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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 37 records · Page 2
All sourcesNASA NTRSDOE OSTI
NASA NTRS1982

New Technology for the Fire Attire

Although little can be done to reduce the risks of firefighting, something can be done to curb the injuries and fatalities. This is the goal of Project FIRES, a program jointly sponsored by NASA and the Federal Emergency Management Agency's U.S. Fire Administration with technical management provided by Marshall Space Flight Center. Project FIRES (Firefighter's Integrated Response Equipment System) involves applications of advanced materials and design concepts, derived from Apollo to update existing gear which does not adequately protect against many of the hazards encountered in fire suppression activities. A major focus of the effort involves application to the FIRES ensemble of lightweight, fire-resistant, heat-protective materials originally developed for use in astronauts' space suits or in spacecraft components which require thermal protection. Data from the fourteen municipal fire departments participating in the field evaluation will form a basis for development of new nationwide protective ensemble students.

Source record↗
NASA NTRS2005

Performance Analysis of Direct-Sequence Code-Division Multiple-Access Communications with Asymmetric Quadrature Phase-Shift-Keying Modulation

This article considers a quaternary direct-sequence code-division multiple-access (DS-CDMA) communication system with asymmetric quadrature phase-shift-keying (AQPSK) modulation for unequal error protection (UEP) capability. Both time synchronous and asynchronous cases are investigated. An expression for the probability distribution of the multiple-access interference is derived. The exact bit-error performance and the approximate performance using a Gaussian approximation and random signature sequences are evaluated by extending the techniques used for uniform quadrature phase-shift-keying (QPSK) and binary phase-shift-keying (BPSK) DS-CDMA systems. Finally, a general system model with unequal user power and the near-far problem is considered and analyzed. The results show that, for a system with UEP capability, the less protected data bits are more sensitive to the near-far effect that occurs in a multiple-access environment than are the more protected bits.

Wang, C.-W.↗
NASA NTRS1994

Lessons from an evolving rRNA: 16S and 23S rRNA structures from a comparative perspective

The 16S and 23S rRNA higher-order structures inferred from comparative analysis are now quite refined. The models presented here differ from their immediate predecessors only in minor detail. Thus, it is safe to assert that all of the standard secondary-structure elements in (prokaryotic) rRNAs have been identified, with approximately 90% of the individual base pairs in each molecule having independent comparative support, and that at least some of the tertiary interactions have been revealed. It is interesting to compare the rRNAs in this respect with tRNA, whose higher-order structure is known in detail from its crystal structure (36) (Table 2). It can be seen that rRNAs have as great a fraction of their sequence in established secondary-structure elements as does tRNA. However, the fact that the former show a much lower fraction of identified tertiary interactions and a greater fraction of unpaired nucleotides than the latter implies that many of the rRNA tertiary interactions remain to be located. (Alternatively, the ribosome might involve protein-rRNA rather than intramolecular rRNA interactions to stabilize three-dimensional structure.) Experimental studies on rRNA are consistent to a first approximation with the structures proposed here, confirming the basic assumption of comparative analysis, i.e., that bases whose compositions strictly covary are physically interacting. In the exhaustive study of Moazed et al. (45) on protection of the bases in the small-subunit rRNA against chemical modification, the vast majority of bases inferred to pair by covariation are found to be protected from chemical modification, both in isolated small-subunit rRNA and in the 30S subunit. The majority of the tertiary interactions are reflected in the chemical protection data as well (45). On the other hand, many of the bases not shown as paired in Fig. 1 are accessible to chemical attack (45). However, in this case a sizeable fraction of them are also protected against chemical modification (in the isolated rRNA), which suggests that considerable higher-order structure remains to be found (although all of it may not involve base-base interactions and so may not be detectable by comparative analysis). The agreement between the higher-order structure of the small-subunit rRNA and protection against chemical modification is not perfect, however; some bases shown to covary canonically are accessible to chemical modification (45).(ABSTRACT TRUNCATED AT 400 WORDS).

