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NASA NTRSDate not supplied

Centrifugal Nuclear Thermal Rocket Challenges and Potential

The Centrifugal Nuclear Thermal Rocket (CNTR) is a liquid fueled fission propulsion concept designed to heat propellant to 5000 K prior to expansion through a nozzle. A specific impulse up to 1800 s may be achieved using hydrogen propellant, and a specific impulse up to 1000 s may be achieved using more storable propellants such as methane, ammonia, or propane. The high uranium density of the liquid metallic uranium or liquid uranium carbide fuel will help enable compact engines suitable for missions such as fast (<15 month) round trip human Mars missions or high delta-V missions in cislunar space. Long term applications of the CNTR could include the advanced exploration and utilization of the solar system through direct use of in-situ volatiles as propellant. Challenges associated with the CNTR are numerous. Centrifugal force is used to retain the liquid fuel in rotating fuel cylinders, and rotational velocities up to 5000 rpm may be required. Propellant flow must be directed such that all structures and moderators in the core are adequately cooled prior to the propellant entering the liquid fuel and being heated to 5000 K. The rotating fuel cylinder wall (RFCW) must have an inner surface designed to be compatible with liquid uranium metal or uranium carbide fuel up to at least 1500 K, and that inner surface may also need to be textured to help maintain acceptable wall temperatures. Propellant must flow radially inward through the RFCW while fuel is simultaneously contained. The RFCW should ideal-ly be made from a material with low neutron absorption to help minimize engine mass and facilitate the use of High Assay Low Enriched Uranium (HALEU) fuel in the system. The drive system for the rotating fuel cylinders must support all phases of operation. This paper will discuss computational and experimental research being conducted to address some of the challenges associated with the CNTR, and will also note potential mission benefits from the CNTR.

Michael G. Houts↗

NASA NTRS1990

The organized nature of a turbulent trailing vortex

The turbulence structure of a trailing vortex produced at the juncture of a flow aligned cylinder and a pair of oppositely loaded airfoils is analyzed. The freestream turbulence intensity in this study varies from 0.32 to 1.48 percent, the vortex Reynold number varies from 15000 to 25000, and the Rossby number varies from 0.65 to 0.81. Within this parameter range, it is shown that the screens, but not the freestream turbulence level, are able to produce significant variations in the turbulence structure of the vortex, and that the turbulent structure is determined by the Rossby number and not the vortex Reynolds number. It is noted that the core is dynamic and an organized exchange of momentum takes place between the outer flow and the core region of the vortex. The vortex structure in the trailing vortex having the lowest Rossby number is considered.

Bandyopadhyay, Promode R.↗

NASA NTRS1994

Hot gas outflow in the blue compact dwarf galaxy VII Zw 403

We have observed the Blue Compact Dwarf Galaxy VII Zw 403 with the Position Sensitive Proportional Counter (PSPC) camera onboard ROSAT. We found a total X-ray luminosity of 1.94 x 10(exp 38) erg/s distributed in a central core to which are connected three elongated structures. We interpret this X-ray morphology as the result of a hot gas outflow from the core of the dwarf galaxy powered by the present starburst.

Papaderos, P.↗

NASA NTRS2009

Application of Air Coupled Acoustic Thermography (ACAT) for Inspection of Honeycomb Sandwich Structures

The application of a noncontact air coupled acoustic heating technique is investigated for the inspection of advanced honeycomb composite structures. A weakness in the out of plane stiffness of the structure, caused by a delamination or core damage, allows for the coupling of acoustic energy and thus this area will have a higher temperature than the surrounding area. Air coupled acoustic thermography (ACAT) measurements were made on composite sandwich structures with damage and were compared to conventional flash thermography. A vibrating plate model is presented to predict the optimal acoustic source frequency. Improvements to the measurement technique are also discussed.

