SCIENTIFIC AND TECHNICAL AEROSPACE REPORTS
A Biweekly Publication of the National Aeronautics and Space Administration
VOLUME 44, ISSUE 12 - JUNE 20, 2006
90 ASTROPHYSICS
Includes cosmology; celestial mechanics; space plasmas; and interstellar and interplanetary gases and dust.
20060013647 National Space Science and Technology Center, Huntsville, AL, USA
3-D RPIC Smulations of Relativistic Jets: Particle Acceleration, Magnetic Field Generation, and Emission
Nishikawa, K.-I.; [2006]; 1 pp.; In English; 6th International Conference on High Energy Laboratory of Astrophysics, 11-14 Mar. 2006, Houston, TX, USA; No Copyright; Avail.: Other Sources; Abstract Only
Nonthermal radiation observed from astrophysical systems containing (relativistic) jets and shocks, e.g., supernova remnants, active galactic nuclei (AGNs), gamma-ray bursts (GRBs), and Galactic microquasar systems usually have power-law emission spectra. Fermi acceleration is the mechanism usually assumed for the acceleration of particles in astrophysical environments. Recent PIC simulations using injected relativistic electron-ion (electro-positron) jets show that acceleration occurs within the downstream jet, rather than by the scattering of particles back and forth across the shock as in Fermi acceleration. Shock acceleration is a ubiquitous phenomenon in astrophysical plasmas. Plasma waves and their associated instabilities (e.g., the Buneman instability, other two-streaming instability, and theWeibel instability) created in the .shocks are responsible for particle (electron, positron, and ion) acceleration. The simulation results show that the Weibel instability is responsible for generating and amplifying highly nonuniform, small-scale magnetic fields. These magnetic fields contribute to the electron's transverse deflection behind the jet head. The 'jitter' radiation from deflected electrons has different properties than synchrotron radiation which is calculated in a uniform magnetic field. This jitter radiation may be important to understanding the complex time evolution and/or spectral structure in gamma-ray bursts, relativistic jets, and supernova remnants. We will review recent PIC simulations which show particle acceleration in jets. Author
Particle Acceleration; Magnetic Fields; Emission Spectra; Field Emission; Gamma Ray Bursts; Active Galactic Nuclei; Quasars; Relativistic Particles
20060014028 Jet Propulsion Lab., California Inst. of Tech., Pasadena, CA, USA.
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Using the Moon and Mars as Giant Detectors for Strange Quark Nuggets
Chui, Talso; Penanen, Konstantin; Strayer, Don; Banerdt, Bruce; Tepliz, Vigdor; Herrin, Eugene; Proceedings of the 2004 NASA/JPL Workshop on Physics for Planetary Exploration; [2004]; In English; See also 20060014017; No Copyright; Abstract Only; Available from CASI on CD-ROM only as part of the entire parent document
On the Earth, the detectability of small seismic signals is limited by pervasive seismic background noise, caused primarily by interactions of the atmosphere and oceans with the solid surface. Mars, with a very thin atmosphere and no ocean is expected to have a noise level at least an order of magnitude lower than the Earth, and the airless Moon is even quieter still. These pristine low-vibration environments are ideal for searching for nuggets of 'strange quark matter.' Strange quark matter was postulated by EdwardWitten [Phys. Rev. D30, 272, 1984] as the lowest possible energy state of matter. It would be made of up, down, and strange quarks, instead of protons and neutrons made only of up and down quarks. It would have nuclear densities, and hence be difficult to detect. Micron-sized nuggets would weigh in the ton range. As suggested by de Rujula and Glashow [Nature 312 (5996): 734, 1984], a massive strange quark nugget can generate a trail of seismic waves, as it traverses a celestial body. We discuss the mission concept for deploying a network of sensitive seismometers on Mars and on the Moon for such a search. Author
Moon; Mars (Planet); Signal Detection; Quarks; Seismic Waves; Seismographs; Sensitivity; Solid Surfaces; Noise Intensity
20060014050 Brown Univ., Providence, RI, USA
Magnetic Levitation Based Martian and Lunar Gravity Simulator
Valles, J. M.; Maris, H. J.; Seidel, G. M.; Tang, J.; Yao, W.; Proceedings of the 2004 NASA/JPL Workshop on Physics for Planetary Exploration; [2004]; In English; See also 20060014017; No Copyright; Abstract Only; Available from CASI on CD-ROM only as part of the entire parent document A session on magnetic levitation began with a report by Jim Valles of Brown University on simulation of Martian and Lunar gravity. A magnetic ground-based device would be extremely helpful to studies of the impact reduced gravity has on living things, and the effort to mitigate any harmful effects. The ability to simulate microgravity on the ground would also be extremely useful as a substitute for the ISS, enabling investigations formerly planned for that facility to be carried out on Earth. Valles emphasized the cost-effectiveness of the project compared to experiments in space that use rotation to introduce a controlled level of gravity. In addition, he pointed out that magnetic levitation on Earth has the advantage of long experimental times with a controlled laboratory environment. Charles Rosenblatt of Case Western Reserve University spoke on temporal measurements of surfactant squeeze-out from a surface, using magnetically-levitated liquid bridges. He said that magnetic levitation has numerous applications in studies of fluids, soft and 'hard' condensed matter physics, and biophysics, and spoke of its application for soil wetting in future Martian agriculture. Rosenblatt pointed out that magnetic levitation makes it possible to adjust gravity to any desired value. Yuanming Liu of the Jet Propulsion Laboratory discussed JPL s magnetic low-gravity simulator. He said the group has been able to levitate liquid helium, a difficult substance to levitate. For exploration-related study of fluid systems, he said JPL proposes to construct a new facility using a large-bore (approx.3-inch) superconducting magnet in a superfluid dewar. Author
Lunar Gravity Simulator; Magnetic Suspension; Levitation; Liquid Helium; Lunar Gravitation; Surfactants; Microgravity; Condensed Matter Physics
