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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 433 records · Page 24
All sourcesNASA NTRSDOE OSTI
NASA NTRS2008

Use of Sonification for Analysis and Detection of Plasma Bubbles at 21 MHz

This research explores sonification as a useful tool for space science data exploration. Our interest lies in basic scientific analysis of plasmas of the ionosphere, of interplanetary space and of the interstellar medium. These plasmas all contain irregularities. Propagation of electromagnetic waves, like optical or radio waves, through a medium with random fluctuations in refractive index results in amplitude and phase fluctuations (Scheuer 1968). These variations may be displayed via sonification, using changes in sounds to represent the data variations. This is particularly useful extending science to the visually-impaired. The xSonify Java-based tool was developed to explore sonification techniques and its value for general science analysis and also assistive technology.

Wanda, Diaz↗
NASA NTRS2001

Space radiation dosimetry in low-Earth orbit and beyond

Space radiation dosimetry presents one of the greatest challenges in the discipline of radiation protection. This is a result of both the highly complex nature of the radiation fields encountered in low-Earth orbit (LEO) and interplanetary space and of the constraints imposed by spaceflight on instrument design. This paper reviews the sources and composition of the space radiation environment in LEO as well as beyond the Earth's magnetosphere. A review of much of the dosimetric data that have been gathered over the last four decades of human space flight is presented. The different factors affecting the radiation exposures of astronauts and cosmonauts aboard the International Space Station (ISS) are emphasized. Measurements made aboard the Mir Orbital Station have highlighted the importance of both secondary particle production within the structure of spacecraft and the effect of shielding on both crew dose and dose equivalent. Roughly half the dose on ISS is expected to come from trapped protons and half from galactic cosmic rays (GCRs). The dearth of neutron measurements aboard LEO spacecraft and the difficulty inherent in making such measurements have led to large uncertainties in estimates of the neutron contribution to total dose equivalent. Except for a limited number of measurements made aboard the Apollo lunar missions, no crew dosimetry has been conducted beyond the Earth's magnetosphere. At the present time we are forced to rely on model-based estimates of crew dose and dose equivalent when planning for interplanetary missions, such as a mission to Mars. While space crews in LEO are unlikely to exceed the exposure limits recommended by such groups as the NCRP, dose equivalents of the same order as the recommended limits are likely over the course of a human mission to Mars. c2001 Elsevier Science B.V. All rights reserved.

short duration↗
NASA NTRS1985

Acceleration of energetic particles

Acceleration of some particles from the background plasma to highly superthermal energies is a common feature of collisionless shocks in interplanetary space. The complete in situ measurements of bulk flows, thermal plasma, electromagnetic waves and energetic particles available for interplanetary shocks both suggest and test the models of shock acceleration in the solar system and the rest of the universe. This tutorial will review the present state of shock acceleration theory. Scatter-free acceleration by grad B drift in the plasma electric field E = -V x B/c, and diffusive acceleration resulting from scattering by Alfven waves in the plasma on both sides of the shock are discussed. The diffusive theory in simple steady state gives power-law spectra, but also shows the effects of time-dependent shocks and injection rates, escape and other losses, the self-consistent Alfven wave spectra, and plasma flow fields affected by diffusive energetic particle acceleration.

Forman, M. A.↗
NASA NTRS1988

Data Transport Subsystem - The SFOC glue

The design and operation of the Data Transport Subsystem (DTS) for the JPL Space Flight Operation Center (SFOC) are described. The SFOC is the ground data system under development to serve interplanetary space probes; in addition to the DTS, it comprises a ground interface facility, a telemetry-input subsystem, data monitor and display facilities, and a digital TV system. DTS links the other subsystems via an ISO OSI presentation layer and an LAN. Here, particular attention is given to the DTS services and service modes (virtual circuit, datagram, and broadcast), the DTS software architecture, the logical-name server, the role of the integrated AI library, and SFOC as a distributed system.

Parr, Stephen J.↗
NASA NTRS1977

Ice in space: An experimental and theoretical investigation

Basic knowledge is provided on the behavior of ice and ice particles under a wide variety of conditions including those of interplanetary space. This information and, in particular, the lifetime of ice particles as a function of solar distance is an absolute requirement for a proper interpretation of photometric profiles in comets. Because fundamental properties of ice and ice particles are developed in this report, the applicability of this information extends beyond the realm of comets into any area where volatile particles exist, be it in space or in the earth's atmosphere.

