

Foster, T. F.↗

Data report for tests on the heat transfer effects of the 0.0175-scale Rockwell International Space Shuttle Vehicle model 22-OT in the AEDC 50-inch B wind tunnel (OH4B), volume 3

Results of wind tunnel heat transfer tests of 0.0175-scale Rockwell International Space Shuttle Vehicle configurations for orbiter alone, tank alone, and orbiter plus external tank are presented. Body flap shielding of SSME's during simulated entry was also investigated. The tests were conducted at Mach 8 for thirteen Reynolds number per foot values ranging from 0.5 million to 3.72 million.

Foster, T. F.↗

Experimental solar heating-cooling system model tests of a full-scale building system

An experimental solar heating and cooling system model has been built and operated, combining elements that are programmable - heating and/or cooling load of a building, collected solar energy - with experimental equipment. The system model was based on the loads and components used in the Solar Building Test Facility (SBTF) which includes a 1394 square meter solar collector field, at NASA-Langley. Operations covered 5 continuous days under summer conditions. For the system model, up to 55% of the simulated collected solar energy was used for the building load. This amount constituted 35% of the building cooling load. Heat loss was significant. If tank heat loss were eliminated, 75% of the collected solar energy would be used. This amount would supply approximately 50% of the building cooling load.

Namkoong, D.↗

Status of Propulsion Technology Development Under the NASA In-Space Propulsion Technology Program

Since 2001, the In-Space Propulsion Technology (ISPT) program has been developing and delivering in-space propulsion technologies for NASA's Science Mission Directorate (SMD). These in-space propulsion technologies are applicable, and potentially enabling for future NASA Discovery, New Frontiers, Flagship and sample return missions currently under consideration. The ISPT program is currently developing technology in three areas that include Propulsion System Technologies, Entry Vehicle Technologies, and Systems/Mission Analysis. ISPT's propulsion technologies include: 1) the 0.6-7 kW NASA's Evolutionary Xenon Thruster (NEXT) gridded ion propulsion system; 2) a 0.3-3.9kW Halleffect electric propulsion (HEP) system for low cost and sample return missions; 3) the Xenon Flow Control Module (XFCM); 4) ultra-lightweight propellant tank technologies (ULTT); and 5) propulsion technologies for a Mars Ascent Vehicle (MAV). The NEXT Long Duration Test (LDT) recently exceeded 50,000 hours of operation and 900 kg throughput, corresponding to 34.8 MN-s of total impulse delivered. The HEP system is composed of the High Voltage Hall Accelerator (HIVHAC) thruster, a power processing unit (PPU), and the XFCM. NEXT and the HIVHAC are throttle-able electric propulsion systems for planetary science missions. The XFCM and ULTT are two component technologies which being developed with nearer-term flight infusion in mind. Several of the ISPT technologies are related to sample return missions needs: MAV propulsion and electric propulsion. And finally, one focus of the Systems/Mission Analysis area is developing tools that aid the application or operation of these technologies on wide variety of mission concepts. This paper provides a brief overview of the ISPT program, describing the development status and technology infusion readiness.

systems analysis↗