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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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NASA NTRS1988

Cosmic-ray-modified stellar winds. II - A perturbation approach

A perturbation method is developed to describe the modification of a stellar wind flow with termination shock by the Galactic cosmic rays. The perturbation parameter epsilon used in the analysis is the ratio of the galactic cosmic-ray pressure to the thermal gas pressure at a large distance from the star. The positive galactic cosmic-ray pressure gradient serves to brake the outflowing stellar wind gas, particularly just upstream of the termination shock of the wind. A one-fluid polytropic model is used to describe the thermal stellar wind gas, with the coupling between the cosmic rays and the thermal gas being determined by an average hydrodynamical diffusion coefficient kappa describing the scattering of cosmic rays by magnetohydrodynamic waves traveling in the background flow. The analysis takes into account cosmic-ray modifications of the critical point of the wind, the thermal gas entropy constants on both sides of the shock, and the fluid velocity profile.

Ko, C. M.↗
NASA NTRS1973

The isotopes of H and He in solar cosmic rays

The isotopic composition of H and He in solar cosmic rays was studied with the solar galactic cosmic ray experiment on the Orbiting Geophysical Observatory, OGO-6. Averaging over 20 days of data from seven flare events during 1969, the ratios He-3/-He-4 = 0.10 + or - 0.02, D/H (76) .0003 and T/H (76) .0001 in the 4 to 5 MeV/nucleon energy range were obtained. In addition, large variations were found in the relative abundance of He-3 from event of event, with a maximum ratio of He-3/He-4 = 0.26 + or - 0.08 observed on October 14 and 15, 1969. The relative abundance of He-3 and D during this event does not seem to be consistent with existing calculations of the nuclear interaction orgin of these isotopes.

Garrard, T. L.↗
NASA NTRS1983

The ISPM Mission - Science objectives and mission overview

The International Solar Polar Mission (ISPM) will, for the first time, allow exploration of the heliosphere within a few astronomical units of the sun over the full range of heliographic latitudes. The prime mission objective is to study, as a function of solar latitude, the properties of the interplanetary medium and solar corona. The scientific instrumentation is designed to explore, in the third heliospheric dimension, the properties of the solar wind, the sun/wind interface, the heliospheric magnetic field, solar radio bursts and plasma waves, solar X-rays, solar and galactic cosmic rays, and interplanetary/interstellar neutral gas and dust. ISPM will also detect cosmic gamma-ray bursts and search for gravitational waves. ISPM is a cooperative mission carried out jointly by ESA and NASA, to be launched in May 1986 and utilising a Jupiter gravity-assist to achieve a high-solar-latitude trajectory.

Wenzel, K.-P.↗
NASA NTRS1989

Ulysses - The first high-latitude heliospheric mission

The Ulysses mission will, for the first time, explore the heliosphere within a few astronomical units of the sun over the full range of heliographic latitudes, thereby providing the first characterization of the uncharted third dimension. Highly sophisticated scientific instrumentation carried on board the spacecraft is designed to measure the properties of the solar wind, the sun/wind interface, the heliospheric magnetic field, solar radio bursts and plasma waves, solar X-rays, solar and galactic cosmic rays, and interplanetary/interstellar neutral gas and dust. This collaborative ESA/NASA mission, scheduled for launch in October 1990, will use a Jupiter gravity-assist to achieve a trajectory extending to high solar latitudes /1,2/.

Wenzel, K.-P.↗
NASA NTRS1990

Rendezvous with a star

The spacecraft Ulysses carrying five European and four American instruments is described. The instruments are designed to investigate the properties of the solar wind, the sun-wind interface, the heliospheric magnetic field, solar radio burst and plasma waves, solar X-rays, solar and galactic cosmic rays, and gas and dust in interplanetary space. Ulysses is scheduled to be carried into orbit aboard the Space Shuttle in October 1990, when Jupiter's position relative to the earth is suitable for a minimum-energy trajectory. Once in orbit, a three-stage, solid-fuel vehicle known as the Inertial Upper Stage plus Payload Assist Module (Special), will then propel Ulysses on a 16-month journey to Jupiter. In February 1992, Ulysses is scheduled to fly past Jupiter toward its rendezvous with the sun. Ulysses will then head for a region of interplanetary space never before explored and is scheduled to have two solar encounters. Its official mission ends soon after September 1995.