Patashnick, H.↗
NASA NTRS1977

Mariner-Jupiter-Saturn Low Energy Charged Particle Experiment

The Low Energy Charged Particle Experiment will be launched on the Mariner-Jupiter-Saturn spacecraft in August 1977. The experiment has been designed to perform particle measurements in the intense radiation belts of the Jovian and Saturnian environments, and to provide detailed spectral analysis of both solar and galactic particles in interplanetary space. A single instrument uses 23 solid-state detectors configured in two distinct detector subsystems: one optimized for interplanetary and interstellar measurements, the other for specific particle species, energies, and intensities expected near the planets.

Peletier, D. P.↗
NASA NTRS1979

Gamma-ray burst observations from Helios-2

Observations of five gamma-ray bursts made with the solar orbiter Helios-2 are reported. Wavefront timing from Helios-2, at distances of up to 1.98 AU, to Vela-5A and -6A, in Earth orbit, provides source location bands as narrow as 2 arc minutes, although several degrees in length. The burst intensities and time profiles measured in interplanetary space by Helios-2 are the same as those observed near the earth, ruling out a narrow-beam interplanetary origin model. Also, the source direction bands for these events are inconsistent with the directions of all known celestial X-ray objects, X-ray bursters and high-energy gamma-ray source regions. The gamma-ray burst source objects therefore appear to form a distinct class from all lower energy X-ray or higher energy gamma ray emitters.

Cline, T. L.↗
NASA NTRS1979

Gamma-ray burst observations from Helios 2

Observations of five gamma-ray bursts made with the solar orbiter Helios 2 are reported. Wavefront timing from Helios 2, at distances of up to 1.98 AU, to Vela 5A and 6A, in earth orbit, provides source location bands as narrow as 2 arcmin, although several degrees in length. The burst intensities and time profiles measured in interplanetary space by Helios 2 are the same as those observed near the earth, ruling out a narrow-beam interplanetary origin model. Also, the source direction bands for these events are inconsistent with the directions of all known celestial X-ray objects, X-ray bursters, and high-energy gamma-ray source regions. The gamma-ray burst source objects therefore appear to form a class distinct from all lower-energy X-ray or higher energy gamma-ray emitters.

Cline, T. L.↗
NASA NTRS1991

The NASA Radiation Health Program

The Space Radiation Health Program (SRHP) is defined in terms of motivation and methodology with specific reference given to the impacts of HZE particles and solar energetic particles. The biological hazards are mentioned that can be associated with the two particle types and ionizing radiation in general. The lack of data on the impact of such radiation and effective shielding countermeasures is identified as the primary motivation for worst-case assumptions. However, the resulting shielding designs can potentially overestimate the thickness by a factor of 10 and add unnecessarily to vehicle take-off mass. A space-based validation system is proposed to complement ground-based investigations of the effects of ionizing radiation in interplanetary space. The Lifesat satellite is proposed as a part of the SRHP effort to determine the requirements for protection and future shielding specifications.

Schimmerling, Walter↗
NASA NTRS2012

Highlights of Space Weather Services/Capabilities at NASA/GSFC Space Weather Center

The importance of space weather has been recognized world-wide. Our society depends increasingly on technological infrastructure, including the power grid as well as satellites used for communication and navigation. Such technologies, however, are vulnerable to space weather effects caused by the Sun's variability. NASA GSFC's Space Weather Center (SWC) (http://science.gsfc.nasa.gov//674/swx services/swx services.html) has developed space weather products/capabilities/services that not only respond to NASA's needs but also address broader interests by leveraging the latest scientific research results and state-of-the-art models hosted at the Community Coordinated Modeling Center (CCMC: http://ccmc.gsfc.nasa.gov). By combining forefront space weather science and models, employing an innovative and configurable dissemination system (iSWA.gsfc.nasa.gov), taking advantage of scientific expertise both in-house and from the broader community as well as fostering and actively participating in multilateral collaborations both nationally and internationally, NASA/GSFC space weather Center, as a sibling organization to CCMC, is poised to address NASA's space weather needs (and needs of various partners) and to help enhancing space weather forecasting capabilities collaboratively. With a large number of state-of-the-art physics-based models running in real-time covering the whole space weather domain, it offers predictive capabilities and a comprehensive view of space weather events throughout the solar system. In this paper, we will provide some highlights of our service products/capabilities. In particular, we will take the 23 January and the 27 January space weather events as examples to illustrate how we can use the iSWA system to track them in the interplanetary space and forecast their impacts.

