A study of positrons from Soviet nuclear powered satellites as tracers for magnetospheric research

Two Soviet satellites carrying nuclear reactors operated in circular 790 km orbits (65° inclination) in 1987 and 1988. Positrons generated in the satellites' surfaces by the intense reactor gamma radiation escaped and were trapped for periods of minutes to hours in the geomagnetic field. These positrons have been observed on many occasions by gamma ray sensors on the SMM satellite (in 500 km orbit) which identify the positrons by the 511 keV gamma rays created when they annihilate in the satellite surface. The SMM detector provides a time resolution of 64 milliseconds. It has recorded positron rise-times of less than 0.5 second (corresponding to a satellite travel distance of about 1 positron gyroradius) on many occasions as it encounters the low-L edge of positrons injected by the Soviet satellites as far as half-way around the earth. We are studying the potential of these sharply defined positron shells as magnetospheric tracers and as a means for examining particle diffusion and loss processes.     

Long period magnetospheric oscillations at discrete frequencies: The results of a multi-station analysis

A multi-station analysis of geomagnetic field measurements conducted for a remarkable case event, at a European and an American array shows that, although several aspects of the geomagnetic field observations show a clear latitudinal and local time dependence, simultaneous oscillations at discrete frequencies (f ≈ 1.0, 1.3, 2.2 and 3.2 mHz) are almost ubiquitously detected, from low to high latitudes both in the light and dark sector. They are driven by fluctuations of the solar wind density and dynamic pressure at the same frequencies, via the modulation of the magnetopause current. We also report clear evidence for the occurrence of resonant coupling (at f ≈ 2.2 and 3.2 mHz) between such modes and high latitude field lines. Due to the variable length of the field line through the day, oscillation modes at the same frequencies resonate at different latitudes in the daytime and nighttime region, respectively.     

A review of recent results on cosmic gamma-ray bursts

The results obtained on cosmic gamma-ray bursts over the last several years are reviewed and compared with the older “historical” results. Fine time resolution measurements of burster light curves continue to reveal structure at the millisecond and sub-millisecond level, suggesting a compact object origin. Similarly, the evolution of the low energy X-ray spectra of bursts towards shapes consistent with 1–2 keV blackbodies may be interpreted in terms of a neutron star origin, as can the continuing detection of absorption and emission features. The statistical evidence, however, argues strongly for an isotropic distribution which has been completely sampled. To reconcile this with galactic neutron stars requires the assumption that they are Population II objects. Counterpart searches have evolved to the point where they may be carried out within days of an event, and a soft X-ray source has now been detected in the error box of one recent burst.     

A review on recent development of space solar power

Space solar power(SSP) system, a major type of space-based power-generating equipment, is an important infrastructure providing massive, continuous, and stable green electricity by utilizing solar energy in space. Many countries and organizations consider SSP to be one of the most promising clean energy sources. The historical activities of SSP in the world are summarized. This review focuses on the significant development of SSP during the last 10 years, which is the most important period for SSP. The latest international SSP development programmes in the United States, ESA, Japan, China, UK and Korea are presented. Some significant solar power satellite(SPS) concepts proposed in the decade, including typical SPS-ALPHA, MR-SPS, CASSIOPeiA SPS, et al., are introduced. The technical and non-technical challenges are also listed and several important in-space demonstration missions in recent years and in the near future are introduced. The conclusion is that the next 5 to 10 years will be an important period for rapidly developing the key technologies and conducting on-orbit demonstration and application. Controlling the mutual position relationship between the solar array and the transmitting antenna becomes a core issue to be considered in the innovative design of the SPS. Wireless power transmission technologies would be the demonstration focus for the first step. It is expected that the first commercial SPS would be constructed as early as 2040.     