Winfree, William P.↗

NASA NTRS2006

Finite Element Development of Honeycomb Panel Configurations with Improved Transmission Loss

The higher stiffness-to-mass ratio of a honeycomb panel compared to a homogeneous panel results in a lower acoustic critical frequency. Above the critical frequency the panel flexural wave speed is acoustically fast and the structure becomes a more efficient radiator with associated lower sound transmission loss. Finite element models of honeycomb sandwich structures are presented featuring areas where the core is removed from the radiating face sheet disrupting the supersonic flexural and shear wave speeds that exist in the baseline honeycomb panel. These modified honeycomb panel structures exhibit improved transmission loss for a pre-defined diffuse field sound excitation. The models were validated by the sound transmission loss of honeycomb panels measured in the Structural Acoustic Loads and Transmission (SALT) facility at the NASA Langley Research Center. A honeycomb core panel configuration is presented exhibiting a transmission loss improvement of 3-11 dB compared to a honeycomb baseline panel over a frequency range from 170 Hz to 1000 Hz. The improved transmission loss panel configuration had a 5.1% increase in mass over the baseline honeycomb panel, and approximately twice the deflection when excited by a static force.

Grosveld, Ferdinand W.↗

NASA NTRS1991

U-band CCD surface brightness profiles for candidate collapsed-core globular clusters

We have determined U-band CCD surface brightness profiles for 15 of the 21 globular clusters that have been characterized as having 'collapsed' cores by Djorgovski and King (1986). We have fitted these profiles with two types of seeing-convolved models: single-mass King models and power laws. We find that in many cases the characterization of a profile as being either 'King' or 'cusp' is somewhat subtle. Of the clusters in our sample, 10 appear to have central power-law cusps with either unresolved or marginally resolved cores, three appear to have resolved cores with surrounding power-law structure that is unlike a King model, and two are approximately described by King model fits. The observed power-law cusps are consistent with the predictions of Fokker-Planck models for core-collapse.

Lugger, Phyllis M.↗

NASA NTRS1977

Structure of the X-ray source in the Virgo cluster of galaxies

High-angular-resolution observations in the 0.15-1.5-keV band with an imaging X-ray telescope shows the extended X-ray source in the Virgo cluster of galaxies to be a diffuse halo of about 15 arcmin core radius surrounding M87. The angular structure of the surface brightness is marginally consistent with either of two simple models: (1) an isothermal (or adiabatic or hydrostatic) sphere plus a point source at M87 accounting for 12% of the total 0.5-1.5-keV intensity or (2) a power-law function without a discrete point source. No evidence for a point source is seen in the 0.15-0.28-keV band, which is consistent with self-absorption by about 10 to the 21st power per sq cm of matter having a cosmic abundance. The power-law models are motivated by the idea that radiation losses regulate the accretion of matter onto M87 and can account for the observed difference in the size of the X-ray source as seen in the present measurements and at higher energies.

Gorenstein, P.↗

NASA NTRS1974

Preservation of lunar core samples - Preparation and interpretation of three-dimensional stratigraphic sections

Preservation and analysis of core samples collected from the lunar regolith are discussed. The objectives of core sampling are described together with the core-sampling equipment used in the Apollo program. The effects of disaggregation in core samples are summarized, and ways to preserve the stratigraphy in these samples are reviewed, particularly partial impregnation of samples with polybutyl methacrylate. It is shown that stratigraphic sections preserved in this way reveal individual fragments of the regolith in their original positions, primary and secondary depositional structures related to lunar processes, and the nature and extent of deformations caused by sampling equipment. It is concluded that since the core sedimentary structures indicate complex three-dimensional variations in the regolith, quantitative models of regolith evolution must allow for distinctive local histories as well as irregular reworking and deposition events due to impact processes.

Fryxell, R.↗

NASA NTRS2010

The Wasp-Waist Nebula: VLA Ammonia Observations of the Molecular Core Envelope In a Unique Class 0 Protostellar System

The Wasp-Waist Nebula was discovered in the IRAC c2d survey of the Ophiuchus starforming clouds. It is powered by a well-isolated, low-luminosity, low-mass Class 0 object. Its weak outflow has been mapped in the CO (3-2) transition with the JCMT, in 2.12 micron H2 emission with WIRC (the Wide-Field Infrared Camera) on the Hale 5-meter, and, most recently, in six H2 mid-infrared lines with the IRS (InfraRed Spectrograph) on-board the Spitzer Space Telescope; possible jet twisting structure may be evidence of unique core dynamics. Here, we report results of recent VLA ammonia mapping observations of the dense gas envelope feeding the central core protostellar system. We describe the morphology, kinematics, and angular momentum characteristics of this unique system. The results are compared with the envelope structure deduced from IRAC 8-micron absorption of the PAH (polycyclic aromatic hydrocarbon) background emission from the cloud.

