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At least 325 records · Page 18

Microcalorimetric Measurements of Hydrogen Peroxide Stability

Recent interest in propellants with nontoxic reaction products has led to a resurgence of interest in hydrogen peroxide for various propellant applications. Because hydrogen peroxide is sensitive to contaminants and materials interactions, stability and shelf life are issues. A relatively new, ultrasensitive heat measurement technique, isothermal microcalorimetry, is being used at the White Sands Test Facility to monitor the decomposition of hydrogen peroxide at near ambient temperatures. Isothermal microcalorimetry measures the beat flow from a reaction vessel into a surrounding heat sink. In these applications, microcalorimetry is approximately 1,000 times more sensitive than accelerating rate calorimetry or differential scanning calorimetry for measuring thermal events. Experimental procedures have been developed for the microcalorimetric measurement of the ultra-small beat effects caused by incompatible interactions of hydrogen peroxide. The decomposition rates of hydrogen peroxide at the picomole/sec/gram level have been measured showing the effects of stabilizers and peroxide concentration. Typical measurements are carried out at 40 C over a 24-hour period, This paper describes a method for the conversion of the heat flow measurements to chemical reaction rates based on thermochemical considerations. The reaction rates are used in a study of the effects of stabilizer levels on the decomposition of propellant grade hydrogen peroxide.

Davis, Dennis D.↗

Low-Power Temperature-Swing Adsorption for Mars Atmosphere Acquisition

The promise of ISRU-based mission architectures for Mars surface exploration will begin to be realized during the next decade as robotic spacecraft sent to Mars carry components and whole chemical plants for producing propellants from the planet's atmosphere. These chemical plants will need to perform three primary operations: acquisition of atmospheric carbon dioxide, reactions to transform the gas into oxygen and possibly fuel, and storage of the products. This presentation focuses on development of technologies at NASA Ames Research Center for the first of these operations, carbon dioxide acquisition. The carbon dioxide acquisition component for a propellant production plant has several general, top level requirements. It has a stringent requirement for minimal power consumption; a critical need for long-term reliability over the period of time the chemical plant must operate (say, 500 days); a production rate requirement for carbon dioxide; and a state point requirement (particularly pressure) for the CO2 produced. The first two requirements help determine the best technological approach, while the latter two generally define the characteristics (e.g., size and power consumption) of the device. Mass and volume must be minimized, as usual.

Finn, J. E.↗

Characterization of the exhaust particulates in the ground cloud and high-altitude plume of large solid-propellant booster rockets

The report is concerned with the characterization of Al2O3 particles in the atmosphere. These particles comprise one of the major combustion products of the rocket propellant employed in the Space Shuttle boosters. A ground cloud and stratospheric plume are considered. It is concluded that the typical residence times in the atmosphere are much longer than earlier estimates have indicated.

Strand, L. D.↗

NASA Space Engineering Research Center for Utilization of Local Planetary Resources

In the processing of propellants, volatiles, and metals subject area, the following topics are discussed: reduction of lunar regolith; reduction of carbon dioxide; and reduction of carbonaceous materials. Other areas addressed include: (1) production of structural and refractory materials; (2) resource discovery and characterization; (3) system automation and optimization; and (4) database development. The majority of these topics are discussed with respect to the development of lunar and mars bases. Some main topics of interest include: asteroid resources, lunar resources, mars resources, materials processing, construction materials, propellant production, oxygen production, and space-based oxygen production plants.

Ramohalli, Kumar↗

Trash to Supply Gas (TtSG) Project Overview

Technologies that reduce logistical needs are a key to long term space missions. Currently, trash and waste generated during a mission is carried during the entire roundtrip mission or stored inside a logistic module which is de-orbited into Earth's atmosphere for destruction. The goal of the Trash to Supply Gas (TtSG) project is to develop space technology alternatives for converting trash and other waste materials from human spaceflight into high-value products that might include propellants or power system fuels in addition to life support oxygen and water. In addition to producing a useful product from waste, TtSG will decrease the volume needed to store waste on long term space missions. This paper presents an overview of the TtSG technologies and future plans for the project.