20060014066 NASA Goddard Space Flight Center, Greenbelt, MD, USA
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Seismic Search for Strange Quark Matter
Teplitz, Vigdor; Proceedings of the 2004 NASA/JPLWorkshop on Physics for Planetary Exploration; [2004]; In English; See also 20060014017; No Copyright; Abstract Only; Available from CASI on CD-ROM only as part of the entire parent document
Two decades ago, Witten suggested that the ground state of matter might be material of nuclear density made from up, down and strange quarks. Since then, much effort has gone into exploring astrophysical and other implications of this possibility. For example, neutron stars would almost certainly be strange quark stars; dark matter might be strange quark matter. Searches for stable strange quark matter have been made in various mass ranges, with negative, but not conclusive results. Recently, we [D. Anderson, E. Herrin, V. Teplitz, and I. Tibuleac, Bull. Seis. Soc. of Am. 93, 2363 (2003)] reported a positive result for passage through the Earth of a multi-ton 'nugget' of nuclear density in a search of about a million seismic reports, to the U.S. Geological Survey for the years 1990-93, not associated with known Earthquakes. I will present the evidence (timing of first signals to the 9 stations involved, first signal directions, and unique waveform characteristics) for our conclusion and discuss potential improvements that could be obtained from exploiting the seismologically quieter environments of the moon and Mars. Author
Dark Matter; Ground State; Matter (Physics); Geological Surveys; Astrophysics; Quarks
20060014612 Air Force Research Lab., Edwards AFB, CA USA
Computer Programs for Solar Concentrator Focus Control (PREPRINT)
Beasley, Joseph N; Holmes, Michael R; Sep 7, 2005; 16 pp.; In English Contract(s)/Grant(s): Proj-1011 Report No.(s): AD-A442594; AFRL-PR-ED-TP-205-342; No Copyright; ONLINE: http://hdl.handle.net/100.2/ADA442594; Avail.: CASI: A03, Hardcopy
This paper describes two methods for imaging an absorber used as a new sensor in determining the location of the focal spot for a solar concentrator. The absorber is used as a sensor in both methods, but in slightly different ways. The first method developed is an optimization method inspired by Shack-Hartmann wave front sensing. This optimization utilizes masking and a correlation calculation to determine the error from the current image of the focal spot and the ideal or designed position of the focal spot. The second method still uses the absorber as a sensor but calculates area moments of the reflected sunlight on the tubing to calculate the current location of the focal spot. DTIC
Computer Programs; Solar Collectors
20060014852 Air Force Research Lab., Hanscom AFB, MA USA
Characteristic Times of Gradual Solar Energetic Particle Events and Their Dependence on Associated Coronal Mass Ejection Properties
Kahler, Stephen W; Aug 1, 2005; 10 pp.; In English Contract(s)/Grant(s): Proj-2311 Report No.(s): AD-A442766; AFRL-VS-HA-TR-2005-1197; No Copyright; ONLINE: http://hdl.handle.net/100.2/ADA442766; Avail.: CASI: A02, Hardcopy
We use 20 MeV proton intensities from the EPACT instrument on Wind and coronal mass ejections (CMEs) from the LASCO coronagraph on SOHO observed during 1998-2002 to statistically determine three characteristic times of gradual solar energetic particle (SEP) events as functions of solar source longitude: (1) T(sub 0), the time from associated CME launch to SEP onset at 1 AU, (2) T(sub R), the rise time from SEP onset to the time when the SEP intensity is a factor of 2 below peak intensity, and (3) T(sub D), the duration over which the SEP intensity is within a factor of 2 of the peak intensity. Those SEP event times are compared with associated CME speeds, accelerations, and widths to determine whether and how the SEP event times may depend on the formation and dynamics of coronal/interplanetary shocks driven by the CMEs. Solar source longitudinal variations are clearly present in the SEP times, but T(sub R)and T(sub D) are significantly correlated with CME speeds only for SEP events in the best-connected longitude range. No significant correlations between the SEP times and CME accelerations are found except for T(sub D) in one longitude range, but there is a weak correlation of T(sub R) and T(sub D) with CME widths. We also find no correlation of any SEP times with the solar wind O(exp +6)/O(exp +7) values, suggesting no dependence on solar wind stream type. The SEP times of the small subset of events occurring in interplanetary CMEs may be slightly shorter than those of all events. DTIC
Coronal Mass Ejection; Energetic Particles; Solar Corpuscular Radiation; Solar Flares; Solar Storms; Solar Wind
20060014868 Air Force Research Lab., Hanscom AFB, MA USA
Comparison of Recent Measurements of Atmospheric Optical Turbulence
Jumper, George Y; Vernin, Jean; Azouit, Max; Trinquet, Herve; Jun 2005; 13 pp.; In English Contract(s)/Grant(s): Proj-1010 Report No.(s): AD-A442791; AFRL-VS-HA-TR-2005-1124; No Copyright; ONLINE: http://hdl.handle.net/100.2/ADA442791; Avail.: CASI: A03, Hardcopy
A recent multi-sensor optical turbulence measurement campaign in the Haute-Provence region of France provided a unique comparison of optical turbulence sensors. Thermosondes from both the US and France were used. measuring temperature structure functions for 30 com, 95 cm, and 1 meter. In addition, turbulence was measured using a Generalized Scidar (GS) mounted on a 1.93 m diameter telescope at 1'Observatoire de Haute-Provence (OH). The GS measures optical turbulence strength and altitude from the scintillation of binary stars observed over periods from several minutes to several hours. The GS has 300 m vertical resolution from 25 km down to nearly the opt of the telescope. This paper describes the instruments and compares their performance. While the instruments did not yield identical results, agreement was reasonable. Jean VerninT, Max Azouit%, and Herve' Trinquet% DTIC
Atmospheric Circulation; Atmospheric Turbulence; Refractivity
20060015397 Boston Coll., Chestnut Hill, MA USA
Very High Altitude Aurora Observations with the Solar Mass Ejection Imager
