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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 217 records · Page 12
All sourcesNASA NTRSDOE OSTI
NASA NTRS1990

Structural dynamic and control considerations for Space Station transportation node concepts

This paper discusses the results of two studies which investigated the expected low frequency dynamic characteristics of conceptual Mars and lunar transportation nodes. Both concepts are based on evolution of the assembly-complete Space Station Freedom configuration by the addition of keels, booms, and modules. Finite-element models of the concepts were developed and a set of undamped modes and frequencies was computed below 2 Hz for each concept. The modes were used as basis vectors for modal analyses describing the dynamic response of the structures to typical reboost maneuvers. The reboost maneuvers had fairly complex loading characteristics since the reaction control system (RCS) jets used for the maneuvers were off-modulated to control pitch and yaw attitude. Interaction of the dynamic response of the structure with the closed-loop attitude control system is investigated for both concepts. The elastic response in the solar dynamic region is investigated to evaluate the severity of the dynamic environment, since the solar dynamic systems have stringent sunpointing requirements which must be maintained during the reboost maneuver.

Cooper, Paul A.↗
NASA NTRS1993

Node assignment in heterogeneous computing

A number of node assignment schemes, both static and dynamic, are explored for the Algorithm to Architecture Mapping Model (ATAMM). The architecture under consideration consists of heterogeneous processors and implements dataflow models of real-time applications. Terminology is developed for heterogeneous computing. New definitions are added to the ATAMM for token and assignment classifications. It is proved that a periodic execution is possible for dataflow graphs. Assignment algorithms are developed and proved. A design procedure is described for satisfying an objective function in an heterogeneous architecture. Several examples are provided for illustration.

Som, Sukhamoy↗
NASA NTRS1994

A six degree of freedom, plume-fuel optimal trajectory planner for spacecraft proximity operations using an A* node search

Spacecraft proximity operations are complicated by the fact that exhaust plume impingement from the reaction control jets of space vehicles can cause structural damage, contamination of sensitive arrays and instruments, or attitude misalignment during docking. The occurrence and effect of jet plume impingement can be reduced by planning approach trajectories with plume effects considered. An A* node search is used to find plume-fuel optimal trajectories through a discretized six dimensional attitude-translation space. A plume cost function which approximates jet plume isopressure envelopes is presented. The function is then applied to find relative costs for predictable 'trajectory altering' firings and unpredictable 'deadbanding' firings. Trajectory altering firings are calculated by running the spacecraft jet selection algorithm and summing the cost contribution from each jet fired. A 'deadbanding effects' function is defined and integrated to determine the potential for deadbanding impingement along candidate trajectories. Plume costs are weighed against fuel costs in finding the optimal solution. A* convergence speed is improved by solving approach trajectory problems in reverse time. Results are obtained on a high fidelity space shuttle/space station simulation. Trajectory following is accomplished by a six degree of freedom autopilot. Trajectories planned with, and without, plume costs are compared in terms of force applied to the target structure.

Jackson, Mark Charles↗
NASA NTRS1998

Accelerometer Placement for the International Space Station Node Modal Test

Accelerometer location analysis for the modal survey test of the International Space Station Node is described. Three different approaches were utilized: (1) Guyan reduction; (2) Iterative Guyan reduction; and (3) The average driving point residue (ADPR) method. Both Guyan approaches worked well, but poor results were observed for the ADPR method. Although the iterative Guyan approach appears to provide the best set of sensor locations, it is intensive computationally, becoming impractical for large initial location sets. While this is computer dependent, it appears that initial sets larger than about 1500 degrees of freedom are impractical for the iterative technique.