Bennett, Gary L.↗
NASA NTRS1996

Measurement of proton production cross sections of (sup 10)Be and (sup 26)Al from elements found in lunar rocks

Cosmic rays penetrate the lunar surface and interact with the lunar rocks to produce both radionuclides and stable nuclides. Production depth profiles for long-lived radionuclides produce in lunar rocks are measured using Accelerator Mass Spectrometry (AMS). For a particular radionuclide these production depth profiles can be interpreted to give an estimate for the solar proton flux over a time period characterized by the half life of the radionuclide under study. This analysis is possible if and only if all the cross sections for the interactions of all cosmic ray particles with all elements found in lunar rocks are well known. In practice, the most important cross sections needed are the proton production cross sections, because 98% of solar cosmic rays and (similar to)87% of galactic cosmic rays are protons. The cross sections for the production of long-lived radionuclides were very difficult to measure before the development of AMS and only in recent years has significant progress been made in determining these essential cross sections. Oxygen and silicon are major constituents of lunar rocks. We have reported already C-14 production cross sections from O and Si for proton energies 25-500 MeV, and O(p,x)(sup 10)Be from 58 160 MeV[6]. Here we present new measurements for the cross sections O(p,x)Be-10,O(p,x)Be-7, Si(p,x)Be-7,Si(p,x)Al-26, and Si(p,x)Na-22 from approximately 30 - 500 MeV.

Sisterson, J. M.↗
NASA NTRS1990

Ulysses Launch

Ulysses is a joint mission between the United States National Aeronautics and Space Administration (NASA) and the European Space Agency (ESA) to explore the heliosphere over the full range of solar latitudes, especially in the polar regions. The goal of the Ulysses mission is to provide an accurate assessment of our total solar environment. This collaborative ESA/NASA mission will, for the first time, explore the heliosphere -- the region of space that is dominated by the Sun-- within a few astronomical units of the Sun over the full range of heliographic latitudes. The path followed by the spacecraft, using a Jupiter gravity-assist to achieve a trajectory extending to high solar latitudes, will enable the highly sophisticated scientific instruments on board to make measurements in the uncharted third dimension of the heliosphere. The Ulysses spacecraft will carry nine scientific instruments to measure the properties of the solar corona, the solar wind, the Sun/wind interface, the heliospheric magnetic field, solar radio bursts, plasma waves, solar X-rays, solar and galactic cosmic rays, and the interplanetary/interstellar neutral gas and dust. Scientists will take advantage of the enormous distance between the spacecraft and the Earth to perform astrophysical measurements and to search for gravitational waves. In conjunction with instrumentation on Earth-orbiting spacecraft, Ulysses will help to precisely locate the mysterious sources of cosmic gamma bursts. The results obtained will help to solve outstanding problems in solar and heliospheric physics, while undoubtedly revealing new and unanticipated phenomena.

Source record↗
NASA NTRS2011

Millisecond Pulsars at Gamma-Ray Energies: Fermi Detections and Implications

The Fermi Gamma-Ray Space Telescope has revolutionized the study of pulsar physics with the discovery of new populations of radio quiet and millisecond gamma-ray pulsars. The Fermi Large Area Telescope has so far discovered approx.20 new gamma-ray millisecond pulsars (MSPs) by both folding at periods of known radio MSPs or by detecting them as gamma-ray sources that are followed up by radio pulsar searches. The second method has resulted in a phenomenally successful synergy, with -30 new radio MSPs (to date) having been discovered at Fermi unidentified source locations and the gamma-ray pulsations having then been detected in a number of these using the radio timing solutions. Many of the newly discovered MSPs may be suitable for addition to the collection of very stable MSPs used for gravitational wave detection. Detection of such a large number of MSPs was surprising, given that most have relatively low spin-down luminosity and surface field strength. I will discuss their properties and the implications for pulsar particle acceleration and emission, as well as their potential contribution to gamma-ray backgrounds and Galactic cosmic rays.

Harding, Alice K.↗
NASA NTRS1988

Benchmark solutions for the galactic ion transport equations with spatial and energy coupling

In order to anticipate future space shielding requirements, NASA has initiated an effort to formulate computational methods to simulate radiation effects in space. As part of the program, numerical transport algorithms have been developed for the deterministic Boltzman equation describing galactic cosmic ray (GCR) interactions with matter. It thus becomes necessary to assess the accuracy of proposed deterministic algorithms. For this reason, analytical benchmark solutions to mathematically tractable galactic cosmic ray equations have recently been obtained. Even though these problems involve simplifying assumptions of the associated physics, they still contain the essential features of the basic transport processes. The solutions obtained are features of the basic transport processes. The solutions obtained are compared to results from numerical algorithms in order to ensure proper coding and to provide a measure of the accuracy of the numerical methods used in the algorithm. For the first time, mathematical methods have been applied to the galactic ion transport (GIT) equations in the straight ahead approximation with constant nuclear properties. The approach utilizes a Laplace transforms inversion yielding a closed form benchmark solution which is also computationally efficient.