A review on the upper atmospheric sodium observations from India: Insights

This review article briefly brings out the historical development of atmospheric sodium (Na) measurements over India and the importance of coordinated measurements with multiple techniques to address physical processes in the Earth's upper atmosphere. These measurements were initiated in the early 1970s by observing Na airglow emission intensities with broad band airglow photometer from Mt. Abu, a low-latitude hill station in India. Considerable amount of night-to-night variations in nocturnal emission intensities of the Na airglow were observed. Later, investigations regarding the dependence with the magnetic activities from the equatorial and low latitudes were carried out and double-humped structures in the nocturnal variation of intensities were reported. With the advent of Na lidar at Gadanki around 2005, the measurements of atmospheric neutral Na atom concentration became possible and more frequent occurrences of sporadic Na layers over the magnetic low latitude station compared to other latitudes were detected indicating the role played by electrodynamics. Later, a possible relationship between E-region field aligned plasma irregularities and the concentration of neutral Na atoms was investigated using coordinated measurements of VHF radar and Na lidar. Further, simultaneous measurements with Na lidar and a narrow band airglow photometer with narrow field of view brought out the importance of coordinated observation wherein the characterization of gravity waves could be carried out and also revealed the importance of collisional quenching due to ambient molecules in the Na airglow emission processes. In addition, combining the ground based measurements of Na lidar and meteor wind radar along with satellite measurements made possible to hypothesize the over-turning Kelvin–Helmholtz billow in the Na layer manifests “C-type” or inverted lambda shape structures in the height-time-concentration map of neutral Na atoms. This review paper presents a synoptic view mostly based on the previously reported observations of Na airglow emission, Na lidar and coordinated Na airglow and Na lidar observations from the Indian sector and highlights the importance of simultaneous measurements of mesospheric Na and its emissions along with satellite-borne measurements to address interesting geophysical processes in the Earth's upper atmosphere.     

Neuroplastic reactivity of fish induced by altered gravity conditions: a review of recent results.

A review is being presented concerning behavioural, biochemical, histochemical and electronmicroscopical data on the influence of altered gravitational forces on the swimming performance and on the neuronal differentiation of the brain of cichlid fish larvae and adult swordtail fish that had been exposed to hyper-gravity (3g in laboratory centrifuges), hypo-gravity (>10(-2) g in a fast-rotating clinostat) and to near weightlessness (10(-4) g aboard the Spacelab D-2 mission). After long-term alterations of gravity (and parallel light deprivation), initial disturbances in the swimming behaviour followed by a stepwise regain of normal swimming modes are induced. Parallel, neuroplastic reactivities on different levels of investigation were found, such as adaptive alterations of activities of various enzymes in whole brain as well as in specific neuronal integration centers and an intraneuronal reactivity on ultrastructural level in individual brain parts and in the sensory epithelia of the inner ear. Taken together, these data reveal distinct adaptive neuroplastic reactions of fish to altered gravity conditions.     

A review of long drop tubes as a supplement/alternative to space experiments

The 100 meter high drop tube at the Marshall Space Flight Center has proven to be a viable facility for studies of containerless solidification. Advantages are that experiments are inexpensive and large numbers of specimens can be processed rapidly. It would not be unusual to run ten specimens in a day. Another significant advantage is that the undercooling behavior can be followed with sufficient sensitivity to easily detect the onset of recalescence and subsequent events.Disadvantages are the restrictions on specimen sizes and types of alloys that can be run in a microgravity environment. Practical specimen sizes range between 50 mg and 500 mg depending on the type of furnace being used. Refractory alloys can be processed in a vacuum (about 10^?5 torr) and therefore at microgravity. Non-refractory alloys demand an atmosphere (about 200 torr) to obtain appreciable undercooling before impact at the bottom of the tube. Under these conditions significant g forces result.Because of the present limitations of the 100 meter drop tube, the most definitive work has been done on niobium based alloys. Large amounts of undercooling have been observed routinely and the effects of undercooling on microstructure have been characterized in detail. X-ray diffraction, scanning electron microscopy, and transmission electron microscopy have been used to determine types of phases, amounts of phases, and compositions of phases. It is clear, as would be expected, that the results bear some resemblance to rapid solidification processing by quenching. However, there are dissimilarities due to the uniqueness of solidification by deep undercooling without quenching in long drop tubes and accompanying recalescence effects.     

The CEEF, closed ecosystem as a laboratory for determining the dynamics of radioactive isotopes.

