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At least 1,189 records · Page 66

Iodine generator for reclaimed water purification

The system disclosed is for controlling the iodine level in a water supply in a spacecraft. It includes an iodine accumulator which stores crystalline iodine, an electrochemical valve to control the input of iodine to the drinking water and an iodine dispenser. A pump dispenses fluid through the iodine dispenser and an iodine sensor to a potable water tank storage. The iodine sensor electronically detects the iodine level in the water, and through electronic means, produces a correction current control. The correction current control operates the electro-chemical iodine valve to release iodine from the iodine accumulator into the iodine dispenser.

Wynveen, R. A.↗

The development of an air Brayton and a steam Rankine solar receiver

An air Brayton and a steam Rankine solar receiver now under development are described. These cavity receivers accept concentrated insolation from a single point focus, parabolic concentrator, and use this energy to heat the working fluid. Both receivers were designed for a solar input of 85 kw. The air Brayton receiver heats the air to 816 C. A metallic plate-fin heat transfer surface is used in this unit to effect the energy transfer. The steam Rankine receiver was designed as a once-through boiler with reheat. The receiver heats the water to 704 C to produce steam at 17.22 MPa in the boiler section. The reheat section operates at 1.2 MPA, reheating the steam to 704 C.

Greeven, M. V.↗

The fate of the hydroxyl radical in the earth's primitive atmosphere and implications for the production of molecular oxygen

Behavior of the hydroxyl radical produced by the photolysis of water vapor in the earth's early atmosphere is examined. Because of the substantial OH radical reactivity with trace species (CO, HCl, SO2, H2S, NH3, and CH4) the formation of molecular oxygen may be prevented, even at a trace species mixing ratio. The photolysis rate of H2O, with corrections for hydrogen exospheric escape, is capable of describing the oxidation of the atmosphere and crust but may not be used to determine the rate of molecular oxygen generation without consideration of the various OH-trace species reactions.

Vander Wood, T. B.↗

The photochemistry of the paleoatmosphere

Recent progress in the understanding of the chemistry and photochemistry of the paleoatmosphere is reviewed with emphasis on the application of photochemical models to the investigation of the evolution of the atmosphere. Photochemical calculations are presented which show that a primordial highly reducing atmosphere composed of methane and ammonia, if it formed at all, would be short-lived in the presence of solar ultraviolet radiation, giving way rapidly to a more mildly reducing atmosphere of carbon dioxide and nitrogen. Estimations of O2 produced from the photolysis of water vapor prior to the emergence of photosynthesis range from less than 10 to the -14th to 0.1 times the present atmospheric level, indicating the need for further research. A series of photochemical models of increasing complexity has been developed to study the evolution of atmospheric ozone taking into account reactions with O atoms, hydrogen oxides, nitrogen oxides, and chlorine as well as vertical transport, temperature and tropospheric chemistry so that the total content and vertical distribution of O3 may be determined for a specified level of paleoatmospheric O2.

Levine, J. S.↗

Extended atmospheres of outer planet satellites and comets

The cometary hydrogen particle-trajectory model was used successfully to analyze observations of Comet P/Encke. The Pioneer Venus Orbiter Ultraviolet Spectrometer observed the comet at 1216A (hydrogen Lyman-alpha) on 15 April 1984, when the comet was .58 AU from the Sun and 1.02 AU from Venus. The analysis implies a production rate at .58 AU of 3.3 x 10 to the 28th power/sec of the water molecules which photodissociate to produce the observed hydrogen.

Smyth, W. H.↗

Extended atmospheres of outer planet satellites and comets

The new cometary hydrogen particle-trajectory model, completed last year, has been used successfully to analyze observations of Comet P/Giacobini-Zinner. The Pioneer Venus Orbiter Ultraviolet Spectrometer observed the comet at 1216 A (hydrogen Lyman-a) on 11 September 1985 when the comet was 1.03 AU from the Sun and 1.09 AU from Venus. The analysis implies a production rate at 1.03 AU 2.3 x 10 to the 28th power/sec of the water molecules which photodissociate to produce the observed hydrogen. An upper limit for the H2O production rate of Comet P/Halley of 5 x 10 to the 28th power/sec at 2.60 AU was also obtained from the Pioneer Venus instrument.

Smyth, W. H.↗

CELSS and regenerative life support for manned missions to MARS

In the mid 1990's, the space station will become a point from which inter-planetary vehicles can be launched. The practicalities of a manned Mars mission are now being studied, along with some newer concepts for human life support. Specifically, the use of organisms such as plants and algae as the basis for life support systems is now being actively considered. A Controlled Ecological Life Support System (CELSS) is composed of several facilities: (1) to grow photosynthetic plants or algae which will produce food, oxygen and potable water, and remove carbon dioxide exhaled by a crew; (2) to process biomass into food; (3) to oxidize organic wastes into CO 2 ; and (4) to maintain system operation and stability. Such a system, when compared to using materials stored at launch, may have distinct weight and cost advantages, depending upon crew size and mission duration, as well as psychological benefits for the crew. The use of the system during transit, as well as in establishing a re-visitable surface camp, will increase the attractiveness of the CELSS concept for life support on interplanetary missions.

