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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 253 records · Page 14
All sourcesNASA NTRSDOE OSTI
NASA NTRS2000

The Chandra Multi-Wavelength Project (ChaMP): A Serendipitous X-Ray Survey Using Chandra Archival Data

The launch of the Chandra X-ray Observatory in July 2000 opened a new era in X-ray astronomy. Its unprecedented, < 1" spatial resolution and low background is providing views of the X-ray sky 10-100 times fainter than previously possible. We have begun to carry out a serendipitous survey of the X-ray sky using Chandra archival data to flux limits covering the range between those reached by current satellites and those of the small area Chandra deep surveys. We estimate the survey will cover about 8 sq.deg. per year to X-ray fluxes (2-10 keV) in the range 10(exp -13) - 6(exp -16) erg cm2/s and include about 3000 sources per year, roughly two thirds of which are expected to be active galactic nuclei (AGN). Optical imaging of the ChaMP fields is underway at NOAO and SAO telescopes using g',r',z' colors with which we will be able to classify the X-ray sources into object types and, in some cases, estimate their redshifts. We are also planning to obtain optical spectroscopy of a well-defined subset to allow confirmation of classification and redshift determination. All X-ray and optical results and supporting optical data will be place in the ChaMP archive within a year of the completion of our data analysis. Over the five years of Chandra operations, ChaMP will provide both a major resource for Chandra observers and a key research tool for the study of the cosmic X-ray background and the individual source populations which comprise it. ChaMP promises profoundly new science return on a number of key questions at the current frontier of many areas of astronomy including solving the spectral paradox by resolving the CXRB, locating and studying high redshift clusters and so constraining cosmological parameters, defining the true, possibly absorbed, population of quasars and studying coronal emission from late-type stars as their cores become fully convective. The current status and initial results from the ChaMP will be presented.

Wilkes, Belinda↗
NASA NTRS2000

Design and Testing of the X-38 Spacecraft Primary Parafoil

In August of 1995 the NASA began testing large ram-air parafoils for potential use in the landing phase of spacecraft recovery. This effort eventually became a part of the X-38 project, a technology demonstrator for the International Space Station Emergency Crew Return Vehicle. This paper traces how the original parafoil, used in the U.S. Army Graded Precision Air Delivery System (GPADS), was modified to improve the initial deployment dynamics. A discussion of how test experience with 750 sq ft parafoils has been used to scale up to the full-scale 5500 sq ft and 7500 sq ft parafoils is presented. In particular, the development of two techniques that have greatly improved the repeatability of the parafoil initial deployment and decreased the first stage deployment dynamics are discussed: a first stage upper surface energy modulator and floor vents. Comparisons of trends and results from the various scale parachutes are presented as well as constraints that at times have driven the direction that the design has taken.

DESIGN OPTIMIZATION↗
NASA NTRS2000

Flight Experiment Platforms/Opportunities

This viewgraph presentation gives an overview of flight experiment platforms and opportunities, including details on flight experiments, ground test experiments, and the X-34 and X-37 projects.

Phipps, Michael↗
NASA NTRS1998

Space Transportation: Past, Present, and Future

This CD-ROM contains a multimedia presentation produced by NASA Marshall Space Flight Center. The production recounts the history of space transportation research from the early 20th Century to the present, including the current NASA/Orbital X-34 project. The CD includes motion pictures, animation and sound.

Source record↗
NASA NTRS2002

Propellant Densification for Shuttle: The SSME Perspective

The subject of cryogenic propellant densification as a potential upgrade to the Space Shuttle is a subject that has been raised on several occasions over the last decade. Due to advancements in densification technology made as a part of and in parallel to the X-33 project, the subject was raised and studied once again in May 2001. Across the Space Shuttle program people from many disciplines converged to discuss issues and perform trade studies to determine whether densified propellants was worth pursuing. This paper discusses one of these areas, specifically the Space Shuttle Main Engine (SSME). The effects of propellant densification on steady state performance are presented along with discussions of potential transient performance issues. Engine component redesign and retrofit issues are discussed as well the high level requirements to modify the ground test stands to accommodate propellant densification hardware and tanks. And finally, the matter of programmatic concerns enters the subject at hand as part of a discussion of SSME recertification requirements. In the end, potential benefits to SSME performance can be demonstrated and, subject to the densification scheme chosen, there does not appear to insurmountable technical obstacles.

Greene, William D.↗
NASA NTRS2004

Maximizing Knowledge to Improve Space Transportation System Development

A viewgraph presentation outlines the Boeing X-37 Project. The following are discussed: the project content, status, lessons learned, the integrated system schedule, external interface definition, risk management, full-time customer support at factory site, and lessons learned.