Mizuno, D R; Buffington, A; Cooke, M P; Eyles, C J; Hick, P P; Holladay, P E; Jackson, B V; Johnston, J C; Kuchar, T A; Mozer, J B; Jul 29, 2005; 19 pp.; In English Contract(s)/Grant(s): Proj-2822 Report No.(s): AD-A443217; No Copyright; ONLINE: http://hdl.handle.net/100.2/ADA443217; Avail.: CASI: A03, Hardcopy
The Solar Mass Ejection Imager (SMEI) is a sensitive scanning instrument mounted on the Coriolis satellite that assembles an approximately all-sky image of the heliosphere in red-biased visible light once per orbit. Its lines of sight pass obliquely through the topside ionosphere and magnetosphere. We present serendipitous observations of a visual phenomenon detected at high altitudes (greater than or equal to 840 km) over the auroral zones and polar caps. The phenomenon is observed in two basic forms. The first, and more common, are periods of brief (1-3 min), nearly uniform illumination of the imager's field of view, which we interpret as transits of the satellite through a luminous medium. The second appear as localized filamentary structures, which we interpret as columns of luminous material, viewed from a distance, possibly extending to visible altitudes of 2000 km or higher. More than 1000 occurrences of these phenomena were recorded during the first full year of operations. These observations are well correlated in brightness and frequency with periods of enhanced geomagnetic activity. DTIC
Auroras; Coronal Mass Ejection; Ejection; High Altitude; Satellite Imagery; Stellar Mass
20060015427 Air Force Research Lab., Hanscom AFB, MA USA
Effects of Solar UV on Spacecraft Charging in Sunlight
Lai, Shu T; Tautz, Maurice; Tobiska, Kent; Jan 9, 2006; 6 pp.; In English Report No.(s): AD-A443268; AFRL-VS-HA-TR-2006-1022; No Copyright; ONLINE: http://hdl.handle.net/100.2/ADA443268; Avail.: CASI: A02, Hardcopy
Spacecraft surface charging is determined by the balance of currents. Photoelectron currents from spacecraft surfaces greatly exceed the ambient electron or ion currents and therefore are often of prime importance for charging in sunlight. The authors present a brief overview of several aspects of spacecraft charging in sunlight. For a conducting spacecraft at geosynchronous altitudes, charging in sunlight is usually up to a few positive volts only. If the spacecraft is in areas where the solar ultraviolet radiation is strong and the ambient electron density is low, the spacecraft can charge to a few tens of positive volts. For a non-conducting spacecraft at geosynchronous altitudes, the dark side can charge to hundreds or thousands of negative volts as a result of the collection of ambient electrons. There exists a critical electron temperature governing the onset of negative voltage charging. The sunlit side initially tends to charge to low positive volts. The high negative voltage of the dark side may wrap around the sunlit side forming a potential barrier blocking the photoelectrons emitted from the sunlit surfaces. As a result, the sunlit side may also charge to negative voltages. The critical temperature for this differential charging to occur is approximately the same as for eclipse charging. Depending on the spin axis with respect to the sun direction, monopole-dipole or monopole-quadrupole potential distributions may occur. For spacecraft with high surface reflectance, the photons do not deposit enough energy to generate photoelectrons. As a result, the surface can charge to high negative voltages in sunlight without invoking differential charging. In this case, the critical temperature is changed, depending on the reflectance and the photo-emissivity of the surface. DTIC
Reflectance; Solar Radiation; Spacecraft Charging; Sunlight; Surface Properties; Synchronous Satellites; Ultraviolet Radiation
20060015435 Air Force Research Lab., Hanscom AFB, MA USA
Introduction to Violent Sun-Earth Connection Events of October-November 2003
Gopalswamy, N; Barbieri, L; Cliver, E W; Lu, G; Plunkett, S P; Skoug, R M; Sep 30, 2005; 7 pp.; In English Report No.(s): AD-A443280; AFRL-VS-HA-TR-2006-1011; No Copyright; ONLINE: http://hdl.handle.net/100.2/ADA443280; Avail.: CASI: A02, Hardcopy
The violent solar eruptions of October-November 2003 are one of the best observed outbreaks of intense solar activity to date. These events, referred to as the Halloween storms, are extreme events in terms of both their source properties at the Sun and their heliospheric consequences. The plasma, particle, and electromagnetic consequences of these events were detected at several locations in the heliosphere thanks to the distributed network of spacecraft. Disturbances associated with two of the October-November 2003 eruptions arrived at Earth in less than a day. Historically, only 13 such 'fast transit' events, including the Carrington event of 1 September 1859, have been observed. Remarkably, the two fast transit events in October 2003 occurred on consecutive days, following a delay of over 30 years from the previous such event on 4 August 1972. Several aspects of the Halloween storms, including active region size and potential energy, flare occurrence rate and peak intensity, CME speed and energy, shock occurrence rate, solar energetic particle (SEP) occurrence rate and peak intensity, and the geomagnetic storm intensity, displayed extreme behavior. This outbreak of strong solar activity resulted in a broad spectrum of space weather impacts. About 59% of the reporting spacecraft and about 18% of the onboard instrument groups were affected by these storms. Major societal impacts also occurred. In this article, the authors present an overview of key findings on the size/impact of the Halloween storms of 2003 as published in American Geophysical Union journals (i.e., Journal of Geophysical Research, Geophysical Research Letters, and Space Weather). These articles are included here as references. DTIC
Charged Particles; Earth Atmosphere; Electromagnetic Interference; Measurement; Solar Terrestrial Interactions
20060015652 NASA Goddard Space Flight Center, Greenbelt, MD, USA
GRB 050717: A Long, Short-Lag Burst Observed by Swift and Konus
Krimm, H. A.; Hurkett, C.; Pal'shin, V.; Norris, J. P.; Zhang, B.; Barthelmy, S. D.; Burrows, D. N.; Gehrels, N.; Golenetskii, S.; Osborne, J. P.; Parsons, A. M.; Perri, M.; Willingale, R.; December 23, 2005; 24 pp.; In English; Original contains black and white illustrations Contract(s)/Grant(s): RFBR-03-02-1751; Copyright; Avail.: CASI: A03, Hardcopy