Wiseman, Jennifer↗

NASA NTRS2004

Small-scale Interstellar Structure Toward the Open Cluster Chi Persei; Program ID: BO29 (Cycle 2)

The primary objective of this program was to obtain FUSE observations of the interstellar H2 absorption toward six early-type stars in the core of the open star cluster Chi Persei. High resolution optical observations of the interstellar Na I absorption toward these stars and others in the core of Chi Per have revealed a rich variety of small-scale diffuse ISM structure in both the distant Perseus and more local Orion spiral arms. At the 1 arc minute angular scales typically probed by the separations of these stars, this structure corresponds to respective physical length scales of 0.6 and 0.15 pc in the Perseus and Orion arm gas. The principal scientific goal of the FUSE observations was to determine if this small-scale Na I structure toward the core of Chi Per was reflected in the abundance and/or excitation of interstellar H2. In September 2001, we obtained FUSE observations of the Chi Per stars BD +56 563, BD +56 571, BD +56 573, BD +56 574, BD +56 575, and BD +56 578 for this program. The data reveal that the Perseus arm gas exhibits significant small-scale variations in the strength of its molecular hydrogen absorption while the Orion arm H2 absorption is relatively uniform. We presented these results at the January 2003 American Astronomical Society meeting in Seattle, WA (points, Meyer, Lauroesch, Nguyen, and Friedman 2002, Bulletin of the American Astronomical Society, 34,1229). Since Na I is not a dominant ion in H I clouds, the variations detected in the Perseus arm Na I line profiles could be due to spatial differences in either the physical structure or the physical conditions in the gas. Although many of the H2 absorption profiles are too saturated or too weak to be definitive in this regard, it is clear that small-scale variations are present in H2 gas with excitation as high as the J=4 rotational level. In contrast, lower spatial resolution H I 21 cm studies of the Perseus arm gas across the face of the h and Chi Per double cluster have shown smoother, continuous variations on the larger scale. In order to investigate if the global velocity structure of H2 toward h and Chi Per more closely follows the chaotic structure seen in interstellar Na I absorption or the smoother, continuous H I structure, we have expanded our FUSE study with a Cycle 4 program (D902, PI: Points) to survey the H2 absorption toward a number of other stars across the face of the double cluster. We have obtained FUSE spectra of 14 additional h and Chi Per stars through this program and are now combining all of the data into a comprehensive study that will be submitted for publication next year.

Meyer, David M.↗

NASA NTRS2019

NASA’s Space Launch System: Exploration Mission-1 Hardware Nears Completion

The Space Launch System (SLS) Program completed several significant production milestones in 2018 for the launch vehicle’s first mission (Fig. 1) and is poised for greater accomplishments in 2019. With manufacturing and hardware installation finished, Boeing completed the core stage forward join and shipped the liquid hydrogen tank structural test article to Marshall Space Flight Center for testing. The core stage aft join and LOX tank STA are expected to be completed in 2019 on the way to final stage integration. The four EM-1 engines are poised for stage integration in 2019. The Launch Vehicle Stage Adapter completed outfitting at Marshall and will be shipped to Kennedy Space Center in 2019. All solid rocket motor segments for the EM-1 boosters are cast, inspected and ready for shipment to KSC. The upper stage, the Interim Cryogenic Propulsion Stage (ICPS), and the Orion Stage Adapter (OSA), where 13 6U CubeSats will ride to deep space on EM-1, were completed and delivered to Exploration Ground Systems at KSC in 2017 and 2018, respectively. The Program continues to work toward first launch of the nation’s new super heavy lift deep space capability in fiscal 2020. SLS is designed, engineered and tested to launch the most challenging exploration missions, minimizing risk and providing the greatest opportunity for mission success. This paper will discuss the technical and programmatic successes and challenges of the past year and look ahead to plans for 2019.