Turner, Susan↗
NASA NTRS2012

Composite Laminate With Coefficient of Thermal Expansion Matching D263 Glass

The International X-ray Observatory project seeks to make an X-ray telescope assembly with 14,000 flexible glass segments. The glass used is commercially available SCHOTT D263 glass. Thermal expansion causes the mirror to distort out of alignment. A housing material is needed that has a matching coefficient of thermal expansion (CTE) so that when temperatures change in the X-ray mirror assembly, the glass and housing pieces expand equally, thus reducing or eliminating distortion. Desirable characteristics of this material include a high stiffness/weight ratio, and low density. Some metal alloys show promise in matching the CTE of D263 glass, but their density is high compared to aluminum, and their stiffness/weight ratio is not favorable. A laminate made from carbon fiber reinforced plastic (CFRP) should provide more favorable characteristics, but there has not been any made with the CTE matching D263 Glass. It is common to create CFRP laminates of various CTEs by stacking layers of prepreg material at various angles. However, the CTE of D263 glass is 6.3 ppm/ C at 20 C, which is quite high, and actually unachievable solely with carbon fiber and resin. A composite laminate has been developed that has a coefficient of thermal expansion identical to that of SCHOTT D263 glass. The laminate is made of a combination of T300 carbon fiber, Eglass, and RS3C resin. The laminate has 50% uni-T300 plies and 50% uni-E-glass plies, with each fiber-layer type laid up in a quasi-isotropic laminate for a total of 16 plies. The fiber volume (percent of fiber compared to the resin) controls the CTE to a great extent. Tests have confirmed that a fiber volume around 48% gives a CTE of 6.3 ppm/ C. This is a fairly simple composite laminate, following well established industry procedures. The unique feature of this laminate is a somewhat unusual combination of carbon fiber with E-glass (fiberglass). The advantage is that the resulting CTE comes out to 6.3 ppm/ C at 20 C, which matches D263 glass. The trick with this laminate is to establish the proper fiber volume to get the desired CTE. Laminates were made with several different fiber volumes and coupons were tested to establish the relationship between fiber volume and CTE. Testing proved that fiber volume should be about 48%.

Robinson, David↗
NASA NTRS2019

Seeker Free-Flying Inspector GNC System Overview

Seeker is an ultra-low cost approach to highly automated extravehicular inspection of crewed or uncrewed spacecraft that has been designed and built in-house at the NASA Johnson Space Center (JSC). The first version of Seeker is intended to be an incremental development towards an advanced inspection capability. This effort builds on past free-flying inspector development efforts such as the Autonomous Extravehicular Activity Robotic Camera Sprint (AERCam Sprint) and Mini AERCam. Seeker was funded as an International Space Station (ISS) "X-by" Project, which required delivery of the vehicle approximately one year after authority to proceed and within the budget of $1.8 million. Seeker will fly onboard the NG-11 Cygnus mission in 2019 and will deploy after Cygnus' primary mission is completed. Seeker will perform inspection-like maneuvers within 50 meters of the target vehicle (Cygnus) and then dispose itself. The Seeker Guidance, Navigation, and Control (GNC) system is composed entirely of commercial off-the-shelf (COTS) and space-rated COTS items, an inertial-relative Multiplicative Extended Kalman Filter (MEKF), point-to-point guidance (with various additional modes such as stationkeeping), proportional-integral translational control, phase plane rotational control, and a state machine for automated mission moding with minimal ground input.

Navigation↗
NASA NTRS2012

XHAB 2012 Final Report Habitat Demonstration Unit Lite

The University of Maryland Space Systems Laboratory (SSL) was awarded a NASA X-Hab 2012 grant for the design and construction of a new Earth analogue habitat for habitability research. This work builds on the past ECLIPSE and X-Hab projects at the SSL, by combining these elements with a new habitat module in order to create a single research platform for habitability studies. The “Crew Habitat Evaluator for Long-duration Orbital, Near-earth, and Interplanetary Applications” (CHELONIA) will deliver a much more flexible architecture than the previously developed mock-ups, allowing facilitating faster modification of the interior layouts and available total volume. This will enable the investigators to evaluate crew assessments and task performance as a function of the interior layout, functional area allocation and total available volume. This paper documents the design of this new infrastructure, and includes the details of the manufacturing of a new habitat mock-up module and modifications to the existing elements. The paper also includes a brief discussion of possible future research goals. Initial layouts are implemented using foam-core volumetric mock-ups for internal equipment and outfitting. These low fidelity mock-ups constitute a “library” that will allow a very rapid evaluation of a multitude of layouts. CHELONIA is also suitable for higher fidelity functional mock-ups, as well as short to medium-duration mission simulations. This new facility will enable the examination of habitat layouts for both partial gravity and microgravity environments. While partial gravity systems will be easily evaluated with the habitat currently in development, microgravity subsystems will be studied by utilizing low fidelity volumetric neutral buoyancy mock-ups in order to determine if commonality in the design for these two environments is appropriate. Finally, this new facility is being integrated into the SSL Moonyard planetary surface simulation center. The Moonyard simulates a planetary surface by means of a large sandbox, and is used primarily for rover field trials and suit systems evaluation. This new facility will be a prime element in future Earth analog simulations at the University of Maryland in support of NASA exploration objectives.