Review↗
NASA NTRS2012

Autonomous Information Unit for Fine-Grain Data Access Control and Information Protection in a Net-Centric System

As communication and networking technologies advance, networks will become highly complex and heterogeneous, interconnecting different network domains. There is a need to provide user authentication and data protection in order to further facilitate critical mission operations, especially in the tactical and mission-critical net-centric networking environment. The Autonomous Information Unit (AIU) technology was designed to provide the fine-grain data access and user control in a net-centric system-testing environment to meet these objectives. The AIU is a fundamental capability designed to enable fine-grain data access and user control in the cross-domain networking environments, where an AIU is composed of the mission data, metadata, and policy. An AIU provides a mechanism to establish trust among deployed AIUs based on recombining shared secrets, authentication and verify users with a username, X.509 certificate, enclave information, and classification level. AIU achieves data protection through (1) splitting data into multiple information pieces using the Shamir's secret sharing algorithm, (2) encrypting each individual information piece using military-grade AES-256 encryption, and (3) randomizing the position of the encrypted data based on the unbiased and memory efficient in-place Fisher-Yates shuffle method. Therefore, it becomes virtually impossible for attackers to compromise data since attackers need to obtain all distributed information as well as the encryption key and the random seeds to properly arrange the data. In addition, since policy can be associated with data in the AIU, different user access and data control strategies can be included. The AIU technology can greatly enhance information assurance and security management in the bandwidth-limited and ad hoc net-centric environments. In addition, AIU technology can be applicable to general complex network domains and applications where distributed user authentication and data protection are necessary. AIU achieves fine-grain data access and user control, reducing the security risk significantly, simplifying the complexity of various security operations, and providing the high information assurance across different network domains.

Chow, Edward T.↗
NASA NTRS1971

The programming language HAL: A specification

HAL accomplishes three significant objectives: (1) increased readability, through the use of a natural two-dimensional mathematical format; (2) increased reliability, by providing for selective recognition of common data and subroutines, and by incorporating specific data-protect features; (3) real-time control facility, by including a comprehensive set of real-time control commands and signal conditions. Although HAL is designed primarily for programming on-board computers, it is general enough to meet nearly all the needs in the production, verification and support of aerospace, and other real-time applications.

Source record↗
NASA NTRS1973

Remote Sensing Center

The applications are reported of new remote sensing techniques for earth resources surveys and environmental monitoring. Applications discussed include: vegetation systems, environmental monitoring, and plant protection. Data processing systems are described.

Source record↗
NASA NTRS1980

The effects of receiver tracking phase error on the performance of the concatenated Reed-Solomon Viterbi channel coding system

In connection with attempts to achieve very low error probabilities, Odenwalder (1970) proposed a concatenated coding system using the Viterbi-decoded convolutional codes as the inner code and Reed-Solomon (RS) codes as the outer code. Analytical and experimental results are presented concerning the effects of the receiver tracking phase error on the performance of the concatenated RS/Viterbi channel coding system. On the basis of these results it is concluded that certain problems regarding communication operations on deep-space missions can be alleviated by employing the RS/Viterbi coding system. In one-way communication, an employment of RS/Viterbi coding will also provide greater data protection than the Viterbi-decoded convolutional-only coding system.

Liu, K. Y.↗
NASA NTRS1994

The Space Communications Protocol Standards Program

In the fall of 1992 NASA and the Department of Defense chartered a technical team to explore the possibility of developing a common set of space data communications standards for potential dual-use across the U.S. national space mission support infrastructure. The team focused on the data communications needs of those activities associated with on-lined control of civil and military aircraft. A two-pronged approach was adopted: a top-down survey of representative civil and military space data communications requirements was conducted; and a bottom-up analysis of available standard data communications protocols was performed. A striking intersection of civil and military space mission requirements emerged, and an equally striking consensus on the approach towards joint civil and military space protocol development was reached. The team concluded that wide segments of the U.S. civil and military space communities have common needs for: (1) an efficient file transfer protocol; (2) various flavors of underlying data transport service; (3) an optional data protection mechanism to assure end-to-end security of message exchange; and (4) an efficient internetworking protocol. These recommendations led to initiating a program to develop a suite of protocols based on these findings. This paper describes the current status of this program.