Ganapol, Barry D.↗
NASA NTRS2001

The Energetic Trans-Iron Composition Experiment (ENTICE) on the Heavy Nuclei Explorer (HNX)

The ENTICE experiment is one of two instruments which make up the HNX mission. The experimental goal of ENTICE is to measure with high precision the elemental abundances of all nuclei with 10<=Z<=82. This will enable us to distinguish between possible injection mechanisms for the galactic cosmic ray accelerator such-as those dependent upon volatility or first ionization potential, and to study the mix of nucleosynthetic processes that contribute to the galactic cosmic ray source. The ENTICE experiment utilizes the dE/dx-C method of charge determination and consists of silicon dE/dx detectors, Cherenkov detectors with two different refractive indices, and a scintillating fiber hodoscope. The geometrical factor of the instrument is 8m2.sr. We will present a description of the instrument and its expected performance based on beam tests and a balloon flight of a prototype instrument.

Israel, M. H.↗
NASA NTRS2016

Space Radiation Research at NASA

The harmful effects of space radiation on astronauts is one of the most important limiting factors for human exploration of space beyond low Earth orbit, including a journey to Mars. This talk will present an overview of space radiation issues that arise throughout the solar system and will describe research efforts at NASA aimed at studying space radiation effects on astronauts, including the experimental program at the NASA Space Radiation Laboratory at Brookhaven National Laboratory. Recent work on galactic cosmic ray simulation at ground based accelerators will also be presented. The three major sources of space radiation, namely geomagnetically trapped particles, solar particle events and galactic cosmic rays will be discussed as well as recent discoveries of the harmful effects of space radiation on the human body. Some suggestions will also be given for developing a space radiation program in the Republic of Korea.

Norbury, John↗
NASA NTRS2003

The Status of Cross Section Measurements for Neutron-induced Reactions Needed for Cosmic Ray Studies

Cosmic ray interactions with lunar rocks and meteorites produce small amounts of radionuclides and stable isotopes. Advances in Accelerator Mass Spectrometry (AMS) allow production rates to be measured routinely in well-documented lunar rocks and meteorites. These measurements are analyzed using theoretical models to learn about the object itself and the history of the cosmic rays that fell on it. Good cross section measurements are essential input to the theoretical calculations. Most primary cosmic ray particles are protons so reliable cross sections for proton-induced reactions are essential. A cross section is deemed accurate if measurements made by different experimenters using different techniques result in consistent values. Most cross sections for proton induced reactions are now well measured. However, good cross section measurements for neutron-induced reactions are still needed. These cross sections are required to fully account for all galactic cosmic ray interactions at depth in an extraterrestrial object. When primary galactic cosmic ray (GCR) particles interact with an object many secondary neutrons are produced, which also initiate spallation reactions. Thus, the total GCR contribution to the overall cosmogenic nuclide archive has to include the contribution from the secondary neutron interactions. Few relevant cross section measurements have been reported for neutron-induced reactions at neutron energies greater than approximately 20 MeV. The status of the cross section measurements using quasi-monoenergetic neutron energies at iThemba LABS, South Africa and white neutron beams at Los Alamos Neutron Science Center (LANSCE), Los Alamos are reported here.

Sisterson, J. M.↗
NASA NTRS2010

NASA Self-Assessment of Space Radiation Research

Space exploration involves unavoidable exposures to high-energy galactic cosmic rays whose penetration power and associated secondary radiation makes radiation shielding ineffective and cost prohibitive. NASA recognizing the possible health dangers from cosmic rays notified the U.S. Congress as early as 1959 of the need for a dedicated heavy ion accelerator to study the largely unknown biological effects of galactic cosmic rays on astronauts. Information and scientific tools to study radiation health effects expanded over the new decades as NASA exploration programs to the moon and preparations for Mars exploration were carried out. In the 1970 s through the early 1990 s a more than 3-fold increase over earlier estimates of fatal cancer risks from gamma-rays, and new knowledge of the biological dangers of high LET radiation were obtained. Other research has increased concern for degenerative risks to the central nervous system and other tissues at lower doses compared to earlier estimates. In 1996 a review by the National Academy of Sciences Space Science Board re-iterated the need for a dedicated ground-based accelerator facility capable of providing up to 2000 research hours per year to reduce uncertainties in risks projections and develop effective mitigation measures. In 1998 NASA appropriated funds for construction of a dedicated research facility and the NASA Space Radiation Laboratory (NSRL) opened for research in October of 2003. This year marks the 8th year of NSRL research were about 1000 research hours per year have been utilized. In anticipation of the approaching ten year milestone, funded investigators and selected others are invited to participate in a critical self-assessment of NSRL research progress towards NASA s goals in space radiation research. A Blue and Red Team Assessment format has been integrated into meeting posters and special plenary sessions to allow for a critical debate on the progress of the research and major gaps areas. Blue teams will highlight progress and important new knowledge gained. Red teams will challenge the Blue teams on proposed highlights and point to Gaps not considered. We will review the current space radiation Risks and Gaps under investigation at NASA, critical data sets and research highlights anticipated, and possible goals for future research at NSRL.