Kevin Davis↗
NASA NTRS2023

Regenerable Liquid Desiccants for High Efficiency Humidity Control in Microgravity

The NASA X-Hab project aims to design, manufacture, test, and prove functionality of an air humidity control subsystem to dehumidify and re-humidify air from a space cabin. The method of regulating cabin air humidity utilizes vortex phase separation, which uses an ionic liquid (IL) desiccant for air-water phase separation. This subsystem is intended to be integrated with a CO 2 removal system requiring de-humidified air to operate efficiently. The air humidity control subsystem is composed of a cold-desiccant or cold-side Vortex Phase Separator (VPS) that dehumidifies the cabin air. The dehumidified air exits the cold-side (CS) VPS chamber to flow into the CO 2 removal module, and the cold, water-laden liquid desiccant flows to a regenerative heat exchanger. From the heat exchanger the liquid desiccant continues to the heater. After heating, the desiccant flows into a hot-desiccant or hot-side (HS) VPS as the dehumidified air from CO 2 removal module enters through the HS VPS air inlet. The rehumidified air exits the HS VPS into the space cabin. One pump installed at the liquid exit of the CS VPS and one pump installed at the liquid exit of the HS VPS transport the fluid through the system. To evaluate the system’s efficiency and effectiveness, the temperature, pressure, flow rate and relative humidity are read, recorded, and analyzed at critical points along the module.

Gerardo Castro↗
DOE OSTI2016

Application of SPH Factors to PHWR Lattice Homogenization

Pressurized Heavy-Water Reactors (PHWRs) are heavy-water moderated and cooled. They consist of a horizontal, cylindrical, non-pressurized calandria vessel which contains the heavy-water moderator and is penetrated axially by fuel channels. Fuel channels consist of two concentric tubes separated by a gas gap: an inner tube called the pressure tube, and an outer tube called the calandria tube. The pressure tubes hold the fuel bundles, which are cooled by the flow of coolant at high temperature and pressure. The coolant flows in opposite directions in adjacent channels. The gap between the pressure and calandria tubes ensures that the temperature of the moderator remains relatively low, below 80 deg. C. For a CANDU 6 reactor, there are 380 fuel channels, each holding 12 37-element fuel bundles, approximately 10-cm in diameter and 50-cm long each. The fuel pins are arranged in three concentric rings (consisting of 6, 12 and 18 pins respectively), plus a central pin. The distance between channels (lattice pitch) is approximately 28.6 cm. Production core-level neutronics calculations are usually performed in a Cartesian geometry using few group diffusion and a simplified core model, whereby neutronics properties are homogenized over large regions called nodes. For Light Water reactors (LWRs), the two-dimensional axial (x-y) projection of a node corresponds to one fuel assembly. For PHWRs, a node usually consists of one fuel bundle and its associated moderator. For LWRs, advanced core-level calculations based on advanced node-level homogenization methods, such as Generalized Equivalence Theory (GET) or Super-homogenisation (SPH), improve the accuracy of full-core calculations compared to - standard homogenization. For rectangular fuel-pin arrangements, SPH can be used to perform pin-cell level homogenization which allows subsequent core-level diffusion calculations to be performed using fine Cartesian meshes. For PHWRs, the distribution of fuel pins in concentric rings makes the use of Cartesian mesh refinement impractical. However, SPH can still be applied, albeit using a coarser node subdivision, by dividing the heterogeneous node into 3x3 sub-regions in such a way that the central sub-region includes the entire fuel channel. This work investigates the use of SPH homogenization using a 3x3 subdivision of the PHWR node. Preliminary results show that the use of SPH factors does not yield more accurate results than standard homogenization when applied to PHWR nodes using a 3x3 subdivision. The explanation appears to lie in the fact that SPH factors are dependent on node-boundary leakage. Future investigations to confirm the leakage-dependence of SPH factors are recommended. Accuracy improvements may also be achievable by using smaller SPH regions at the periphery of the PHWR node, in an attempt to reduce the SPH factors' dependence on node-boundary leakage. (authors)

21 SPECIFIC NUCLEAR REACTORS AND ASSOCIATED PLANTS↗