The long burst GRB 050717 was observed simultaneously by the Burst Alert Telescope (BAT) on Swift and the Konus instrument on Wind. Significant hard to soft spectral evolution was seen. Early gamma-ray and X-ray emission was detected by both BAT and the X-Ray Telescope (XRT) on Swift. The XRT continued to observe the burst for 7.1 days and detect it for 1.4 days. The X-ray light curve showed a classic decay pattern including evidence of the onset of the external shock emission at approx. 50 s after the trigger; the afterglow was too faint for a jet break to be detected. No optical, infrared or ultraviolet counterpart was discovered despite deep searches within 14 hours of the burst. The spectral lag for GRB 050717 was determined to be 2.5 +/- 2.6 ms, consistent, with zero and unusually short for a long burst. This lag measurement suggests that this burst has a high intrinsic luminosity and hence is at high redshift (z \g 2.7). 050717 provides a good example of classic prompt and afterglow behavior for a gamma-ray burst. Author
Gamma Ray Bursts; Afterglows; Emission; X Ray Telescopes; Luminosity; Gamma Rays; Actuators
20060015653 NASA Ames Research Center, Moffett Field, CA, USA
Laboratory Spectroscopy of Large Carbon Molecules and Ions in Support of Space Missions. A New Generation of Laboratory & Space Studies
Salama, Farid; Tan, Xiaofeng; Cami, Jan; Biennier, Ludovic; Remy, Jerome; [2006]; 1 pp.; In English; NASA Laboratory Astrophysics Workshop, 14-15 Feb. 2006, Las Vegas, NV, USA; No Copyright; Avail.: Other Sources; Abstract Only
Polycyclic Aromatic Hydrocarbons (PAHs) are an important and ubiquitous component of carbon-bearing materials in space. A long-standing and major challenge for laboratory astrophysics has been to measure the spectra of large carbon molecules in laboratory environments that mimic (in a realistic way) the physical conditions that are associated with the interstellar emission and absorption regions [1]. This objective has been identified as one of the critical Laboratory Astrophysics objectives to optimize the data return from space missions [2]. An extensive laboratory program has been developed to assess the properties of PAHs in such environments and to describe how they influence the radiation and energy balance in space. We present and discuss the gas-phase electronic absorption spectra of neutral and ionized PAHs measured in the UV-Visible-NIR range in astrophysically relevant environments and discuss the implications for astrophysics [1]. The harsh physical conditions of the interstellar medium characterized by a low temperature, an absence of collisions and strong VUV radiation fields - have been simulated in the laboratory by associating a pulsed cavity ringdown spectrometer (CRDS) with a supersonic slit jet seeded with PAHs and an ionizing, penning-type, electronic discharge.We have measured for the {\it first time} the spectra of a series of neutral [3,4] and ionized [5,6] interstellar PAHs analogs in the laboratory. An effort has also been attempted to quantify the mechanisms of ion and carbon nanoparticles production in the free jet expansion and to model our simulation of the diffuse interstellar medium in the laboratory [7]. These experiments provide {\it unique} information on the spectra of free, large carbon-containing molecules and ions in the gas phase.We are now, for the first time, in the position to directly compare laboratory spectral data on free, cold, PAH ions and carbon nano-sized carbon particles with astronomical observations in the UV-NIR range (interstellar UV extinction, DIBs in the NUV-NIR range). This new phase offers tremendous opportunities for the data analysis of current and upcoming space missions geared toward the detection of large aromatic systems Le., the 'new frontier space missions' (Spitzer, HST, COS, JWST, SOFIA,...). Author
Polycyclic Aromatic Hydrocarbons; Carbon; Laboratory Astrophysics; Absorption Spectra; Gas-Ion Interactions; Radiation Distribution; Electronic Spectra; Collisions
20060015654 NASA Ames Research Center, Moffett Field, CA, USA
Computational Spectroscopy of Polycyclic Aromatic Hydrocarbons In Support of Laboratory Astrophysics
Tan, Xiaofeng; Salama, Farid; [2006]; 1 pp.; In English; NASA Laboratory Astrophysics Workshop, 14-16 Feb. 2006, Las Vegas, NV, USA Contract(s)/Grant(s): RTOP 188-01-15; No Copyright; Avail.: Other Sources; Abstract Only
Polycyclic aromatic hydrocarbons (PAHs) are strong candidates for the molecular carriers of the unidentified infrared bands (UIR) and the diffuse interstellar bands (DIBs). In order to test the PAH hypothesis, we have systematically measured the vibronic spectra of a number of jet-cooled neutral and ionized PAHs in the near ultraviolet (UV) to visible spectral ranges using the cavity ring-down spectroscopy. To support this experimental effort, we have carried out theoretical studies of the spectra obtained in our measurements. Ab initio and (time-dependent) density.functiona1 theory calculations are performed to obtain the geometries, energetics, vibrational frequencies, transition dipole moments, and normal coordinates of these PAH molecules. Franck-Condon (FC) calculations and/or vibronic calculations are then performed using the calculated normal coordinates and vibrational frequencies to simulate the vibronic spectra. It is found that vibronic interactions in these conjugated pi electron systems are often strong enough to cause significant deviations from the Born-Oppenheimer (BO) approximation. For vibronic transitions that are well described by the BO approximation, the vibronic band profiles are simulated by calculating the rotational structure of the vibronic transitions. Vibronic oscillator strength factors are calculated in the frame of the FC approximation from the electronic transition dipole moments and the FC factors. This computational effort together with our experimental measurements provides, for the first time, powerful tools for comparison with space-based data and, hence, a powerful approach to understand the spectroscopy of interstellar PAH analogs and the nature of the UIR and DIBs. Author
Polycyclic Aromatic Hydrocarbons; Laboratory Astrophysics; Spectroscopy; Ultraviolet Spectra; Dipole Moments