Jeffries, Alan↗
NASA NTRS1996

Is the bang worth the buck? A RAID performance study

Expecting a high data delivery rate as well as data protection, the Lister Hill National Center for Biomedical Communications procured a RAID system to house image files for image delivery applications. A study was undertaken to determine the configuration of the RAID system that would provide for the fastest retrieval of image files. Average retrieval times with single and with concurrent users were measured for several stripe widths and several numbers of disks for RAID levels 0, 0+1 and 5. These are compared to each other and to average retrieval times for non-RAID configurations of the same hardware. Although the study in ongoing, a few conclusions have emerged regarding the tradeoffs among the different configurations with respect to file retrieval speed and cost.

Hauser, Susan E.↗
NASA NTRS2008

Prediciting Solar Activity: Today, Tomorrow, Next Year

Fleets of satellites circle the Earth collecting science data, protecting astronauts, and relaying information. All of these satellites are sensitive at some level to space weather effects. Predictions of drag on LEO spacecraft are one of the most important. Launching a satellite with less fuel can mean a higher orbit, but unanticipated solar activity and increased drag can make that a Pyrrhic victory. Energetic events at the Sun can produce crippling radiation storms. Predicting those events that will affect our assets in space includes a solar prediction and how the radiation will propagate through the solar system. I will talk our need for solar activity predictions and anticipate how those predictions could be made more accurate in the future.

Pesnell, William Dean↗
NASA NTRS2011

Solar Cycle Prediction

Solar cycle predictions are needed to plan long-term space missions; just like weather predictions are needed to plan your next vacation. Fleets of satellites circle the Earth collecting many types of science data, protecting astronauts, and relaying information. All of these satellites are sensitive at some level to solar cycle effects. Predictions of drag on LEO spacecraft are one of the most important. Launching a satellite with less propellant can mean a higher orbit, but unanticipated solar activity and increased drag can make that a Pyrrhic victory. Energetic events at the Sun can produce crippling radiation storms that endanger all assets in space. Testing solar dynamo theories by quantitative predictions of what will happen in 5-20 years is the next arena for solar cycle predictions. I will describe the current state of solar cycle predictions and anticipate how those predictions could be made more accurate in the future.

Pesnell, William Dean↗
NASA NTRS2012

Solar Cycle Predictions

Solar cycle predictions are needed to plan long-term space missions; just like weather predictions are needed to plan the launch. Fleets of satellites circle the Earth collecting many types of science data, protecting astronauts, and relaying information. All of these satellites are sensitive at some level to solar cycle effects. Predictions of drag on LEO spacecraft are one of the most important. Launching a satellite with less propellant can mean a higher orbit, but unanticipated solar activity and increased drag can make that a Pyrrhic victory as you consume the reduced propellant load more rapidly. Energetic events at the Sun can produce crippling radiation storms that endanger all assets in space. Solar cycle predictions also anticipate the shortwave emissions that cause degradation of solar panels. Testing solar dynamo theories by quantitative predictions of what will happen in 5-20 years is the next arena for solar cycle predictions. A summary and analysis of 75 predictions of the amplitude of the upcoming Solar Cycle 24 is presented. The current state of solar cycle predictions and some anticipations how those predictions could be made more accurate in the future will be discussed.

Pesnell, William Dean↗
NASA NTRS2012

Mission Assurance Modeling and Simulation: A Cyber Security Roadmap

This paper proposes a cyber security modeling and simulation roadmap to enhance mission assurance governance and establish risk reduction processes within constrained budgets. The term mission assurance stems from risk management work by Carnegie Mellon's Software Engineering Institute in the late 19905. By 2010, the Defense Information Systems Agency revised its cyber strategy and established the Program Executive Officer-Mission Assurance. This highlights a shift from simply protecting data to balancing risk and begins a necessary dialogue to establish a cyber security roadmap. The Military Operations Research Society has recommended a cyber community of practice, recognizing there are too few professionals having both cyber and analytic experience. The authors characterize the limited body of knowledge in this symbiotic relationship. This paper identifies operational and research requirements for mission assurance M&S supporting defense and homeland security. M&S techniques are needed for enterprise oversight of cyber investments, test and evaluation, policy, training, and analysis.