Hintze, Paul↗

The use of designed experiments in the process development of continuous propellant mixing

A continuous mix pilot plant was constructed at Aerojet Propulsion Division in Sacramento, California to develop a robust propellant mixing process for the full scale plant that was to be built at the NASA Advanced Solid Rocket Motor facility Yellow Creek, Mississippi. The plant was used to conduct dozens of subsystem and full system mixing tests for evaluation of equipment, processing methods, and control schemes for later use at the production plant. As a culmination to this work, a series of designed experiments were conducted using an eight run Taguchi analysis with four factors at two levels each to determine the primary effect of processing parameters on propellant ballistic and mechanical properties. The factors examined in these runs included the propellant production rate (454 (1000) and 622 kg/hr (1371 Ib/hr)), the product temperature out of the mixer (49 (120) and 63 deg C (145 deg F)), mixer screw speed (75 and 90 rpm), and the deaerator excess capacity (20 and 80 percent). Measured response variables included the uncured and cured density, Crawford Bomb liquid strand burning rates, and selected mechanical properties. The experiment revealed that several of the response variables displayed significant changes from run-to-run with the product temperature being the single most important factor. After concluding this experiment, a twenty-six hour confirmation run was conducted to verify the conclusions reached in the designed experiment. The extended run produced over 12,250 kgs (27,000 lbs) of propellant meeting all of the pre-run targeted properties including density (1.803 g/cc (0.065 lb/in(exp 3)) with a 0.12 percent coefficient of variation (CV) at 25 deg C (77 deg F)), liquid strand burn rate (0.889 cm/s (0.350 in/s) with a 0.69 percent CV at 4210 KPa (610 psig), 15.6 deg C (60 deg F)), nominal maximum stress (828 KPa (120 psig) with a 2.84 percent CV, S&E at 25 deg C (77 deg F), 5.08 cm/min (2 in/min)), strain at nominal maximum (47.4 percent with a 3.96 percent CV), and initial tangent modulus (5349 KPa (775 psig) with a 7.26 percent CV).

Campbell, J. A.↗

Space Resource Utilization and Extending Human Presence Across the Solar System

The Presidents Vision for Exploration is not a single mission, but an open ended journey that seeks to answer "How can we live on other worlds?" Using space resources is the only known approach for affordable, sustained, flexible, and self sufficient, human occupation beyond Earth orbit. Earth is a large planet. A simple analysis using the rocket equation shows that if Earth were a bit larger, chemical propulsion as a mechanism to access space would become impractical. Thus, even with the most efficient chemical rocket launch capability, the cost of lifting massive payloads into space will remain very steep (currently about $l00k/lb to the Moon and greater than $500k/lb to Mars). Space resource utilization should begin with an aggressive broad based demonstration program as afforded by the precursor missions implementation of the President's Vision of Exploration. Ion engine upper stages, for example, were studied for over 30 years, but only implemented in design after the Deep Space 1 in space demonstration. These demonstrations should include: extraction of elements from lunar regolith, and Martian soil and atmosphere, demonstration of power break even and growth from lunar or Mars moons derived photovoltaics, oxygen extraction for life support and propellant, and metals and alloys for in space repair and the production of habits and radiation shielding. Space resource utilization yields operational dividends through the subsequent programs including: propellant from lunar oxygen which could cut transportation costs from Earth in half, mega watts per year of power grown from lunar photovoltaics at decreasing cost per kW, decreased cost for human Mars missions by a factor of 10 by using propellant derived from Mars atmosphere for return, and in space manufacturing and food production with space resources yielding safe sustained and eventually self sufficient human presence in space. After the demonstration and implementation, the space resource utilization investment enables commercial and private viability beyond Earth orbit. For example, analysis has shown the lunar oxygen production for propellant becomes commercially viable after the exploration program completes the R&D, and power from lunar derived photovoltaics could, according to past NASA sponsored studies, pay for themselves while supplying most of Earth's electrical energy after about 17 years. Besides the Moon and Mars the resources of the near Earth asteroids enable the building of large space structures and science payloads. Analysis has shown that one of the thousands of these objects (some as easily accessible in space as the Moon and Mars), 2 km dia, the size of a typical open pit mine, would cost the total global financial product of Earth for 30,000 years if we were to launch it from Earth. Beyond Mars, the belt asteroids have been calculated to contain enough materials for habitat and life to support 10 quadrillion people. Thus, the development and use of space resources enables the extension of human life through the solar system allowing humanity to move from a planetary to a solar system society.