R D McElroy↗

The growth and harvesting of algae in a micro-gravity environment

Algae growth in a micro-gravity environment is an important factor in supporting man's permanent presence in space. Algae can be used to produce food, oxygen, and pure water in a manned space station. A space station is one example of a situation where a Controlled Ecological Life Support System (CELSS) is imperative. In setting up a CELSS with an engineering approach at the Aerospace department of the University of Colorado, questions concerning algae growth in micro-g have arisen. The Get Away Special (GAS) Fluids Management project is a means through which many questions about the effects of a micro-g environment on the adequacy of growth rates, the viability of micro-organisms, and separation of gases and solids for harvesting purposes can be answered. In order to be compatible with the GAS tests, the algae must satisfy the following criteria: (1) rapid growth rates, (2) sustain viability over long periods of non-growth storage, and (3) very brief latency from storage to rapid growth. Testing indicates that the overall growth characteristics of Anacystis Nidulans satisfy the specifications of GAS's design constraints. In addition, data acquisition and the method of growth instigation are two specific problems being examined, as they will be encountered in interfacing with the GAS project. Flight testing will be two-fold, measurement of algae growth in micro-g and separation of algae from growth medium in an artificial gravitation field. Post flight results will provide information on algae viability in a micro-g environment as reflected by algal growth rates in space. Other post flight results will provide a basis for evaluating techniques for harvesting algae. The results from the GAS project will greatly assist the continuing effort of developing the CELSS and its applications for space.

Wiltberger, Nancy L.↗

Monte Carlo particle-trajectory models for neutral cometary gases. I - Models and equations. II - The spatial morphology of the Lyman-alpha coma

The mathematical derivations of various methods employed in the Monte Carlo particle-trajectory model (MCPTM) are presented, and the application of the MCPTM to the calculation of the photochemical heating of the inner coma through the partial thermalization of cometary hydrogen atoms produced by the photodissociation of water is discussed. This model is then used to explain the observed morphology of the spatially extended Ly-alpha comas of comets. The rocket and Skylab images of the Ly-alpha coma of Comet Kohoutek are examined.

Combi, Michael R.↗

Space station propulsion test bed

A test bed was fabricated to demonstrate hydrogen/oxygen propulsion technology readiness for the intital operating configuration (IOC) space station application. The test bed propulsion module and computer control system were delivered in December 1985, but activation was delayed until mid-1986 while the propulsion system baseline for the station was reexamined. A new baseline was selected with hydrogen/oxygen thruster modules supplied with gas produced by electrolysis of waste water from the space shuttle and space station. As a result, an electrolysis module was designed, fabricated, and added to the test bed to provide an end-to-end simulation of the baseline system. Subsequent testing of the test bed propulsion and electrolysis modules provided an end-to-end demonstration of the complete space station propulsion system, including thruster hot firings using the oxygen and hydrogen generated from electrolysis of water. Complete autonomous control and operation of all test bed components by the microprocessor control system designed and delivered during the program was demonstrated. The technical readiness of the system is now firmly established.

Briley, G. L.↗

Spectroscopic study of combustion diagnostics on hydroxyl radicals

Experimental observations of propane-air flames were performed. Measurements of hydroxyl (OH) radical concentration were made using resonance line absorption techniques. A microwave-pumped low pressure discharge in argon and water vapor is employed to produce strong OH radical band radiation in the 308 nm region. This radiation is transmitted through the plume and absorption data are taken at various radical positions using an optical multichannel analyzer. This absorption data is used to compute OH number density using a model for the absorption band characteristics as a function of temperature based on an atlas of line strengths. A numerical computation of flow fields, temperature profile and OH number density is carried out by using a technique of computational fluid dynamics (CFD). The results of CFD computation are good compared with experimental observation with a good agreement.

Hung, R. J.↗

Characterization of the corrosion resistance of several alloys to dilute biologically active solutions

Sulfate reducing bacteria and acid producing bacteria/fungi detected in hygiene waters increased the corrosion rate in aluminum alloy. Biologically active media enhanced the formation of pits on metal coupons. Direct observation of gas evolved at the corrosion sample, coupled with scanning electron microscopy (SEM) and energy dispersive x-ray analysis of the corrosion products indicates that the corrosion rate is increased because the presence of bacteria favor the reduction of hydrogen as the cathodic reaction through the reaction of oxygen and water. SEM verifies the presence of microbes in a biofilm on the surface of corroding samples. The bacterial consortia are associated with anodic sites on the metal surface, aggressive pitting occurs adjacent to biofilms. Many pits are associated with triple points and inclusions in the aluminum alloy microstructure. Similar bacterial colonization was found on the stainless steel samples. Fourier transform Infrared Spectroscopy confirmed the presence of carbonyl groups in pitted areas of samples exposed to biologically active waters.