Honeycutt, John↗

NASA NTRS2019

NASA’s Space Launch System: First Mission Hardware Nears Completion

The Space Launch System (SLS) Program (Fig. 1) completed several significant production milestones in 2018 for its first mission and is poised for greater accomplishments in 2019. With manufacturing and hardware installation complete, Boeing completed the core stage forward join and shipped the liquid hydrogen tank structural test article to Marshall Space Flight Center for testing. The core stage aft join and LOX tank STA are expected to be completed in 2019 on the way to final stage integration. The four EM-1 engines are poised for stage integration in 2019. The Launch Vehicle Stage Adapter completed outfitting at Marshall and will be shipped to Kennedy Space Center in 2019. All solid rocket motor segments for the EM-1 boosters are cast, inspected and ready for shipment to KSC. The Program continues to work toward first launch of the nation’s new super heavy lift deep space capability in fiscal 2020. SLS is designed, engineered and tested to launch the most challenging exploration missions, minimizing risk and providing the greatest opportunity for mission success and scientific discovery. This paper will discuss the technical and programmatic successes and challenges of the past year and look ahead to plans for 2019.

Honeycutt, John↗

NASA NTRS1981

The large- and small-scale structures of 3C 293

A Very Large Array (VLA) 1.465-GHz map of the radio galaxy 3C 293 shows that the source, which is unusual in that it is dominated by a steep-spectrum extended core, has a two-sided Z-shaped structure whose physical association with the galaxy VV 5-33-12 is now clear. The core is resolved by the Multi-Element Radio Linked Interferometer Network (MERLIN) at 1.666-GHz, and the VLA at 15.035 GHz, into an inner, two-sided structure within 1 kpc of the center of VV 5-33-12, and curved bridges of emission linking this structure to the large-scale emission. The major axis of the core lies 35 deg from the major axes of the emission bridges that make up the bar of the large-scale Z structure, and 60 deg from the minor axis of VV 5-33-12. Precessional and buoyant-refraction models for these misalignments are discussed.

Bridle, A. H.↗

NASA NTRS2018

EDEN Mars Transit Habitat Concept of Operations

Jackson Behre↗

NASA NTRS2018

Food Sanitation Device for Use in Microgravity

EDEN is a transportation/orbital habitat that carries large amounts of crew members, food, and supplies from Earth to Mars and back, but can also act as a permanent, simulated-1g-environment space station in Martian orbit. The focus of the project is to create a temporary, but long-term living environment that focuses on human health and food production. The project is composed of four major habitable parts (in addition to other major components). Moving from the center out, the first is a central core that acts as a hub that connects to the structural spokes, the main propulsion rockets and serves as a place for other spacecraft to dock onto, in addition to housing some of the basic station control, navigation and automated computer systems. The second set of parts are the spokes that connect the ring to the central core; these are the primary structural components with elevators in the middle carrying people from the ring to the core. The ‘lower’ portions, near the ring and it’s 1g environment, also act as storage centers. The third part is the 2-story outer ring This project served as an engineering senior design project at Temple University, and as part of NASA’s eXploration and Habitation (X-Hab) 2018 Academic Innovation Challenge. The goal of the project was to design, construct, and test a device which would be used in microgravity to sanitize produce. This is part of a NASA’s effort to grow and sanitize fresh produce on the International Space Station (ISS), in order to provide more nutritious meal options to the astronauts. Our team designed a 3-D printed spherical device with UV-C LEDs lining the interior. The designed device consists of an 8” spherical chamber, 10 UV-C LEDs, and a touchscreen user interface to control the device. Our design meets the project requirements by offering several features: a simple user interface, minimal crew time to operate, no waste produced, and the ability to sanitize multiple types of produce. The main reductions in Salmonella bacteria and Aspergillus Flavus mold were not verified. However, the aerobic plate count requirement was greatly exceeded and validated. Testing of the device resulted in visual results confirming significant decrease in E. coli activity with increased UV-C exposure, as well as quantitative results confirming significant reduction in CFU/g for the aerobic plate count. These reductions achieved from 1.464 x 10 7 to 2 x 10 4 CFU/g (2.86 log reduction) after 5 minutes, were significantly more than the requirements given by NASA ( of the craft, which holds all of the food production along with medical bays, a control center and a few parks. This ring also integrates the rigid keystone modules, which are the interface between the spokes, the expandable-construction portions of the ring and the habitation pods. The keystone modules also incorporate redundant, distributed ECLSS systems, medical storage, airlocks, and other integral station functions. The last parts are the habitation pods; these hold the sleeping quarters along with the bathrooms, showers, kitchen space and lounge areas. These expandable modules latch onto the keystone modules of the ring, which serves as a circulatory link between the different habitation pods.