Curreri, Peter A.↗

Investigation of Effectiveness of Air-Heating a Hollow Steel Propeller for Protection Against Icing. 3: 25% Partitioned Blades

The icing protection obtained from an internally air-heated propeller blade partitioned to confine the heated air forward of 25-percent chord was investigated in the NACA Cleveland icing research tunnel. A production-model hollow steel propeller was modified with an Internal radial partition at 25-percent chord and with shank and tip openings to admit and exhaust the heated air. Temperatures were measured on the blade surfaces and in the heated-air system during tunnel icing conditions. Heat-exchanger effectiveness and photographs of Ice formations on the blades were obtained. Surface temperature measurements indicated that confining the heated air forward of the 25-percent chord gave.a more economical distribution of the applied heat as compared with unpartitioned and 50-percent partitioned blades, by dissipating a greater percentage of the available heat at the leading edge. At a propeller speed of 850 rpm, a heating rate of 7000 Btu per hour per blade at a shank air temperature of 400 F provided adequate Icing protection at ambient-air temperatures of 23 F but not at temperatures as low as 15 F. With the heating rate used, a heat-exchanger effectiveness of 77 percent was obtained as compared to 56 percent for 50-percent partitioned and 47 percent for unpartitioned blades.

Mulholland, Donald R.↗

Oxygen/Alcohol Dual Thrust RCS Engines

A non-toxic dual thrust RCS engine offers significant operational, safety, and performance advantages to the space shuttle and the next generation RLVs. In this concept, a single engine produces two thrust levels of 25 and 870 lbf. The low thrust level is provided by the spark torch igniter, which, with the addition of 2 extra valves, can also be made to function as a vernier. A dual thrust RCS engine allows 38 verniers to be packaged more efficiently on a vehicle. These 38 vemiers improve translation and reduce cross coupling, thereby providing more pure roll, pitch, and yaw maneuvers of the vehicle. Compared to the 6 vemiers currently on the shuttle, the 38 dual thrust engines would be 25 to 40% more efficient for the same maneuvers and attitude control. The vernier thrust level also reduces plume impingement and contamination concerns. Redundancy is also improved, thereby improving mission success reliability. Oxygen and ethanol are benign propellants which do not create explosive reaction products or contamination, as compared to hypergolic propellants. These characteristics make dual-thrust engines simpler to implement on a non-toxic reaction control system. Tests at WSTF in August 1999 demonstrated a dual-thrust concept that is successful with oxygen and ethanol. Over a variety of inlet pressures and mixture ratios at 22:1 area ratio, the engine produced between 230 and 297 sec Isp, and thrust levels from 8 lbf. to 50 lbf. This paper describes the benefits of dual-thrust engines and the recent results from tests at WSTF.

Angstadt, Tara↗

Investigation of Effectiveness of Air-Heating a Hollow Steel Propeller for Protection Against Icing. 2: 50% Impartitioned Blades

The icing protection afforded an internal air-heated propeller blade by radial partitioning at 50-percent chord to confine the heated air to the forward half of the blade was determined in the NACA Cleveland icing research tunnel. A modified production-model hollow steel propeller, was used for the investigation. Temperatures of the blade surfaces for several heating rates were measured under various tunnel Icing' conditions. Photographic observations of ice formations on blade surfaces and blade heat-exchanger effectiveness were obtained. With 50-percent partitioning of the blades, adequate icing protection at 1050 rpm was obtained with a heating rate of 26,000 Btu per hour per blade at the blade shank using an air temperature of 400 F with a flow rate of 280 pounds per hour per blade, which is one-third less heat than was found necessary for similar Ice protection with unpartitioned blades. The chordwise distribution of the applied heat, as determined by surface temperature measurements, was considered unsatisfactory with much of the heat dissipated well back of the leading edge. Heat-exchanger effectiveness of approximately 56 percent also Indicated poor utilization of available heat. This effectiveness was, however, 9 percent greater than that obtained from unpartitioned blades.

