Effect of inert propellant injection on Mars ascent vehicle performance

A Mars ascent vehicle is limited in performance by the propellant which can be brought from Earth. In some cases the vehicle performance can be improved by injecting inert gas into the engine, if the inert gas is available as an in-situ resource and does not have to be brought from Earth. Carbon dioxide, nitrogen, and argon are constituents of the Martian atmosphere which could be separated by compressing the atmosphere, without any chemical processing step. The effect of inert gas injection on rocket engine performance was analyzed with a numerical combustion code that calculated chemical equilibrium for engines of varying combustion chamber pressure, expansion ratio, oxidizer/fuel ratio, and inert injection fraction. Results of this analysis were applied to several candidate missions to determine how the required mass of return propellant needed in low Earth orbit could be decreased using inert propellant injection

Full system engineering design and operation of an oxygen plant

The production of oxygen from the indigenous resources on Mars is described. After discussing briefly the project's background and the experimental system design, specific experimental results of the electrolytic cell are presented. At the heart of the oxygen production system is a tubular solid zirconia electrolyte cell that will electrochemically separate oxygen from a high-temperature stream of Coleman grade carbon dioxide. Experimental results are discussed and certain system efficiencies are defined. The parameters varied include (1) the cell operating temperature; (2) the carbon dioxide flow rate; and (3) the voltage applied across the cell. The results confirm our theoretical expectations

The synthesis and spectroscopic studies of titanium-amido complexes as potential catalysts for small molecule activation and polymerization reactions

The last decade has seen what some have termed a \u27renaissance\u27 in amido--transition metal chemistry. In part, this has been due to a better appreciation of the amido moiety (R₂N) as a ligand. Moreover, it has been due to the dramatic reactivity that amido complexes have been shown to display, especially when the complex is low coordinate and high valent. This dissertation describes the utilization of dihydrodibenzoazepinyl and carbazolyl ligands to effectively stabilize titanium complexes. These two ligand sets vary in their electron contribution to the metal center due to reduced [pi]-donation from the carbazolyl ligand, this in turn effects the structural properties of the system. These novel titanium--amido systems are potential catalysts for small molecule activation and polymerization reactions. Their synthesis and extensive characterization through X-ray and NMR spectroscopy techniques is described herein. The synthesis of chelating amine ligands for the stabilization of metal centers can afford fascinating molecules. These compounds are fundamentally interesting due to the orientation of the four nitrogen lone pairs that are within close proximity to one another. The synthesis, reactivity and analysis of 1,2,3,4,5,6,7,8--octahydro-2a,4a,6a,8a-tetraazacyclopenta[f,g]acenaphthylene is reported

Autonomous space processor for orbital debris

The development of an Autonomous Space Processor for Orbital Debris (ASPOD) was the goal. The nature of this craft, which will process, in situ, orbital debris using resources available in low Earth orbit (LEO) is explained. The serious problem of orbital debris is briefly described and the nature of the large debris population is outlined. The focus was on the development of a versatile robotic manipulator to augment an existing robotic arm, the incorporation of remote operation of the robotic arms, and the formulation of optimal (time and energy) trajectory planning algorithms for coordinated robotic arms. The mechanical design of the new arm is described in detail. The work envelope is explained showing the flexibility of the new design. Several telemetry communication systems are described which will enable the remote operation of the robotic arms. The trajectory planning algorithms are fully developed for both the time optimal and energy optimal problems. The time optimal problem is solved using phase plane techniques while the energy optimal problem is solved using dynamic programming

Production and use of metals and oxygen for lunar propulsion

Production, power, and propulsion technologies for using oxygen and metals derived from lunar resources are discussed. The production process is described, and several of the more developed processes are discussed. Power requirements for chemical, thermal, and electrical production methods are compared. The discussion includes potential impact of ongoing power technology programs on lunar production requirements. The performance potential of several possible metal fuels including aluminum, silicon, iron, and titanium are compared. Space propulsion technology in the area of metal/oxygen rocket engines is discussed

