Search

Performing orbital insertion around Mars using aerocapture instead of a propulsive orbit insertion maneuver allows the saving of resources and/or the increase of the payload mass fraction. Aerocapture has never been employed to date because of the high uncertainties in the parameters from which it depends, mainly related to atmospheric density modeling and navigation errors. The purpose of this work is to investigate the feasibility of aerocapture at Mars with an innovative deployable drag device, whose aperture can be modulated in flight, and to assess the effects of the main uncertainties on the success of the maneuver. This paper starts with the presentation of a parametric bidimensional analysis of the effectiveness of aerocapture, for which a wide range of uncertainty levels in the atmospheric density and the ballistic coefficient are considered. Then, an application to a real mission scenario is carried out, including the error of the targeting maneuver performed at the limit of the sphere of influence of the planet. The analyses show the strong influence of the uncertainties in the atmospheric density and the ballistic coefficient, which significantly narrow the solution space and limit its continuity. However, viable solutions for aerocapture can still be identified, even in the worst conditions. This work has been supported by Khalifa University of Science and Technology’s internal grants FSU-2018-07 and CIRA-2018-85. J. Peláez and E. Fantino acknowledge also the support provided by the project entitled “Dynamical Analysis of Complex Interplanetary Missions,” with reference ESP2017-87271-P sponsored by Spanish Agencia Estatal de Investigación (AEI) of Ministerio de Economía, Industria y Competitividad (MINECO) and by European Fund of Regional Development (FEDER). The work was also supported by the internal grants of the Department of Engineering of the University of Naples.

Plantejament d'alternatives, en la construcció i disseny de la nau espacial Orion crew module, que està prevista com un dels components bàsics en les futures expedicions espacials a la Lluna i Mart. 1. Recerca bibliográfica i establiment de l'estat actual de l'art. 2. Selecció de materials alternatius. 3. Propostes de disseny alternatius. 4. Redacció de la memoria de TFG

Sand ingestion into military aircraft turbine engines from desert environments have tested the performance and life of the engine. In particular, turbine section blades and nozzles are coated with a molten glass when the sand is heated to melting temperatures. This molten glass attacks protective coatings on the surface of these parts. Further research is needed to understand the sands behavior on thermal barrier coatings (TBC) when heated to melting temperatures. Also, further research is needed with manufactured sand used in current engine testing to understand the sand ingestion discrepancies between test engines and operational engines. In this study natural sands from Yuma, Arizona, and Afghanistan will be heated to melting temperatures side-by-side with the manufactured sands specifically created for engine testing. All sands will be heated on EB-PVD TBC buttons provided by two companies who produce TBC coated turbine blades for current military engines. The results of manufactured sand should theoretically behave like natural sand and CMAS melted on a thermal barrier coating in order to substantiate past, current, and future testing. Additionally, the two EB-PVD TBCs behavior with the molten and cooled sand will be compared in this study.

A material that behaves likes a glassy ablator on the surface, has a low thermal conductivity, is structurally tough, lightweight, and is in some sense reusable, would be desirable for the protective heat shield used on Earth entry vehicles. A material for this purpose has been developed that uses silicon dioxide (fused quartz) in a fibrous packed matrix, forming blocks which can behave as a glassy ablator on the surface when subject to very high surface heat fluxes. These fibrous silicon dioxide blocks are called Reusable Surface Insulation (RSI). The primary constituent of the RSI material is silicon dioxide, but may contain other compounds (e.g. alumina borosilicate) to affect the thermal and physical properties. The research performed in this thesis is to determine the ablative behavior of ceramic RSI materials in a hypersonic high enthalpy flow that is used to simulate entry into Earth atmosphere. Actual arc jet experiments were performed to measure mass loss, melt run off, and fiber collapse of these materials and compare the experimental results with predicted theoretical values. The tests were performed to ascertain if RSI type materials could be used for entry vehicles proposed in NASA Mars missions. http://archive.org/details/ablativeheatshie1094534895 Lieutenant, United States Navy Approved for public release; distribution is unlimited.

Reaction sintered silicon nitride (RSSN) was studied as a substitute coating material on the carbon-carbon material (RCC) presently used as a heat shield on the space shuttle, and on advanced carbon-carbon (ACC), a later development. On RCC, RSSN showed potential in a 538°C (1000°F) screening test in which silicon carbide coated material exhibits its highest oxidation rate; RSSN afforded less protection to ACC because of a larger thermal expansion mismatch. Organosilicon densification and metallic silicon sealing methods were studied as means of further increasing the oxidation resistance of the coating, and some improvement was noted when these methods were employed. Master of Science