20060015715 NASA Marshall Space Flight Center, Huntsville, AL, USA
2-D Drift Velocities from the IMAGE EUV Plasmaspheric Imager
Gallagher, D. L.; January 2006; 1 pp.; In English; No Copyright; Avail.: Other Sources; Abstract Only
The IMAGE Mission extreme ultraviolet imager (EW) observes He(+) plasmaspheric ions throughout the inner magnetosphere. Limited by ionizing radiation and viewing close to the Sun, images of the He(+) distribution are available every 10 minutes for many hours as the spacecraft passes through apogee in its highly elliptical orbit. As a consistent constituent at about 15%, He(+) is an excellent surrogate for monitoring all of the processes that control the dynamics of plasmaspheric plasma. In particular, the motion of He' transverse to the ambient magnetic field is a direct indication of convective electric fields. The analysis of boundary motions has already achieved new insights into the electrodynamic coupling processes taking place between energetic magnetospheric plasmas and the ionosphere. Yet to be fulfilled, however, is the original promise that global E W images of the plasmasphere might yield two-dimensional pictures of mesoscale to macro-scale electric fields in the inner magnetosphere. This work details the technique and initial application of an IMAGE EUV analysis that appears capable of following thermal plasma motion on a global basis. Author
Space Plasmas; Helium; Extreme Ultraviolet Radiation; Thermal Plasmas; Plasmasphere; Mesoscale Phenomena; Ionizing Radiation; Inner Radiation Belt; Apogees
20060015809 Air Force Research Lab., Hanscom AFB, MA USA
The Use of Geophysical Data in Studies of the Historical Solar-Terrestrial Environment
Shea, M A; Smart, D F; Sep 29, 2004; 12 pp.; In English Contract(s)/Grant(s): Proj-2311 Report No.(s): AD-A443513; AFRL-VS-HA-TR-2006-1009; No Copyright; ONLINE: http://hdl.handle.net/100.2/ADA443513; Avail.: CASI: A03, Hardcopy
Recent studies of the solar-terrestrial environment for the past 500 years have necessitated the use of a variety of historical databases: nitrates in ice cores, knowledge of large volcanic eruptions, sunspot numbers, mid-latitude aurora, and geomagnetic records. The nitrate data are being used to identify large solar proton fluence events. The volcanic records help to provide time markers for the ice core. The records of major geomagnetic storms and mid-latitude aurora have been used for additional identification. It also is known that the Earth's magnetic field is evolving with a present rapid decrease in magnitude. In addition, the wandering magnetic pole must be considered in ascertaining what was 'mid latitude' in historic times versus 'mid latitude' in 2000. The authors illustrate how these databases are being used in recent studies of historic solar proton events. Sections are as follows: solar proton events in polar ice, volcano records for ice core dating, geomagnetic and auroral data, and geomagnetic field data. DTIC
Climate; Earth Atmosphere; Geomagnetism; Geophysics; Histories; Ice Reporting; Magnetic Storms; Polar Caps; Solar Activity; Solar Protons
20060015814 Maryland Univ., College Park, MD USA
A Study of the Frequency of Occurrence of Large-Fluence Solar Proton Events and the Strength of the Interplanetary Magnetic Field
McCracken, K G; Dreschhoff, G A; Smart, D F; Shea, M A; Oct 2, 2004; 15 pp.; In English Contract(s)/Grant(s): Proj-2311 Report No.(s): AD-A443530; No Copyright; ONLINE: http://hdl.handle.net/100.2/ADA443530; Avail.: CASI: A03, Hardcopy
It has been shown previously that the number of very-large-fluence solar proton events inferred for the period since 1561 were more frequent at times of low solar activity (e.g., following the recovery from the Maunder minimum), than in the present epoch of high solar activity. An inverse dependence is demonstrated between the probability of observation of the very large-fluence solar proton events and the strength of the interplanetary magnetic field derived from empirical predictions. Using the observed dependence, it is predicted and demonstrated that large-fluence solar proton events have been observed at Earth more frequently near the recurrent minima of the solar activity cycle in the past than during the present epoch. We show that these results are explicable in terms of the linear dependence of the Alfven velocity upon the strength of the interplanetary magnetic field, leading to higher shock compression ratios in the past. These results indicate that this aspect of 'solar weather' will be significantly influenced by the prevailing strength of the interplanetary magnetic field, and that recurrence of solar conditions similar to those of the solar activity minimum of solar cycles 12-14 (1878.9-1913.6) would be accompanied by a factor of ~4 increase in the occurrence of large-fluence solar proton events. DTIC
Fluence; Frequencies; Interplanetary Magnetic Fields; Interplanetary Space; Magnetic Fields; Occurrences; Solar Activity; Solar Protons
20060015820 Air Force Research Lab., Hanscom AFB, MA USA
Coronal Shocks of November 1997 Revisited: The CME-Type II Timing Problem
Cliver, E W; Nitta, N V; Thompson, B J; Zhang, J; Aug 24, 2004; 36 pp.; In English Contract(s)/Grant(s): Proj-2311 Report No.(s): AD-A443539; AFRL-VS-HA-TR-2006-1012; No Copyright; ONLINE: http://hdl.handle.net/100.2/ADA443539; Avail.: CASI: A03, Hardcopy
We re-examine observations bearing on the origin of metric type II bursts for six impulsive solar events in November 1997. Previous analyses of these events indicated that the metric type IIs were due to flares (either blast waves or ejecta). Our point of departure was the study of Zhang et al. (2001) based on the Large Angle and Spectrometric Coronagraph's C1 instrument (occulting disk at 1.1 R(sub-O)) that identified the rapid acceleration phase of coronal mass ejections (CMEs) with the rise phase of soft X-ray light curves of associated flares. We find that the inferred onset of rapid CME acceleration in each of the six cases occurred 1-3 min before the onset of metric type II emission, in contrast to the results of previous studies for certain of these events that obtained CME launch times ~25-45 min earlier than type II onset. The removal of the CME-metric type II timing discrepancy in these events and, more generally, the identification of the onset of the rapid acceleration phase of CMEs with the flare impulsive phase undercuts a significant argument against CMEs as metric type II shock drivers. In general, the six events exhibited: (1) ample evidence of dynamic behavior [soft X-ray ejecta, extreme ultra-violet imaging telescope (EIT) dimming onsets, and wave initiation (observed variously in H-alpha, EUV, and soft X-rays)] during the inferred fast acceleration phases of the CMEs, consistent with the cataclysmic disruption of the low solar atmosphere one would expect to be associated with a CME; and (2) an organic relationship between EIT dimmings (generally taken to be source regions of CMEs) and EIT waves (which are highly associated with metric type II bursts) indicative of a CME-driver scenario. DTIC