Fok, Mei-Ching↗
NASA NTRS2017

Cloudy with a Chance of Solar Flares: The Sun as a Natural Hazard

Space weather is a naturally occurring phenomenon that represents a quantifiable risk to space- and ground-based infrastructure as well as society at large. Space weather hazards include permanent and correctable faults in computer systems, Global Positioning System (GPS) and high-frequency communication disturbances, increased airline passenger and astronaut radiation exposure, and electric grid disruption. From the National Space Weather Strategy, published by the Office of Science and Technology Policy in October 2015, space weather refers to the dynamic conditions of the space environment that arise from emissions from the Sun, which include solar flares, solar energetic particles, and coronal mass ejections. These emissions can interact with Earth and its surrounding space, including the Earth's magnetic field, potentially disrupting technologies and infrastructures. Space weather is measured using a range of space- and ground-based platforms that directly monitor the Sun, the Earth's magnetic field, the conditions in interplanetary space and impacts at Earth's surface, like neutron ground-level enhancement. The NASA Goddard Space Flight Center's Space Weather Research Center and their international collaborators in government, industry, and academia are working towards improved techniques for predicting space weather as part of the strategy and action plan to better quantify and mitigate space weather hazards. In addition to accurately measuring and predicting space weather, we also need to continue developing more advanced techniques for evaluating space weather impacts on space- and ground-based infrastructure. Within the Earth's atmosphere, elevated neutron flux driven by atmosphere-particle interactions from space weather is a primary risk source. Ground-based neutron sources form an essential foundation for quantifying space weather impacts in a variety of systems.

neutron flux↗
NASA NTRS2015

Planetary CubeSats Come of Age

Jet Propulsion Laboratory initiatives in developing and formulating planetary CubeSats are described. Six flight systems already complete or underway now at JPL for missions to interplanetary space, the Moon, a near-Earth asteroid, and Mars are described at the subsystem level. Key differences between interplanetary nanospacecraft and LEO CubeSats are explained, as well as JPL's adaptation of vendor components and development of system solutions to meet planetary-mission needs. Feasible technology-demonstration and science measurement objectives are described for multiple modes of planetary mission implementation. Seven planetary-science demonstration mission concepts, already proposed to NASA by Discovery-2014 PIs partnered with JPL, are described for investigations at Sun-Earth L5, Venus, NEA 1999 FG3, comet Tempel 2, Phobos, main-belt asteroid 24 Themis, and metal asteroid 16 Psyche. The JPL staff and facilities resources available to PIs for analysis, design, and development of planetary nanospacecraft are catalogued.

TDO↗
NASA NTRS1993

The solar flare myth

Many years of research have demonstrated that large, nonrecurrent geomagnetic storms, shock wave disturbances in the solar wind, and energetic particle events in interplanetary space often occur in close association with large solar flares. This result has led to a pradigm of cause and effect - that large solar flares are the fundamental cause of these events in the near-Earth space environmemt. This paradigm, which I call 'the solar flare myth,' dominates the popular perception of the relationship between solar activity and interplanetary and geomagnetic events and has provided much of the pragmatic rationale for the study of the solar flare phenomenon. Yet there is good evidence that this paradigm is wrong and that flares do not generally play a central role in producing major transient disturbances in the near-Earth space environment. In this paper I outline a different paradigm of cause and effect that removes solar flares from their central position in the chain of events leading from the Sun to near-Earth space. Instead, this central role is given to events known as coronal mass ejections.

Gosling, J. T.↗
NASA NTRS1972

Operating executive for the DSIF tracking subsystem software

The advanced engineering model of the DSIF tracking subsystem (DTS) is being developed by the Deep Space Instrumentation Facility. The DTS will provide effective and reliable tracking and data acquisition support for the complex planetary and interplanetary space flight missions planned for the 1970's. The nucleus of the subsystem is a Honeywell H832 digital computer. The design and capabilities of the real-time operating executive software are described.

Poulson, P. L.↗
NASA NTRS1974

A study of dynamical behavior of space environment

Studies have covered a wide range of problems in the space environment, such as the problems of the dynamical behavior of the thermosphere, hydromagnetic wave propagation in the ionosphere, and interplanetary space environment. The theories used to analyze these problems range from a continuum theory of magnetohydrodynamics to the kinetic theory of free molecular flow. This is because the problems encountered covered the entire range of the Knudsen number (i.e., the ratio of mean free path to the characteristic length). Significant results are summarized.

Wu, S. T.↗