Perkins, Porter J.↗

Investigation of Effectiveness of Air-Heating a Hollow Steel Propeller for Protection Against Icing. 1: Unpartitioned Blades

An investigation to determine the effectiveness of icing protection afforded by air-heating hollow steel unpartitioned propeller blades has been conducted In the NACA Cleveland icing research tunnel. The propeller used was a production model modified with blade shank and tip openings to permit internal passage of heated air. Blade-surface and heated-air temperatures were obtained and photographic observations of Ice formations were made with variations In icing intensity and heating rate to the blades. For the conditions of Icing to which the propeller was subjected, it was found that adequate ice protection was afforded with a heating rate of 40 1 000 Btu per hour per blade. With less than 40,000 Btu per hour per blade, ice protection failed because of significant ice accretions on the leading edge. The chordwise distribution of heat was unsatisfactory with most of the available heat dissipated well back of the leading edge on both the thrust and camber face's instead of at the leading edge where it was most needed. A low utilization of available heat for icing protection is indicated by a beat-exchanger effectiveness of approximately 47 percent.

Mulholland, Donald R.↗

Catalytic Decomposition of Propellant Hydrazines, N-Nitrosodimethylamine, and N-Nitrodimethylamine

Remediation of propellant hydrazine spills, waste treatment, or cleanup of water contaminated with these propellants and/or their oxidation products is a subject of great concern for safety and the environment. Current remediation technologies typically employ oxidative methods, such as chlorination or ozonation. Methylated hydrazines, in particular 1,1-dimethythydrazine (UDMH) and to some degree monomethy1hydrazine (MMH), form N-Nitrosodimethylamine (NDMA) and N-Nitrodimethylamine (DMNM) during oxidation. These compounds are highly toxic and may persist if oxidative conditions are not sufficiently harsh. Since NDMA and DMNM may also be formed from exposure of MMH or UDMH to air, a need exists for a method that will remediate hydrazine, MMH, UDMH, NDMA, and DMNM. In this work, aqueous solutions of propellant hydrazines, NDMA, and DMNM were found to degrade by catalytic reduction with nickel-aluminum (Ni-Al) alloy under basic conditions. The reaction is based upon dissolution of At from Ni-Al alloy in aqueous media to form aluminum ion and hydrogen gas; and the resultant finely divided nickel catalyzes reduction of the hydrazine, nitrosoamine, or nitroamine by the hydrogen produced. Greater than 99 percent of hydrazine, MMH, UDMH, NDMA, and DMNM in aqueous solutions were degraded under laboratory conditions when reacted with Ni-Al alloy. UDMH was identified as an intermediate reduction product of NDMA and DNNM. NDMA and UDMH were identified as intermediate reduction products of DMNM. Control experiments without nickel showed no degradation of hydrazine, MMH or UDMH, while NDMA and DMNM were reduced to UDMH. Spill pillows containing Ni-Al alloy and solid sodium hydroxide were also found effective in absorption and degradation of UDMH. The application of chemical reduction as a means to propellant hydrazines, NDMA, and DMNM spill remediation, waste treatment, and water decontamination appears highly attractive.

Greene, Ben↗

Benefits of in situ propellant utilization for a Mars sample return mission

Previous Mars rover sample return mission studies have shown a requirement for Titan 4 or STS Space Shuttle launch vehicles to complete a sample return from a single Mars site. These studies have either used terrestrial propellants or considered in situ production of methane and oxygen for the return portion of the mission. Using in situ propellants for the return vehicles reduces the Earth launch mass and allows for a smaller Earth launch vehicle, since the return propellant is not carried from Earth. Carbon monoxide and oxygen (CO/O2) and methane and oxygen (CH4/O2) were investigated as in situ propellants for a Mars sample return mission and the results were compared to a baseline study performed by the Jet Propulsion Laboratory using terrestrial propellants. Capability for increased sample return mass, use of an alternate launch vehicle, and an additional mini-rover as payload were included. CO/O2 and CH4/O2 were found to decrease the baseline Earth launch mass by 13.6 and 9.2 percent, respectively. This resulted in higher payload mass margins for the baseline Atlas 2AS launch vehicle. CO/O2 had the highest mass margin. And because of this, it was not only possible to increase the sample return mass and carry an additional mini-rover, but was also possible to use the smaller Atlas 2A launch vehicle.