Bursts; Coronal Mass Ejection; Coronas; Data Transmission; Shock Waves; Solar Flares
20060015822 Air Force Research Lab., Hanscom AFB, MA USA
Relation of Decline Characteristics of 2-4.6 MeV Protons in SEP Events to Solar Wind Parameters
Daibog, E I; Kahler, S; Kecskemety, K; Logachev, Y I; Jan 4, 2005; 6 pp.; In English Contract(s)/Grant(s): Proj-2311 Report No.(s): AD-A443541; AFRL-VS-HA-TR-2006-1007; No Copyright; ONLINE: http://hdl.handle.net/100.2/ADA443541; Avail.: CASI: A02, Hardcopy
The shape of the particle flux decline in solar energetic particle (SEP) events is of particular importance in understanding the propagation of energetic particles in the interplanetary medium. Power-law time profiles indicate the dominance of diffusive propagation, whereas exponential-law decline emphasizes convection transport and adiabatic deceleration. Values obtained theoretically for the decay time in the latter case are reasonably close to the fitted slopes in nearly half of all events when the solar wind speed stays nearly constant. Dependencies of characteristic decay time tau and spectral index gamma on environmental plasma parameters are considered. Parts of exponential-law declines when solar wind speed: (a) decreases with time, (b) is constant, and (c) increases with time through the interval are analyzed separately. Both average values and dispersions of size distributions of tau for these three groups markedly differ in accordance with theoretical expectations. DTIC
Charged Particles; Independent Variables; Protons; Solar Wind
20060015823 Air Force Research Lab., Hanscom AFB, MA USA
The Production of Near-Relativistic Electrons by CME-Driven Shocks
Kahler, S W; Aurass, H; Mann, G; Klassen, A; Jan 2005; 9 pp.; In English Contract(s)/Grant(s): Proj-2311 Report No.(s): AD-A443542; AFRL-VS-HA-TR-2006-1005; No Copyright; ONLINE: http://hdl.handle.net/100.2/ADA443542; Avail.: CASI: A02, Hardcopy
The solar sources of near-relativistic (E \g30 keV) electron events observed at 1 AU are poorly understood. In general, the solar injection times deduced from the observed 1 AU onset times and assumed 1.2 AU travel distances yield injection times about 10 minutes after the associated flare impulsive phases and type III radio burst times. One interpretation is that the apparent delays occur in the interplanetary medium, probably due to scattering of the electrons. If the injection times are delayed from the impulsive phases, the electron acceleration might take place in CME-driven shocks. Here a large number of electron events observed with the UC/Berkeley 3DP detector on the Wind spacecraft are compared with CMEs observed by the Lasco coronagraph on SOHO and with type II bursts observed by the 40 to 800 MHz radio receiver at the Astrophysikalisches Institut Potsdam (AIP) and by the 20 kHz to 14 MHz WAVES instrument on the Wind spacecraft. The acceleration of at least some of the electron events is not consistent with the shock hypothesis. DTIC
Coronal Mass Ejection; High Energy Electrons; Relativistic Particles
20060015824 Air Force Research Lab., Hanscom AFB, MA USA
Fast Coronal Mass Ejection Environments and the Production of Solar Energetic Particle Events
Kahler, S W; Vourlidas, A; Oct 5, 2005; 9 pp.; In English Contract(s)/Grant(s): Proj-2311 Report No.(s): AD-A443543; AFRL-VS-HA-TR-2006-1014; No Copyright; ONLINE: http://hdl.handle.net/100.2/ADA443543; Avail.: CASI: A02, Hardcopy
The search continues for coronal environmental factors that determine whether a fast coronal mass ejection (CME) results in a solar energetic particle (SEP) event at 1 AU. From a plot of peak 20 MeV SEP intensities versus associated CME speeds we select for comparison two groups of fast, wide, western hemisphere CMEs observed with the LASCO coronagraph from 1998 to 2002. The SEP-rich CME group produced the largest observed SEP events, and the SEP-poor CME group produced the smallest or no observed SEP events. The major differences are that the SEP-rich CMEs are brighter and more likely to be streamer blowouts and to follow colocated CMEs within 12 or 24 hours. The SEP-poor CMEs are fainter and less likely to interact with streamers or to follow preceding colocated CMEs. Thus we confirm the recent result that the SEP event peak intensities are higher when the associated driver CMEs are preceded within a day by wide CMEs at the same locations. However, the enhanced brightness, and therefore mass, of the SEP-rich CMEs appears to be their most dominant characteristic and suggests that either large longitudinal and latitudinal extents or high densities are needed for fast CMEs to produce SEPs. DTIC
Coronal Mass Ejection; Energetic Particles; Solar Activity; Solar Corpuscular Radiation; Solar Flares; Solar Physics; Solar Storms
20060015836 Air Force Research Lab., Hanscom AFB, MA USA
Characteristic Times of Gradual Solar Energetic Particle Events and Their Dependence on Associated Coronal Mass Ejection Properties
Kahler, S W; Aug 1, 2005; 10 pp.; In English Contract(s)/Grant(s): Proj-2311 549 Report No.(s): AD-A443560; AFRL-VS-HA-TR-2006-1013; No Copyright; ONLINE: http://hdl.handle.net/100.2/ADA443560; Avail.: CASI: A02, Hardcopy