Nuclear power generation is now confronted with a very difficult situation all over the world because of the problems of radioactive waste disposal and of the accidents, which have occurred. Nuclear power generation now supplies nearly 30% of total electric power demand in Japan. Therefore it is very difficult to change quickly the construction plans of nuclear facilities already designed. A nuclear fuel reprocessing center is now under construction in Rokkasho-Mura in Aomori Prefecture. If this center starts its operation, small amounts of 14CO2 are expected to be released into the atmosphere and will enter the global cycle. The simulation experiment of 14C trace amounts which enter into ecosystems is now being planned using stable isotope 13C within CEEF (Closed Ecology Experiment Facilities).     

The dynamics and control of the CubeSail mission: A solar sailing demonstration

The CubeSail mission is a low-cost demonstration of the UltraSail solar sailing concept (, ,  and ), using two near-identical CubeSat satellites to deploy a 260 m-long, 20 m² reflecting film. The two satellites are launched as a unit, detumbled, and separated, with the film unwinding symmetrically from motorized reels. The conformity to the CubeSat specification allows for reduction in launch costs as a secondary payload and utilization of the University of Illinois-developed spacecraft bus. The CubeSail demonstration is the first in a series of increasingly-complex missions aimed at validating several spacecraft subsystems, including attitude determination and control, the separation release unit, reel-based film deployment, as well as the dynamical behavior of the sail and on-orbit solar propulsion. The presented work describes dynamical behavior and control methods used during three main phases of the mission. The three phases include initial detumbling and stabilization using magnetic torque actuators, gravity-gradient-based deployment of the film, and steady-state film deformations in low Earth orbit in the presence of external forces of solar radiation pressure, aerodynamic drag, and gravity-gradient.     

Russian ground-level detectors of cosmic ray observations as a part of the world wide network: History and development

The history of creation and development of the network of cosmic ray stations in USSR-Russia goes back to the difficult years of the Second War (1944–1945). The Russian neutron monitor network continuously operates at the present time, having developed from a mechanical means of registration into a modern electronic system for the collection and processing of data with the results presented in the Internet in real time. Along with the improvement of the equipment and different methods of data processing, strong scientific groups, and even Institutes have grown up at a number of stations. They carry out scientific investigations on the basis of neutron monitor network data and provide the conditions for operative and real time exchange of data.     

The observations of AGNs in the 40–1300 keV energy range by the SIGMA telescope

The SIGMA telescope realizes images of the sky in the hard X-ray domain (40 keV–1.3 MeV) through a coded mask system. The extragalactic study was one of the main objectives and has brought new results in our knowledge of the Active Galactic Nuclei behavior at high energy.

In fact, the variability is the most important factor as all these objects have been showed to display strong evolution in intensity or/and spectral shape. Moreover, the discovery of a new hard X-ray source close to 3C273 and probably strongly absorbed below 40–50 keV could have many consequences in the extragalactic field.     

Survival of microorganisms in space: A review

Spores of $\text{Bacillus subtilis}$ were exposed to selected factors of space (vacuum, solar UV radiation, heavy ions of cosmic radiation), and their response was studied after recovery. These investigations were supplemented by ground-based studies under simulated space conditions. The vacuum of space did not inactivate the spores. However, vacuum-induced structural changes in the DNA, and probably in the proteins, caused a supersensitivity to solar UV radiation. This phenomenon is caused by the production of specific photoproducts in DNA and protein, which cannot be removed by normal cellular repair processes. In vegetative bacterial cells, exposed to vacuum, cell dehydration led to damage of the cell membrane, which could be partly repaired during subsequent incubation. The high local effectiveness of the cosmic heavy ions further decreases the chance that spores can survive for any length of time in space. Nonetheless, a spore travelling through space and protected from ultraviolet radiation could possibly survive an interplanetary journey. Such a situation favors panspermia as a possible explanation for the origin of life.     