Cucinotta, Francis A.↗
DOE OSTI2022

Gas and Cosmic-Ray Properties in the MBM 53, 54, and 55 Molecular Clouds and the Pegasus Loops Revealed by H i Line Profiles, Dust, and Gamma-Ray Data

In studying the interstellar medium (ISM) and Galactic cosmic rays (CRs), uncertainty of the interstellar gas density has always been an issue. To overcome this difficulty, we used a component decomposition of the 21 cm H i emission line and used the resulting gas maps in an analysis of γ-ray data obtained by the Fermi Large Area Telescope (LAT) for the MBM 53, 54, and 55 molecular clouds and the Pegasus loop. We decomposed the ISM gas into intermediate-velocity clouds, narrow-line and optically thick H i, broad-line and optically thin H i, CO-bright H 2 , and CO-dark H 2 using detailed correlations with the H i line profiles from the HI4PI survey, the Planck dust-emission model, and the Fermi-LAT γ-ray data. We found the fractions of the optical depth correction to the H i column density and CO-dark H 2 to be nearly equal. We fitted the CR spectra directly measured at/near the Earth and the measured γ-ray emissivity spectrum simultaneously. We obtained a spectral break in the interstellar proton spectrum at ~7 GeV, and found that the γ-ray emissivity normalization agrees with the AMS-02 proton spectrum within 10%, relaxing the tension with the CR spectra previously claimed.

79 ASTRONOMY AND ASTROPHYSICS↗
NASA NTRS1974

The distribution of cosmic rays in the galaxy and their dynamics as deduced from recent gamma-ray observations

Recent data from SAS-2 on the galactic gamma ray line flux as a function of longitude reveal a broad maximum in the gamma ray intensity in the region absolute value of l approximately smaller than 30 deg. These data imply that the low energy galactic cosmic ray flux varies with galactocentric distance and is about an order of magnitude higher than the local value in a toroidal region between 4 and 5 kpc from the galactic center. This enhancement can be plausibly accounted for by first order Fermi acceleration, compression and trapping of cosmic rays consistent with present ideas of galactic dynamics and galactic structure theory. Calculations indicate that cosmic rays in the 4 to 5 kpc region are trapped and accelerated over a mean time of the order of a few million years or about 2 to 4 times the assumed trapping time in the solar region of the galaxy.

Puget, J. L.↗
NASA NTRS1978

Gamma ray astronomy and the origin of the light nuclei

Nuclear reactions induced by the collisions of the protons and alphas of the galactic cosmic ray with heavy nuclei of the interstellar gas are responsible for the continuous production of the light elements lithium, beryllium, and boron in the galaxy. To better than one order of magnitude, the observed ratios of these abundances to hydrogen abundance and the nuclidic abundance ratios between themselves are accounted for by simply considering the effect of fast protons and alphas with a flux and an energy spectrum as observed in galactic cosmic rays, for a period comparable with the life of our galaxy. The role of gamma ray astronomy in solving problems that occur when accurate agreement is sought with increasingly accurate data is discussed.

Reeves, H.↗
NASA NTRS1981

Relativistic cosmic rays and corotating interaction regions

The relationships between relativistic galactic cosmic ray intensity variations and corotating interaction regions (CIRs) are examined. Times of CIRs overtaking the earth as indicated by Pioneer 10 and 11 plasma and field observations are compared with nucleonic intensities recorded at the Thule and McMurdo polar stations in a superposed epoch analysis, with the centers of the CIR as zero days. Results indicate a decrease in intensity around the zero days, as well as a maximum around the ninth day and a general upward trend from days -13 to 13. Further examination reveals the observed features to be present only for those CIR- associated streams in which a neutral sheet is embedded. In contrast, superposed epoch analysis of the geomagnetic Ap index with respect to CIR epochs reveals CIRs both with and without neutral sheets to produce geomagnetic storms, although the peak increase in Ap index is greater for neutral-sheet-associated CIRs. Results suggest that the CIRs modulate high-energy particle intensities by means of drifts related to neutral sheets, although diffusion effects cannot yet be ruled out.

Duggal, S. P.↗