We use 20 MeV proton intensities from the EPACT instrument on Wind and coronal mass ejections (CMEs) from the LASCO coronagraph on SOHO observed during 1998-2002 to statistically determine three characteristic times of gradual solar energetic particle (SEP) events as functions of solar source longitude: (1) T(sub-O), the time from associated CME launch to SEP onset at 1 AU; (2) T(sub-R), the rise time from SEP onset to the time when the SEP intensity is a factor of 2 below peak intensity; and (3) T(sub-D), the duration over which the SEP intensity is within a factor of 2 of the peak intensity. Those SEP event times are compared with associated CME speeds, accelerations, and widths to determine whether and how the SEP event times may depend on the formation and dynamics of coronal/interplanetary shocks driven by the CMEs. Solar source longitudinal variations are clearly present in the SEP times, but T(sub-R) and T(sub-D) are significantly correlated with CME speeds only for SEP events in the best-corrected longitude range. No significant correlations between the SEP times and CME accelerations are found except for T(sub-D) in one longitude range, but there is a weak correlation of T(sub-R) and T(sub-D) with CME widths.We also find no correlation of any SEP times with the solar wind O(+7)/O(+6) values, suggesting no dependence on solar wind stream type. The SEP times of the small subset of events occurring in interplanetary CMEs may be slightly shorter than those of all events. DTIC
Coronal Mass Ejection; Energetic Particles; Solar Activity; Solar Corpuscular Radiation; Solar Flares; Solar Physics; Solar Storms; Solar Wind
20060015837 Air Force Research Lab., Hanscom AFB, MA USA
On the Origins of Solar EIT Waves
Cliver, E W; Laurenza, M; Storini, M; Thompson, B J; Sep 20, 2005; 9 pp.; In English Contract(s)/Grant(s): Proj-2311 Report No.(s): AD-A443562; AFRL-VS-HA-TR-2006-1010; No Copyright; ONLINE: http://hdl.handle.net/100.2/ADA443562; Avail.: CASI: A02, Hardcopy
Approximately half of the large-scale coronal waves identified in images obtained by the Extreme-Ultraviolet Imaging Telescope (EIT) on the Solar and Heliospheric Observatory from 1997 March to 1998 June were associated with small solar flares with soft X-ray intensities below C class. The probability of a given flare of this intensity having an associated EIT wave is low. For example, of ~8,000 B-class flares occurring during this 15 month period, only 1% were linked to EIT waves. These results indicate the need for a special condition that distinguishes flares with EIT waves from the vast majority of flares that lack wave association. Various lines of evidence, including the fact that EIT waves have recently been shown to be highly associated with coronal mass ejections (CMEs), suggest that this special condition is a CME. A CME is not a sufficient condition for a detectable EIT wave, however, because we calculate that 5 times as many front-side CMEs as EIT waves occurred during this period, after taking the various visibility factors for both phenomena into account. In general, EIT wave association increases with CME speed and width. DTIC
Coronal Mass Ejection; Imaging Techniques; Solar Flares; Telescopes; Ultraviolet Spectrometers; Ultraviolet Telescopes
20060015838 Air Force Research Lab., Hanscom AFB, MA USA
Detection and Diagnostics of a Coronal Shock Wave Driven by a Partial-Halo Coronal Mass Ejection on 2000 June 28
Ciaravella, A; Raymond, J C; Kahler, S W; Vourlidas, A; Li, J; Mar 10, 2005; 9 pp.; In English Contract(s)/Grant(s): Proj-2311 Report No.(s): AD-A443563; AFRL-VS-HA-TR-2006-1006; No Copyright; ONLINE: http://hdl.handle.net/100.2/ADA443563; Avail.: CASI: A02, Hardcopy
A fast partial-halo coronal mass ejection (CME) was observed on 2000 June 28 by instruments on the SOHO spacecraft. The CME leading edge and filamentary cold core were detected over the northwest limb at 2.32 R(circle dot solar) by the SOHO UV Coronagraph Spectrometer (UVCS). The broad profile of the O VI lambda-1032 line gives evidence of a shock front at the leading edge, supporting the identification of white-light CME sharp leading edges as fast-mode shocks. Line-of-sight speeds are as high as 1500 km s(-1), comparable to the projected speed obtained from LASCO. Pumping of the O VI lambda-1032 by Ly-beta (upsilon=1810 km s(-1)) and of O VI lambda-1037 by O VI lambda-1032 (upsilon=1648 km s(-1)) were detected, which provide diagnostics of outflow speed and density. The angle of the ejecta with the plane of the sky is obtained, combining the projected speed from LASCO with the line-of-sight speed, and varies between 7 degrees and 46 degrees. In the latter case the projected height of 2.32 R(circle dot solar) was at an actual heliocentric distance of 3.6 R(circle dot solar). An associated solar energetic particle (SEP) event was observed at the L1 point following this CME. The abundance and charge-state data are consistent with a gradual shock-accelerated SEP event.Atype II radio burst was observed at the same time the shock front was detected by UVCS. DTIC
Coronal Mass Ejection; Coronas; Diagnosis; Halos; Shock Waves; Ultraviolet Spectrometers
20060015866 State Univ. of New York, Stony Brook, NY USA
Resolving the Effects of Rotation in Altair with Long-Baseline Interferometry
Peterson, D M; Hummel, C A; Pauls, T A; Armstrong, J T; Benson, J A; Gilbreath, G C; Hutter, D J; Johnston, K J; Mozurkewich, D; Schmitt, H; Jan 10, 2006; 12 pp.; In English Report No.(s): AD-A443600; No Copyright; ONLINE: http://hdl.handle.net/100.2/ADA443600; Avail.: CASI: A03, Hardcopy
We report the successful fitting of a Roche model, with a surface temperature gradient following the von Zeipel gravity darkening law, to observations of Altair made with the Navy Prototype Optical Interferometer.We confirm the claim by Ohishi et al. that Altair displays an asymmetric intensity distribution due to rotation, the first such detection in an isolated star. Instrumental effects due to the high visible flux of this first magnitude star appear to be the limiting factor in the accuracy of this fit, which nevertheless indicates that Altair is rotating at 0:90 +or- 0:02 of its breakup (angular) velocity. Our results are consistent with the apparent oblateness found by van Belle et al. and show that the true oblateness is significantly larger owing to an inclination of the rotational axis of ~64 degrees to the line of sight. Of particular interest, we conclude that instead of being substantially evolved as indicated by its classification, A7 IV V, Altair is only barely off the zero-age main sequence and represents a good example of the difficulties rotation can introduce in the interpretation of this part of the HR diagram. DTIC