Gendron, Gerald↗
NASA NTRS2013

High Altitude Supersonic Decelerator Test Vehicle

The Low Density Supersonic Decelerator (LDSD) project is tasked by NASA's Office of the Chief Technologist (OCT) to advance the state of the art in Mars entry and descent technology in order to allow for larger payloads to be delivered to Mars at higher altitudes with better accuracy. The project will develop a 33.5 m Do Supersonic Ringsail (SSRS) parachute, 6m attached torus, robotic class Supersonic Inflatable Aerodynamic Decelerator (SIAD-R), and an 8 m attached isotensoid, exploration class Supersonic Inflatable Aerodynamic Decelerator (SIAD-E). The SSRS and SIAD-R should be brought to TRL-6, while the SIAD-E should be brought to TRL-5. As part of the qualification and development program, LDSD must perform a Mach-scaled Supersonic Flight Dynamics Test (SFDT) in order to demonstrate successful free flight dynamic deployments at Mars equivalent altitude, of all three technologies. In order to perform these tests, LDSD must design and build a test vehicle to deliver all technologies to approximately 180,000 ft and Mach 4, deploy a SIAD, free fly to approximately Mach 2, deploy the SSRS, record high-speed and high-resolution imagery of both deployments, as well as record data from an instrumentation suite capable of characterizing the technology induced vehicle dynamics. The vehicle must also be recoverable after splashdown into the ocean under a nominal flight, while guaranteeing forensic data protection in an off nominal catastrophic failure of a test article that could result in a terminal velocity, tumbling water impact.

Cook, Brant T.↗
NASA NTRS2017

Knowledge Base for Distributed Spacecraft Mission Design Using the Trade-Space Analysis Tool for Constellations (TAT-C)

Opportunities for multi-point measurements, greater revisit frequency, failure robustness, and improved cost effectiveness motivate consideration of Distributed Spacecraft Missions (DSMs) for future Earth science missions. However, careful analysis is required to assess the distributed sensing capabilities of a constellation compared to more mature monolithic spacecraft while also considering other important dimensions such as cost and risk. The large combinatorial DSM design space limits existing mission analysis tools and exploration methods which emphasize monolithic design variables. The Trade-space Analysis Tool for Constellations (TAT-C) under development at Goddard seeks to enumerate and evaluate alternative mission architectures to minimize cost and maximize scientific return for pre-defined goals during pre-phase A analysis.Similar to other model-centric engineering efforts, efficient data management is a significant challenge for DSM mission analysis. In TAT-C, a Knowledge Base (KB) is envisioned as a cumulative central repository of information and meta-information about DSMs. Initial KB concepts store related data for reuse within or across mission analyses; however, over time, the KB is envisioned to be an important layer to coordinate actions of both human analysts and automated design agents to search a large design space for desirable mission alternatives. Preliminary KB research builds on a modern web technology stack to provide the following functionality: 1) storage of trade-space search requests which set requirements and constraints for DSM concepts, 2) storage of analysis results which quantify performance metrics for evaluated DSM concepts, 3) a RESTful application programming interface (API) for scripted access to data from TAT-C modules, 4) web-based graphical user interface (GUI) for manual access to underlying data, and 5) access control and management restrictions relevant to data protection and security. These efforts have culminated in a prototype KB used by the research team during TAT-C development to assess opportunities for future work.