Tinker, Michael L.↗
NASA NTRS1997

Earth-Based Ring Occultation to the PDS Rings Node

The major task of this work has been to collect, document, and translate a wide variety of occultation data sets to a common format. This work has been completed. Table I lists the 1977-1987 Uranus occultation data sets that have been retrieved and which are ready for conversion to the PDS occultation standard format, once it has been standardized. The primary documentation and original data tapes for these occultations are part of the MIT data archive, and will be submitted to the PDS from MIT. I have been in contact with Jim Elliot and Steve McDonald, who are carrying out this work, and they have informed me that some of the original data tapes have bad blocks in them. As called upon, I will continue to provide the MIT group with whatever information they require in order that the most complete versions of the data sets be provided to the PDS. 2. All data sets from MIT NOVA disk platters were transcribed to Exabyte tapes, and software was written to enable the NOVA binary data formats to be converted to IEEE standard format. The number of these files which will be contributed to the PDS will depend on the success of the MIT group in reading the original data tapes for the events recorded on these disk platters. As needed, I will supply the MIT group with translated versions of these salvaged files for submission to the PDS. 3. The imaging observations from McDonald and Lick Observatories have been calibrated in both radius and optical depth, and are available in simple binary format. 4. Final submission of the Uranus ring data sets to the PDS is awaiting final agreement by the Rings Node Advisory Council on the PDS FITS format to be adopted for occultation data set.

French, Richard G.↗
NASA NTRS1998

STS-96: Expedition Crew #2 and 4 Work in Node #1 at the SSPF

Live footage of the crewmembers of STS-96, Commander Kent V. Rominger, Pilot Rick D. Husband, Mission Specialists Ellen Ochoa, Tamara E. Jernigan, Daniel T. Barry, Julie Payette, and Valery Ivanovich Tokarev, shows them in the node of the vehicle at the Space Station Processing Facility (SSPF). Scenes include the engineer explaining and the crew asking questions as to what certain labels mean. Footage also includes the crew observing the nose of the vehicle.

Source record↗
NASA NTRS2000

Overview on In-Space Internet Node Testbed (ISINT)

The Satellite Networks and Architecture Branch has developed the In-Space Internet Node Technology testbed (ISINT) for investigating the use of commercial Internet products for NASA missions. The testbed connects two closed subnets over a tabletop Ka-band transponder by using commercial routers and modems. Since many NASA assets are in low Earth orbits (LEO's), the testbed simulates the varying signal strength, changing propagation delay, and varying connection times that are normally experienced when communicating to the Earth via a geosynchronous orbiting (GEO) communications satellite. Research results from using this testbed will be used to determine which Internet technologies are appropriate for NASA's future communication needs.

Richard, Alan M.↗
NASA NTRS2001

Micro-Avionics Node for Distributed Avionics System

An avionics system is a platform residing on a flight vehicle that provides the resources (hardware and software) needed to manage the flight mission. Distributing the avionics system components, both functionally and spatially, can provide characteristics that benefit the overall system robustness, reliability, testability, and maintainability. This abstract discusses the concept of a distributed avionics system consisting of a network of micro-avionics nodes. Additional information is contained in the original extended abstract.

Blaes, B. R.↗
NASA NTRS2001

An Analysis of an Automatic Coolant Bypass in the International Space Station Node 2 Internal Active Thermal Control System

A challenging part of International Space Station (ISS) thermal control design is the ability to incorporate design changes into an integrated system without negatively impacting performance. The challenge presents itself in that the typical ISS Internal Active Thermal Control System (IATCS) consists of an integrated hardware/software system that provides active coolant resources to a variety of users. Software algorithms control the IATCS to specific temperatures, flow rates, and pressure differentials in order to meet the user-defined requirements. What may seem to be small design changes imposed on the system may in fact result in system instability or the temporary inability to meet user requirements. The purpose of this paper is to provide a brief description of the solution process and analyses used to implement one such design change that required the incorporation of an automatic coolant bypass in the ISS Node 2 element.

Clanton, Stephen E.↗
NASA NTRS2002

International Space Station (ISS) Nodes 2/3 Thermal Control System Overview and Design

The goals of this viewgraph presentation are to: (1) provide general International Space Station (ISS) Node 2 and 3 information; (2) give an overview of the ISS Thermal Control System (TCS) design, including details on the passive TCS and internal and external TCS; (3) give TCS components examples; and (4) describe the thermal and hydraulic analytical tools.