Wadel, Mary F.↗

Benefits of in situ propellant utilization for a Mars sample return mission

Previous Mars rover sample return mission studies have shown a requirement for Titan 4 or STS Space Shuttle launch vehicles to complete a sample return from a single Mars site. These studies have either used terrestrial propellants or considered in situ production of methane and oxygen for the return portion of the mission. Using in situ propellants for the return vehicles reduces the Earth launch mass and allows for a smaller Earth launch vehicle, since the return propellant is not carried from Earth. Carbon monoxide and oxygen (CO/O2) and methane and oxygen (CH4/O2) were investigated as in situ propellants for a Mars sample return mission and the results were compared to a baseline study performed by the Jet Propulsion Laboratory using terrestrial propellants. Capability for increased sample return mass, use of an alternate launch vehicle, and an additional mini-rover as payload were included. CO/O2 and CH4/O2 were found to decrease the baseline Earth launch mass by 13.6 and 9.2 percent, respectively. This resulted in higher payload mass margins for the baseline Atlas 2AS launch vehicle. CO/O2 had the highest mass margin. And because of this, it was not only possible to increase the sample return mass and carry an additional mini-rover, but was also possible to use the smaller Atlas 2A launch vehicle.

Wadel, Mary F.↗

Mars Ascent Vehicle-Propellant Aging

This project is to develop and test a new propellant formulation specifically for the Mars Ascent Vehicle (MAV) for the robotic Mars Sample Return mission. The project was initiated under the Planetary Sciences Division In-Space Propulsion Technology (ISPT) program and is continuing under the Mars Exploration Program. The two-stage, solid motor-based MAV has been the leading MAV solution for more than a decade. Additional studies show promise for alternative technologies including hybrid and bipropellant options, but the solid motor design has significant propellant density advantages well suited for physical constraints imposed while using the SkyCrane descent stage. The solid motor concept has lower specific impulse (Isp) than alternatives, but if the first stage and payload remain sufficiently small, the two-stage solid MAV represents a potential low risk approach to meet the mission needs. As the need date for the MAV slips, opportunities exist to advance technology with high on-ramp potential. The baseline propellant for the MAV is currently the carboxyl terminated polybutadiene (CTPB) based formulation TP-H-3062 due to its advantageous low temperature mechanical properties and flight heritage. However, the flight heritage is limited and outside the environments, the MAV must endure. The ISPT program competed a propellant formulation project with industry and selected ATK to develop a new propellant formulation specifically for the MAV application. Working with ATK, a large number of propellant formulations were assessed to either increase performance of a CTPB propellant or improve the low temperature mechanical properties of a hydroxyl terminated polybutadiene (HTPB) propellant. Both propellants demonstrated potential to increase performance over heritage options, but an HTPB propellant formulation, TP-H-3544, was selected for production and testing. The test plan includes propellant aging first at high vacuum conditions, representative of the Mars transit, followed by an additional year at simulated Mars surface conditions. The actual Mars surface environment is based on the igloo design, actively maintains the propellant at or above -40 degC, 95% carbon dioxide at Mars surface pressure. The NASA Marshall Space Flight Center (MSFC) Mars environment test facility is shown in figure 1 and located in the East Test area of Redstone Arsenal due to storage of live propellants. The facility consists of a vacuum chamber placed inside a large freezer unit. The facility includes pressure and temperature monitoring equipment in addition to a vacuum quality monitoring system spectrometer to record any outgassing products.

Dankanich, John↗

Lunar Polar In Situ Resource Utilization (ISRU) as a Stepping Stone for Human Exploration