Pattern Recognition↗
NASA NTRSDate not supplied

Next Steps: Laying the Groundwork for Bundle Protocol v7

Delay/Disruption Tolerant Networking (DTN) is a networking model and protocol suite that extends the terrestrial internet to the challenging communication environments of space. These environments are typically subject to frequent disruptions, which can cause delays or errors. DTN protects data transmission by wrapping data into bundles (similar to Internet Protocol packets), storing them until a connection can be established between two nodes (similar to terrestrial routers or computers), and forwarding them to their destinations. Bundle Protocol (BP) is responsible for generating those bundles and creates the transport layer of DTN, much like how Transmission Control Protocol (TCP) and User Datagram Protocol (UDP) create the transport layer of the Internet Protocol. BPv6 is the current, accepted version of the Bundle Protocol standard. However, recent missions and test implementations have revealed missing components and areas for improvement in the standard. Using lessons learned from NASA missions and gathering inspiration from the Internet Protocol, BPv7 is intended to be a more robust Bundle Protocol that improves upon its predecessor and increases the technology readiness level of the DTN architecture. The DTN Standard Interface Design team, a sub-team of the DTN Infusion Project at the Goddard Space Flight Center, worked to create a dictionary of terms for bundle components and functional decomposition of the protocol. These efforts aided in the standardization of BP interfaces, something missing from BPv6, and supported parallel network management and configuration work. This standardization will ultimately contribute to LunaNet (a lunar communications and navigation architecture that will bring networking, positioning, navigation, timing and science services to the Moon), the Solar System Internet (SSI), and expand crewed and uncrewed space exploration opportunities.

DTN↗
NASA NTRSDate not supplied

Next Steps: Laying the Groundwork for Bundle Protocol v7

Delay/Disruption Tolerant Networking (DTN) is a networking model and protocol suite that extends the terrestrial internet to the challenging communication environments of space. These environments are typically subject to frequent disruptions, which can cause delays or errors. DTN protects data transmission by wrapping data into bundles (similar to Internet Protocol packets), storing them until a connection can be established between two nodes (similar to terrestrial routers or computers), and forwarding them to their destinations. Bundle Protocol (BP) is responsible for generating those bundles and creates the transport layer of DTN, much like how Transmission Control Protocol (TCP) and User Datagram Protocol (UDP) create the transport layer of the Internet Protocol. BPv6 is the current, accepted version of the Bundle Protocol standard. However, recent missions and test implementations have revealed missing components and areas for improvement in the standard. Using lessons learned from NASA missions and gathering inspiration from the Internet Protocol, BPv7 is intended to be a more robust Bundle Protocol that improves upon its predecessor and increases the technology readiness level of the DTN architecture. The DTN Standard Interface Design team, a sub-team of the DTN Infusion Project at the Goddard Space Flight Center, worked to create a dictionary of terms for bundle components and functional decomposition of the protocol. These efforts aided in the standardization of BP interfaces, something missing from BPv6, and supported parallel network management and configuration work. This standardization will ultimately contribute to LunaNet (a lunar communications and navigation architecture that will bring networking, positioning, navigation, timing and science services to the Moon), the Solar System Internet (SSI), and expand crewed and uncrewed space exploration opportunities.

dtn↗
NASA NTRS1973

Application of ERTS-1 data to the protection and management of New Jersey's coastal environment

The author has identified the following significant results. Rates of erosion and accretion of the shoreline are being calculated for two test areas along the New Jersey coast. Measurements are made on aerial photographs taken over the last 20 years and processed by computer. The rates are presented in graphic form on an ERTS-1 base map at a scale of 1:125,000. These rates are being used to determine the effectiveness of various shore protection structures at preventing sand removal and encouraging sand accumulation. Information on maintenance and construction expenditures is being used to obtain a cost effectiveness ratio for various shore protection devices. The relationship of erosion rates, property value, and project cost are all criteria for selection of site type and extent of a shore protection structure. Compilation and evaluation of historical data will identify past decision making patterns. The effectiveness of these decisions with respect to erosion rates, property value, and project cost, can be used as an added criteria for future allocation of money and the selection of site and type of structure to be built.

Yunghans, R. S.↗