The crustal dynamics data information system: A resource to support scientific analysis using space geodesy

Since 1982, the Crustal Dynamics Data Information System (CDDIS) has supported the archive and distribution of geodetic data products acquired by the National Aeronautics and Space Administration (NASA) as well as national and international programs. The CDDIS provides easy, timely, and reliable access to a variety of data sets, products, and information about these data. These measurements, obtained from a global network of nearly 650 instruments at more than 400 distinct sites, include DORIS (Doppler Orbitography and Radiopositioning Integrated by Satellite), GNSS (Global Navigation Satellite System), SLR and LLR (Satellite and Lunar Laser Ranging), and VLBI (Very Long Baseline Interferometry). The CDDIS data system and its archive have become increasingly important to many national and international science communities, particularly several of the operational services within the International Association of Geodesy (IAG) and its observing system the Global Geodetic Observing System (GGOS), including the International DORIS Service (IDS), the International GNSS Service (IGS), the International Laser Ranging Service (ILRS), the International VLBI Service for Geodesy and Astrometry (IVS), and the International Earth rotation and Reference frame Service (IERS). Investigations resulting from the data and products available through the CDDIS support research in many aspects of Earth system science and global change. Each month, the CDDIS archives more than one million data and derived product files totaling over 90 Gbytes in volume. In turn, the global user community downloads nearly 1.2 Tbytes (over 10.5 million files) of data and products from the CDDIS each month. The requirements of analysts have evolved since the start of the CDDIS; the specialized nature of the system accommodates the enhancements required to support diverse data sets and user needs. This paper discusses the CDDIS, including background information about the system and its user communities, archive contents, available metadata, and future plans.     

Mean winds of the mesosphere and lower thermosphere (60–110 km): A global distribution from radar systems (MF,Meteor, VHF)

During the last decade a large number of radars (～12) have been developed, which have produced substantial quantities of tidally-corrected mean winds data. The distribution of the radars is not global, but many areas are well covered: the Americas with Poker Flat (65°N), Saskatoon (52°N), Durham (43°N), Atlanta (34°N), Puerto Rico (18°N); Europe with Kiruna (68°), Garchy (47°N) and Monpazier (44°N); and Oceania with Christchurch (44°S), Adelaide (35°S), Townsville (20°S), and Kyoto (35°N). Zonal and meridional wind height-time cross-sections from $\text{60}\text{80}$ km (MF/Meteor Radar) to ～110 km have been prepared for the last 5–6 years. They are compared with cross-sections from CIRA-72 for zonal winds, and Groves (1969) for meridional winds.It is shown that while CIRA-72 is still a useful model for many purposes, significant differences exist between it and the new radar data. The latter demonstrate important seasonal, latitudinal, longitudinal and hemispheric variations. The new meridional cross-sections are of great value. The common features with Groves (1969) are the equatorward cells in summer near 85 km; however their strength (～10 ms^?1) and size are less. Systematic and somewhat different variations emerge at higher (?52°N) and middle (35–44°) latitudes.     

Synthesis of geophysical data with space-acquired imagery: A review

Geophysical data obtained from ground and airborne platforms have been used in the development of regional geologic models for many years. Space-acquired data and imagery have a shorter but similar history of applications. All these data may be synthesized either manually or digitally. Manual synthesis methods consist of overlaying and comparing maps, whereas digital synthesis methods consist of computer storage and analysis of registered digital data sets.A data base may include topographic, geologic, soils, aeromagnetic, gravity, radiometric, electromagnetic and geochemical data, and Landsat, Seasat, and Heat Capacity Mapping Mission (HCMM) images, all of which can be evaluated individually or compared in multiple layers (overlays).Stereographic models, useful in the correlation and interpretation of geophysical data, have been created from Landsat images by using aeromagnetic, gravity, geochemical, or topographic values to offset Landsat pixels, thus introducing parallax and permitting stereoscopic viewing.Statistical correlation has been used to determine the applicability of specific data sets to the development of geologic or exploration models. Various arithmetic functions have proven useful in developing models from such data sets.     