Proton Association Constants of His 37 in the Influenza-A M218–60 Dimer-of-Dimers

National Institute of Biomedical Imaging and Bioengineering (U.S.) (EB001960)National Institute of Biomedical Imaging and Bioengineering (U.S.) (EB002026)National Institute of Biomedical Imaging and Bioengineering (U.S.) (GM094648

Anhydrous ammonia application losses using single-disc and knife fertilizer injector

Anhydrous ammonia (NH3) is injected below the soil surface during application to limit loss to the atmosphere. Application at a shallower depth may reduce tractor power or allow greater speed, which could increase field capacity if NH3 losses are held to acceptable levels. Losses of NH3 during, and for 1 h after, field application were measured from a typical knife injector treatment operated at a 15-cm (6-in.) depth and 8-km/h (5-mph) travel speed and from a single-disc injector operated at shallower depths [5 and 10 cm (2 and 4 in.)] and a range of travel speeds [8, 12, and 16 km/h (5, 7.5, and 10 mph)]. NH3 losses during application as measured with a hood over the single-disc injector were 3% to 7% in clay loam, silty clay loam, and loam soils and 21% to 52% in a coarser-textured fine sandy loam soil. Applying with a knife injector at deeper depth resulted in losses of 1% to 2% across all soil types. NH3 losses measured during an hour after application with stationary collection over the injection trench were 1% or less for all treatments. Losses during application were 5 to 55 times greater than during the first hour after application

Reducing anhydrous ammonia application by optimizing distribution

Anhydrous ammonia is one of the most popular ways to fertilize U.S. crops. As it has risen in cost, farmers and researchers have been seeking more efficient ways to apply this nitrogen fertilizer

Field Evaluation of Anhydrous Ammonia Manifold Performance

Experiments conducted between August 1999 and April 2002 evaluated anhydrous ammonia manifold distribution during field application at 84- and 168-kg N/ha (75- and 150-lb N/acre) application rates. Multiple manifolds including the conventional (Continental NH3 Model 3497, Dallas, Tex.), Vertical-Dam (Continental NH3 Dallas, Tex.), RotaflowTM(H.I. Fraser Pty Ltd, Sydney, Australia), Equa-flowTM(PGI International, Houston, Tex.), FD-1200 prototype (CDS John Blue Co., Huntsville, Ala.), and the Impellicone prototype manifold were tested. Temperature and pressure data were collected along the flow path.Results showed high distribution variation by the conventional manifold at both application rates, with average coefficient of variation (CV) values in excess of 16%. At the 84-kg N/ha (75-lb N/acre) rate, all other manifolds tested had significantly lower application variation (. = 0.05). At the 168-kg N/ha (150-lb N/acre) rate, the conventional manifold grouped statistically with the Vertical-Dam with a corn ring and the FD-1200 prototype, producing CV values between 9.5% and 16.2%. All other manifolds had significantly lower application variation. The Impellicone, Rotaflow., and Equa-flow., manifolds performed with the lowest measured variation at both rates, yielding best performance at the 168-kg N/ha (150-lb N/acre) rate with CV in the 6% range.Analysis of recorded temperature and pressure data indicate that NH3 flowing through the system very closely follows the saturation line and acts as a saturated mixture. Predictions of NH3 quality based on calculations of an ideal adiabatic mixture are supported by this result. Investigation for correlation between CV, air temperature, and percent of volume in the vapor phase of NH3 resulted in only a visual trend that may suggest a reduction in CV with lower percent of volume in the vapor phase.Results suggest that replacement of a conventional manifold with a Vertical-Dam manifold or any of the other manifolds tested could reduce application variation between 7.0% and 16.5% at 84 kg N/ha (75 lb N/acre) and 1.0% and 10.2% at 168 kg N/ha (150 lb N/acre). This change could reduce application rate by eliminating the need for over-application to compensate for variations