Cargo transfer vehicle RCS propellant contamination issues

The purpose of this report is to address Cargo Transfer Vehicle (CTV) RCS contamination issues and contribute to the resources necessary to optimize the vehicle and propulsion systems required in the CTV of the National Launch System (NLS) Heavy Lift Launch Vehicle (HLLV). This study reviews the thruster-induced contaminants; their transportation from the thrust chamber to the vehicle, payload, and SSF; and the mechanism by which damage is inflicted on their components. The effect of both monopropellant and bipropellant RCS rocket exhaust plumes on a spacecraft and related functional surfaces has been the subject of considerable study over the years. It is recognized that the RCS rocket produces contaminants which can significantly degrade the performance of optical windows, solar cells, thermal-protective coatings, and other external vehicle components. This is particularly true when the rocket is operating in the pulse mode. The exhaust plume impingement pressure and heat-transfer phenomena also complicate the environment to which the vehicle and its functional surfaces are exposed, but are not addressed in this study. Bipropellant contamination presented several modes of damage to incident surfaces, which can pose a long-term deleterious consequence to CTV payloads and the Space Station Freedom (SSF). Monopropellant contamination did not pose any significant long-term issues other than the possibility of aniline deposition. The use of either bipropellant and monopropellant propulsion systems can have a design impact on the CTV propulsion system with respect to maneuvering operations in the proximity of SSF

System Engineering and Technical Challenges Overcome in the J-2X Rocket Engine Development Project

Beginning in 2006, NASA initiated the J-2X engine development effort to develop an upper stage propulsion system to enable the achievement of the primary objectives of the Constellation program (CxP): provide continued access to the International Space Station following the retirement of the Space Station and return humans to the moon. The J-2X system requirements identified to accomplish this were very challenging and the time expended over the five years following the beginning of the J- 2X effort have been noteworthy in the development of innovations in both the fields for liquid rocket propulsion and system engineering

Particle acceleration and synchrotron emission in blazars

The conclusion is that the observations support the idea that the synchrotron emitting electrons are being accelerated at a collisionless shock front in a disordered field.An optical and infrared observing programme which provides the most detailed information yet available for blazars is described. From this it is possible to make progress in understanding the physical processes which are occuring on the smallest scales within the emission region. Later theoretical calculations including a treatm ent of synchrotron emission incorporating losses and a realistic source geometry are presented together with a model of particle acceleration at relativistic shocks in disordered magnetic fields. The work contained in this thesis can explain the radiation and make predictions regarding future observations

The Pathogenicity of Blue-Stain Fungi on Lodgepole Pines Attacked by Mountain Pine Beetle

In the western regions of North America, mountain pine beetle, Dendroctonus ponderosae Hopk., infestations take a tremendous toll of pines , especially lodgepole pine, Pinus contorta Dougl. var. latifolia Engelm.. Mass attack by the beetles is a devastating event for the trees. As well as girdling the tree, a massive inoculation of blue stain fungus complex (composed of several species of Ceratocystis, numerous yeasts and other mycelial fungi) is made beneath the bark. These fungi colonize and destroy the parenchyma tissue system of the host sapwood, primarily the ray parenchyma and resin duct epithelium. A blue stain is produced in the sapwood as a consequence of destruction of the sapwood parenchyma. The stain develops inward through the sapwood, and the transpiration stream is cut off. As more and more sapwood is stained, foliar water stress begins to increase. Foliage however, remains green and apparently healthy for up to 10 months after inoculation. When spring bud break begins the year following beetle attack, terminal buds of blue-stained trees begin to expand, then abort. Soon after, the needles of these trees fade to a reddish brown color. Transpiration stream disruption was not caused by penetration of tracheids by fungal hyphae; tyloses were not observed; nor was microconidial blockage of bordered pits seen. Though resin duct epithelium was eventually destroyed, little resin soaking was observed in the initial blue stained regions. Many bordered pits of tracheids in stained regions appeared to be aspirated, suggesting introduction of embolisms

SSME to RS-25: Challenges of Adapting a Heritage Engine to a New Vehicle Architecture

A key constituent of the NASA Space Launch System (SLS) architecture is the RS-25 engine, also known as the Space Shuttle Main Engine (SSME). This engine was selected largely due to the maturity and extensive experience gained through 30-plus years of service. However, while the RS-25 is a highly mature system, simply unbolting it from the Space Shuttle and mounting it on the new SLS vehicle is not a "plug-and-play" operation. In addition to numerous technical integration and operational details, there were also hardware upgrades needed. While the magnitude of effort is less than that needed to develop a new clean-sheet engine system, this paper describes some of the expected and unexpected challenges encountered to date on the path to the first flight of SLS

REIMR - A Process for Utilizing Liquid Rocket Propulsion-Oriented 'Lessons Learned' to Mitigate Development Risk in Nuclear Thermal Propulsion

This paper is a summary overview of a study conducted at the NASA Marshall Space Flight Center (NASA MSFC) during the initial phases of the Space Launch Initiative (SLI) program to evaluate a large number of technical problems associated with the design, development, test, evaluation and operation of several major liquid propellant rocket engine systems (i.e., SSME, Fastrac, J-2, F-1). One of the primary results of this study was the identification of the Fundamental Root Causes that enabled the technical problems to manifest, and practices that can be implemented to prevent them from recurring in future propulsion system development efforts, such as that which is currently envisioned in the field of nuclear thermal propulsion (NTF). This paper will discuss the Fundamental Root Causes, cite some examples of how the technical problems arose from them, and provide a discussion of how they can be mitigated or avoided in the development of an NTP syste

Next-Generation RS-25 Engines for the NASA Space Launch System

The utilization of heritage RS-25 engines, also known as the Space Shuttle Main Engine (SSME), has enabled rapid progress in the development and certification of the NASA Space Launch System (SLS) toward operational flight status. The RS-25 brings design maturity and extensive experience gained through 135 missions, 3000+ ground tests, and over 1 million seconds total accumulated hot-fire time. In addition, there were also 16 flight engines and 2 development engines remaining from the Space Shuttle program that could be leveraged to support the first four flights. Beyond these initial SLS flights, NASA must have a renewed supply of RS-25 engines that must reflect program affordability imperatives as well as technical requirements imposed by the SLS Block-1B vehicle (i.e., 111% RPL power level, reduced service life). Recognizing the long lead times needed for the fabrication, assembly and acceptance testing of flight engines, design activities are underway to improve system affordability and eliminate obsolescence concerns. These key objectives are enabled largely by utilizing modern materials and fabrication technologies, but also by innovations in systems engineering and integration (SE&I) practices

Operational Issues in the Development of a Cost-Effective Reusable LOX/LH2 Engine

Contents include the following: SLI initiated under NASA Research Announcement (NRA) 8-30. Strategic Objectives. Make spaceflight safer (1 in 10000 mission LOV). Make spaceflight cheaper ($1000/lb payload). Two prototype LOX/LH2 engine systems funded under Cycle-1 of NRA8-30. COBRA (Pratt & Whitney / Aerojet). RS-83 (Rocketdyne)