Space observations of comets during solar flares: A possible explanation for comet brightness outbursts

Problems connected with mechanisms for comet brightness outbursts as well as for gamma-ray bursts remain open. Meantime, calculations show that irradiation of a certain class of comet nuclei, having high specific electric resistance, by intense fluxes of energetic protons and positively charged ions with kinetic energies more than 1 MeV/nucleon, ejected from the Sun during strong solar flares, can produce a macroscopic high-voltage electric double layer with positive charge in the subsurface zone of the nucleus, during irradiation times of the order of 10–100 h at heliocentric distances around 1–10 AU. The maximum electric energy accumulated in such layer will be restricted by the electric discharge potential of the layer material. For comet nuclei with typical radii of the order of 1–10 km the accumulated energy of such natural electric capacitor is comparable to the energy of large comet outbursts that are estimated on the basis of ground based optical observations. The impulse gamma and X-ray radiation together with optical burst from the comet nucleus during solar flares, anticipated due to high-voltage electric discharge, may serve as an indicator of realization of the processes above considered. Multi-wavelength observations of comets and pseudo-asteroids of cometary origin, having brightness correlation with solar activity, using ground based optical telescopes as well as space gamma and X-ray observatories, during strong solar flares, are very interesting for the physics of comets as well as for high energy astrophysics.     

Geoeffectiveness of interplanetary shocks controlled by impact angles: A review

The high variability of the Sun’s magnetic field is responsible for the generation of perturbations that propagate throughout the heliosphere. Such disturbances often drive interplanetary shocks in front of their leading regions. Strong shocks transfer momentum and energy into the solar wind ahead of them which in turn enhance the solar wind interaction with magnetic fields in its way. Shocks then eventually strike the Earth’s magnetosphere and trigger a myriad of geomagnetic effects observed not only by spacecraft in space, but also by magnetometers on the ground. Recently, it has been revealed that shocks can show different geoeffectiveness depending closely on the angle of impact. Generally, frontal shocks are more geoeffective than inclined shocks, even if the former are comparatively weaker than the latter. This review is focused on results obtained from modeling and experimental efforts in the last 15?years. Some theoretical and observational background are also provided.     

Remote infrared observations of parent volatiles in comets: A window on the early solar system

Organic volatiles and water in Oort Cloud comets were investigated at infrared wavelengths. The detected species include H₂O, CO, CH₃OH, CH₄, C₂H₂, C₂H₆, OCS, HCN, NH₃, and H₂CO. Several daughter fragments (CN, OH, NH₂, etc.) are also measured, and OH prompt emission provides a proxy for water. Long-slit spectra are taken at high spectral dispersion and high spatial resolution, eliminating several sources of systematic error. The resulting parent volatile production rates are highly robust, permitting a sensitive search for compositional diversity among comets. Here, seven OC comets are compared. Six (including Halley) exhibit similar compositions (excepting CO and CH₄). Their low formation temperatures (30 K) suggest this group probably formed beyond 30 AU from the young sun. However, C/1999 S4 is severely depleted in hypervolatiles and also in methanol, and it likely formed near 5–10 AU. C/2001 A2 is discussed briefly to illustrate future prospects.     

An identification for GEMINGA: A review of all the available data

Dedicated X-ray, optical and radio observations aimed at the identification of the bright γ-ray source 2CG195+04 (GEMINGA) are presented. A very promising candidate is found and its properties are discussed in the context of possible astrophysical scenarios.     

Theoretical aspects of heavy ion injections in the magnetosphere: A review

The theoretically expected effects of active heavy ion injections in the magnetosphere are reviewed according to their chemical state (plasma or neutral) and their kinetic state (explosion or beam injection) of release. The early-phase effects of such injections (such as ionospheric heating, wave-particle interactions, radiation belt and ring current modifications and anomalous ionization) are briefly discussed. The need for understanding the magnetospheric modification aspects of heavy ion injections becomes more acute in the next decades when the transportation and construction of large-scale space structures would inject increasing volumes of heavy ions in the magnetosphere by both chemical and ion engines. Ion engine exhaust, in the form of a dense relatively cool plasma beam of high drift speed, represents a new regime of heavy ion magnetospheric modification, the effects of which have not been thoroughly investigated either theoretically or observationally. We envisage that the ion engine can be modified into a useful tool for scientific studies of magnetospheric dynamics since it is a source of a variety of ionic species independent of the need for photoionization.