Walsh, Daniel W.↗

Holographic diagnostics of breakup phenomena of impinging jets for liquid rocket motor applications

The use of pulsed laser holography in analyzing the atomization of impinging jets is evaluated using a holographic camera system capable of recording a 3D image of the atomization process in 3 x 10 exp -8 seconds. The holocamera and the experimental configuration and procedure are described in detail. Two nozzles were fabricated to produce 1-mm diameter liquid water jets that impinged at 60 and 90 deg. Holograms were obtained for each nozzle at liquid velocities of 20 and 40 m/s. Analysis of the holograms revealed the evolution of the jets from the plane of emergence through the region of droplet formation. Features of interest included the growth of disturbances prior to the breakup region and the effect of these disturbances on the formation of ligaments and liquid globules. Preliminary analyses show that waves of atomized liquid formed after impingement are closely correlated to waves measured on the jets, leading to the possibility of controlling the atomization process at the nozzle.

Hess, C. F.↗

The onsite manufacture of propellant oxygen from lunar resources

The Aerojet carbothermal process for the manufacture of oxygen from lunar materials has three essential steps: the reduction of silicate with methane to form carbon monoxide and hydrogen; the reduction of carbon monoxide with hydrogen to form methane and water; and the electrolysis of water to form hydrogen and oxygen. The reactions and the overall process are shown. It is shown with laboratory experimentation that the carbothermal process is feasible. Natural silicates can be reduced with carbon or methane. The important products are carbon monoxide, metal, and slag. The carbon monoxide can be completely reduced to form methane and water. The water can be electrolyzed to produce hydrogen and oxygen. A preliminary engineering study shows that the operation of plants using this process for the manufacture of propellant oxygen has a large economic advantage when the cost of the plant and its operation is compared to the cost of delivering oxygen from Earth.

Rosenberg, Sanders D.↗

Ultraviolet spectroscopy of cometary comae

During the past decade, vacuum ultraviolet spectra of over 30 comets have been obtained with the IUE satellite observatory. With few exceptions, the spectra of these comets appear to be similar, with OH and H produced by the photodissociation of water being the dominant species and emissions of C, O, S, CS and CO2(+) usually present. Although signs of variabiity of many kinds in comet spectra appear, the evidence from the UV observations suggests that all comets have the same basic chemical composition and that observed differences are due to evolution and ageing processes. During the 1985-86 apparition of Comet Halley, spectra were also obtained by other spacecraft and by sounding rocket instruments, including a long-slit imaging spectrograph.

Feldman, Paul D.↗

Applications of squeezed states: Bogoliubov transformations and wavelets to the statistical mechanics of water and its bubbles

The squeezed states or Bogoliubov transformations and wavelets are applied to two problems in nonrelativistic statistical mechanics: the dielectric response of liquid water, epsilon(q-vector,w), and the bubble formation in water during insonnification. The wavelets are special phase-space windows which cover the domain and range of L(exp 1) intersection of L(exp 2) of classical causal, finite energy solutions. The multiresolution of discrete wavelets in phase space gives a decomposition into regions of time and scales of frequency thereby allowing the renormalization group to be applied to new systems in addition to the tired 'usual suspects' of the Ising models and lattice gasses. The Bogoliubov transformation: squeeze transformation is applied to the dipolaron collective mode in water and to the gas produced by the explosive cavitation process in bubble formation.

Defacio, Brian↗

Atomic Oxygen Removes Varnish And Lacquer From Old Paintings

Dry and relatively nondestructive plasma process found effective in removing protective coats from old paintings. Process generates monatomic oxygen, which reacts with varnish, lacquer, polyurethane, acrylic, and other organic coating materials; reactions produce mostly carbon monoxide and water vapor, then simply pumped away by vacuum system in which plasma generated. Does not attack oxide-based pigments in underlying paint layers, and brush-stroke marks remain undisturbed.

Rutledge, Sharon K.↗

Gas flow and fluidization in a thick dynamic regolith: A new mechanism for the formation of chondritic meteorites

We have previously shown that size and density sorting in a regolith which has been 'fluidized' by the passage or gases from the interior or the body can quantitatively explain metal-silicate fractionation, an important property of ordinary chondrites. Here we discuss whether the flow rates and flux or volatiles expected from a primitive parent body are likely to be sufficient for this mechanism. Many meteorite parent bodies may have contained volatiles. From a consideration of heat diffusion and fluid mechanics, we calculate the gas flow rate of volatiles (e.g., water) in the regolith of an asteroid-sized object heated by Al-26. Our calculations show that the flow velocities and flux of water vapor are sufficient to produce conditions suitable for fluidization. Other heat sources have yet to be considered, but literature work suggests that they may be equally effective.

Huang, Shaoxiong↗