Interferometry; Resolution; Rotation
20060016015 Ohio State Univ., Columbus, OH USA
Physics-Based Radiometric Signature Modeling and Detection Algorithms of Landmines Using Electro-Optical Sensors
Liao, Wen-Jiao; Jul 2005; 283 pp.; In English; Original contains color illustrations Report No.(s): AD-A443784; AMSRD-CER-NV-TR-C240; No Copyright; Avail.: CASI: A13, Hardcopy
This work, supported by the USA RDECOM CERDEC Night Vision and Electronic Sensors Directorate, focuses on signature modeling and detection algorithms. Signature modeling helps to provide insight for sensor deployment. The model addresses relevant issues in sources, targets, and sensors. Natural sources such as thermal emission, solar radiation, and solar scattering were considered and incorporated using empirical models. A BRDF model that defines scattering and emission from rough surfaces was developed that integrates geometric relations with intrinsic surfaces properties. Stokes' vectors are used throughout this work to describe incident and scattered radiances, which permits a polarimetric study of the signatures. The simulated signatures are compared with several measured data sets from different scenarios and exhibit strong quantitative agreement. The advancements described throughout the document will serve to improve real-time mine detection. DTIC
Algorithms; Electro-Optics; Mines (Ordnance); Radiometers; Signatures; Solar Radiation; Thermal Radiation
20060016367 NASA Ames Research Center, Moffett Field, CA, USA
Near Infrared Spectra of Mixtures Relevant to Icy Satellites
Mastrapa, Rachel M. E.; Bernstein, Max P.; Sanford, Scott A.; August 30, 2005; 1 pp.; In English; American Geophysical Union Conference, 5-9 Dec. 2005, San Francisco, CA, USA; No Copyright; Avail.: Other Sources; Abstract Only
We will present near IR spectra of ice mixtures and review the differences between spectra of mixtures and those of pure solids: the creation of new features, weakening and shifting of bands, dependence on concentration, and changes with temperature. The forbidden CO2 (2nu3) overtone at 2.134 microns (4685/cm) is absent from the spectrum of pure CO2, but present in all of the following mixtures: H2O/CO2 = 5 and = 25, H2O:CH3OH:CO2 = 100:2.5:1, and CH3OH:CO2 = 5. Also, in mixtures of H2O and any other material, we see a feature at 1.89 microns (5290/cm) that is possibly related to the dangling OH' feature at 2.73 microns (3360/cm). The features of a material in H2O are generally weaker and shifted to longer wavelength in comparison to the pure substance. For example, the largest near-IR absorption of pure solid CH4 is located at 2.324 microns (4303/cm) but is broader and at slightly longer wavelength in samples mixed with H2O. The degree of shifting and weakening depends on the ratio of the mixture. The mixture mentioned above was at a ratio of H2O/ CH4 = 3. When the ratio rises to H2O/ CH4 = 87, the CH4 feature at 2.324 microns is shifted to shorter wavelength and is much broader and weaker. In CH4/ H2O mixtures the peaks shift to higher frequency and become increasingly broad, but this trend is reversible on re-cooling, even though the phase transitions of H2O are irreversible. In short, mixtures created in the lab produce spectra that are very different from modeled combinations of end member species. Recent Cassini VIMS observations show the CO2 fundamental at 4.255 microns (2350/cm) on Iapetus [l] and at 4.26 microns (2347/cm) on Phoebe [2], while Galileo NIMS observed it at 4.25 microns (2353/cm) on Ganymede [3]. Since pure CO2 is located at 4.266 (2344/cm), the CO2 must be mixed with something else to produce the shift.Amixture of CH3OH:CO2 = 5 at 90 K shifts the fundamental to 4.262 microns (2346/cm). The shifts in the feature between satellites could indicate variations in concentration and temperature, or the introduction of a new compound, encouraging further lab investigation. Author
Near Infrared Radiation; Icy Satellites; Infrared Spectra; Carbon Dioxide; Ganymede; Galileo Spacecraft
20060016373 NASA Marshall Space Flight Center, Huntsville, AL, USA
Current Sheet Evolution In The Aftermath Of A CME Event
Bemporad, A.; Poletto, G.; Seuss, S. T.; Schwardron, N. A.; Elliott, H. A.; Raymond, J. C.; The Astrophysical Journal; January 2006; Volume 638, pp. 1110-1128; In English; Original contains color and black and white illustrations Contract(s)/Grant(s): COFIN 2003029124003; Copyright; Avail.: Other Sources
We report on SOHO UVCS observations of the coronal restructuring following a coronal mass ejection (CME) on 2002 November 26, at the time of a SOHO-Ulysses quadrature campaign. Starting about 1.5 hr after a CME in the northwest quadrant, UVCS began taking spectra at 1.7 R, covering emission from both cool and hot plasma. Observations continued, with occasional gaps, for more than 2 days. Emission in the 974.8 A line of [Fe XVIII], indicating temperatures above 6 x 10(exp 6) K, was observed throughout the campaign in a spatially limited location. Comparison with EIT images shows the [Fe XVIII] emission to overlie a growing post-flare loop system formed in the aftermath of the CME. The emission most likely originates in a current sheet overlying the arcade. Analysis of the [Fe XVIII] emission allows us to infer the evolution of physical parameters in the current sheet over the entire span of our observations: in particular, we give the temperature versus time in the current sheet and estimate its density. At the time of the quadrature, Ulysses was directly above the location of the CME and intercepted the ejecta. High ionization state Fe was detected by the Ulysses SWICS throughout the magnetic cloud associated with the CME, although its rapid temporal variation suggests bursty, rather than smooth, reconnection in the coronal current sheet. The SOHO-Ulysses data set provided us with the unique opportunity of analyzing a current sheet structure from its lowest coronal levels out to its in situ properties. Both the remote and in situ observations are compared with predictions of theoretical CME models. Author
Coronal Mass Ejection; Soho Mission; Coronas; Ejecta; High Temperature Plasmas; Ulysses Mission; Magnetic Clouds; Ionization; Current Sheets
Source: NASA
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