Clanton, Stephen↗
NASA NTRS2003

Status of the Node 3 Regenerative Environmental Cpntrol& Life Support System Water Recovery & Oxygen Generation Systems

NASA s Marshall Space Flight Center is providing three racks containing regenerative water recovery and oxygen generation systems (WRS and OGS) for flight on the lnternational Space Station s (ISS) Node 3 element. The major assemblies included in these racks are the Water Processor Assembly (WPA), Urine Processor Assembly (UPA), Oxygen Generation Assembly (OGA), and the Power Supply Module (PSM) supporting the OGA. The WPA and OGA are provided by Hamilton Sundstrand Space Systems lnternational (HSSSI), while the UPA and PSM are being designed and manufactured in-house by MSFC. The assemblies are currently in the manufacturing and test phase and are to be completed and integrated into flight racks this year. This paper gives an overview of the technologies and system designs, technical challenges encountered and solved, and the current status.

Carrasquillo, Robyn L.↗
NASA NTRS2004

Status of the Node 3 Regenerative ECLSS Water Recovery and Oxygen Generation Systems

NASA's Marshall Space Flight Center is providing three racks containing regenerative water recovery and oxygen generation systems (WRS and OGS) for flight on the International Space Station's (ISS) Node 3 element. The major assemblies included in these racks are the Water Processor Assembly (WPA), Urine Processor Assembly (UPA), Oxygen Generation Assembly (OGA), and the Power Supply Module (PSM) supporting the OGA. The WPA and OGA are provided by Hamilton Sundstrand Space Systems International (HSSSI), while the UPA and PSM are being designed and manufactured in-house by MSFC. The assemblies are completing the manufacturing phase and are in various stages of ORU and system level testing, to be followed by integration into the flight racks. This paper gives a current status, along with technical challenges encountered and lessons learned.

Carrasquillo, Robyn L.↗
NASA NTRS2006

An Accuracy Evaluation of Unstructured Node-Centred Finite Volume Methods

Node-centred edge-based finite volume approximations are very common in computational fluid dynamics since they are assumed to run on structured, unstructured and even on mixed grids. We analyse the accuracy properties of both first and second derivative approximations and conclude that these schemes can not be used on arbitrary grids as is often assumed. For the Euler equations first-order accuracy can be obtained if care is taken when constructing the grid. For the Navier-Stokes equations, the grid restrictions are so severe that these finite volume schemes have little advantage over structured finite difference schemes. Our theoretical results are verified through extensive computations.

Svard, Magnus↗
NASA NTRS1995

Parallel Climate Data Assimilation PSAS Package Achieves 18 GFLOPs on 512-Node Intel Paragon

Several algorithms were added to the Physical-space Statistical Analysis System (PSAS) from Goddard, which assimilates observational weather data by correcting for different levels of uncertainty about the data and different locations for mobile observation platforms. The new algorithms and use of the 512-node Intel Paragon allowed a hundred-fold decrease in processing time.

weather prediction climate modeling data assimilat↗
NASA NTRS2005

Development of GaN-based microchemical sensor nodes

Sensors based III-N technology are gaining significant interest due to their potential for monolithic integration of RF transceivers and light sources and the capability of high temperature operations. We are developing a GaN-based micro chemical sensor node for remote detection of chemical toxins, and present electrical responses of AlGaN/GaN HEMT (High Electron Mobility Transistor) sensors to chemical toxins as well as other common gases.

extreme environment↗
NASA NTRS2005

Development of GaN-based micro chemical sensor nodes

Sensors based on III-N technology are gaining significant interest due to their potential for monolithic integration of RF transceivers and light sources and the capability of high temperature operations. We are developing a GaN-based micro chemical sensor node for remote detection of chemical toxins, and present electrical responses of AlGaN/GaN HEMT (High Electron Mobility Transistor) sensors to chemical toxins as well as other common gases.

chemical↗
NASA NTRS2007

Lessons Learned from the Node 1 Sample Delivery Subsystem Design

This paper will provide an overview of the International Space Station (ISS) Environmental Control and Life Support (ECLS) design of the Node 1 Sample Delivery Subsystem (SDS) and it will document some of the lessons that have been learned to date for this part of the subsystem.

Williams, David E.↗