A major emphasis of NASA is to extend and expand human exploration across the solar system. While specific destinations are still being discussed as to what comes first, it is imperative that NASA create new technologies and approaches that make space exploration affordable and sustainable. Critical to achieving affordable and sustainable exploration beyond low Earth orbit (LEO) are the development of technologies and approaches for advanced robotics, power, propulsion, habitats, life support, and especially, space resource utilization systems. Space resources and how to use them, often called In-Situ Resource Utilization (ISRU), can have a tremendous beneficial impact on robotic and human exploration of the Moon, Mars, Phobos, and Near Earth Objects (NEOs), while at the same time helping to solve terrestrial challenges and enabling commercial space activities. The search for lunar resources, demonstration of extraterrestrial mining, and the utilization of resource-derived products, especially from polar volatiles, can be a stepping stone for subsequent human exploration missions to other destinations of interest due to the proximity of the Moon, complimentary environments and resources, and the demonstration of critical technologies, processes, and operations. ISRU and the Moon: There are four main areas of development interest with respect to finding, obtaining, extracting, and using space resources: Prospecting for resources, Production of mission critical consumables like propellants and life support gases, Civil engineering and construction, and Energy production, storage, and transfer. The search for potential resources and the production of mission critical consumables are the primary focus of current NASA technology and system development activities since they provide the greatest initial reduction in mission mass, cost, and risk. Because of the proximity of the Moon, understanding lunar resources and developing, demonstrating, and implementing lunar ISRU provides a near and early opportunity to perform the following that are applicable to other human exploration mission destinations: Identify and characterize resources, how they are distributed, and the material, location and environment in which they are found; Demonstrate concepts, technologies, and hardware that can reduce the cost and risk of human exploration beyond Earth orbit; Use the Moon for operation experience and mission validation for much longer missions that are farther from Earth Develop and evolve ISRU to support sustained, economical human presence beyond Earth's orbit, including promoting space commercialization As Table 1 depicts, the Moon provides environments and resources applicable to Mars and NEOs. Two lunar ISRU resource and product pathways that have notable synergism with NEO, Phobos/Demos, and Mars ISRU are oxygen/metal extraction from regolith, and water/volatile extraction from lunar polar materials. To minimize the risk of developing and incorporating ISRU into human missions, a phased implementation plan is recommended that starts with prospecting and demonstrating critical technologies on robotic and human missions, then performing pilot scale operations (in non-mission critical roles) to enhance exploration mission capabilities, leading to full utilization of space resources in mission critical roles. Which lunar ISRU pathway is followed will depend on the results of early resource prospecting/proof-ofconcept mission(s), and long-term human exploration plans.

Sanders, Gerald B.↗

Development, Verification and Validation of Parallel, Scalable Volume of Fluid CFD Program for Propulsion Applications

There are many instances involving liquid/gas interfaces and their dynamics in the design of liquid engine powered rockets such as the Space Launch System (SLS). Some examples of these applications are: Propellant tank draining and slosh, subcritical condition injector analysis for gas generators, preburners and thrust chambers, water deluge mitigation for launch induced environments and even solid rocket motor liquid slag dynamics. Commercially available CFD programs simulating gas/liquid interfaces using the Volume of Fluid approach are currently limited in their parallel scalability. In 2010 for instance, an internal NASA/MSFC review of three commercial tools revealed that parallel scalability was seriously compromised at 8 cpus and no additional speedup was possible after 32 cpus. Other non-interface CFD applications at the time were demonstrating useful parallel scalability up to 4,096 processors or more. Based on this review, NASA/MSFC initiated an effort to implement a Volume of Fluid implementation within the unstructured mesh, pressure-based algorithm CFD program, Loci-STREAM. After verification was achieved by comparing results to the commercial CFD program CFD-Ace+, and validation by direct comparison with data, Loci-STREAM-VoF is now the production CFD tool for propellant slosh force and slosh damping rate simulations at NASA/MSFC. On these applications, good parallel scalability has been demonstrated for problems sizes of tens of millions of cells and thousands of cpu cores. Ongoing efforts are focused on the application of Loci-STREAM-VoF to predict the transient flow patterns of water on the SLS Mobile Launch Platform in order to support the phasing of water for launch environment mitigation so that vehicle determinantal effects are not realized.

West, Jeff↗

Experimental investigation of a throttlable 15 cm hollow cathode ion thruster

The use of dished high perveance grids on a 15 cm modified SERT 2 thruster is shown to facilitate throttled operation over a beam current range from 60 to 600 mA. Effects of increasing the radial component of the magnetic field in the main discharge chamber and decreasing the dimensions of the cathode discharge region are examined and found to degrade performance to the extent that primary electrons are forced in toward the center-line of the thruster. Studies of the baffle aperture region of two thrusters indicate that the electric potential gradient vector is perpendicular to the local magnetic field lines when the thruster is operating properly. The correlation between the shape of the ion beam current density and that of the ion density at the screen grid within the thruster is shown to be 94%. Additional experimental studies on maximum propellant utilization, plasma ion production cost, neutral density in the cathode discharge region, double ion production in hollow cathode thrusters and thermal flow meter performance are discussed.

Wilbur, P. J.↗