Damien Gordon↗

NASA NTRSDate not supplied

TriTruss Packaging and Deployment Trade Study

A trade study was conducted that evaluated viable concepts of operation for the packaging and deployment (P&D) of novel deployable modular truss modules, called TriTruss modules, that can be assembled to form a large aperture In-Space Assembled Telescopes (iSAT). In this first phase of an ongoing more comprehensive trade study, concepts were proposed and then evaluated based on initial metrics representing features of an ideal P&D concept. The ideal TriTruss P&D concept is defined as one that: allows for efficient packaging, has sufficient geometric versatility to be launch vehicle independent, provides a stiff and lightweight structure, has low mechanical complexity, and has component modularity. The P&D concept should allow for prelaunch subsystem or utility integration if required. The concept should be kinematically simple and be robotically deployed using a minimum number of specialized tools. The P&D concepts evaluated are categorized as: core collapse, face collapse, and erectable structures. Sub-scale models were constructed to help understand the kinematics and mechanical complexity required to enable P&D. Based on a weighting scale, the most promising candidate P&D concepts have been selected and will undergo more rigorous structural design, analysis, and testing in the study’s next phase. The ultimate goal of the comprehensive trade study will be to recommend a single TriTruss design and associated P&D concept that will be built and evaluated at NASA Langley Research Center’s In-Space Assembly Laboratory.

in-space assembly (ISA)↗

NASA NTRS2004

Carbon-Carbon Composite Radiator Development for the EO-1 Spacecraft

The Carbon-Carbon Space Radiator Partnership (CSRP), an informal partnership of Government and industrial personnel, was formed to promote the use of Carbon-carbon composites (C-C) as engineering materials for spacecraft thermal management applications . As a part of this effort the partnership has built a structural radiator for the Earth Orbiter - 1 (EO-1) spacecraft. This radiator, using C-C face-sheets with an aluminum honeycomb core, will demonstrate both the thermal and structural properties of C-C under actual service conditions as well as provide performance data from space flight. This paper will present results from the design of the radiator, the thermal/mechanical tests of the facesheet materials, and sub-component test results on the C-C/Al honeycomb sandwich material. The 29- by 28-inch radiator was designed to support two electronics boxes with a combined heat output of 60 watts maximum and a weight of 58 lbs. The analysis of the radiator design shows that the radiator constructed with 20-mil-thick facesheets of a P30-fiber-reinforced C-C from BFGoodrich is able to meet or exceed all the required thermal and mechanical requirements.

Vaughn, Wallace↗

NASA NTRS1980

Influence of pressure driven secondary flows on the behavior of turbofan forced mixers

An analytical and experimental study was performed to determine the influence of pressure driven secondary flows on the behavior of turbofan forced mixer nozzles. The basic secondary flow structure entering the nozzle was identified experimentally and was composed of a strong vortex system aligned with the radial interface between the fan and core streams. A generic secondary flow vortex structure was constructed for input to the analysis to represent the large scale structure of this inflow condition. Comparison between experiment and analysis at five axial stations showed very good agreement and indicated that this vortex system was convected downstream and dominated the mixing process.

Anderson, B.↗