Mutation induction in mammalian cells by very heavy ions.

V79 Chinese hamster cells were exposed to heavy ions (O to U) and assayed for mutants at the HGPRT-locus by incubation in selective medium containing 6-thioguanine. The LET ranged from 300 to 18000 keV/micrometer. Mutants could be recovered from all particle radiation but the effectivity per deposited energy decreased with atomic numbers greater than 8. The results are discussed with regard to fundamental processes of cell reactions to very heavy ions and with respect to possible implications for hazard estimations.     

New microgravity fundamental physics research areas in the ISS era

NASA's microgravity fundamental physics program has used the Space Shuttle to perform high resolutions experiments in space. As we come to the end of the Shuttle era, we will begin to perform research aboard the ISS. A large stable of ground based experiments have been selected from NASA Research Announcements in a variety of disciplines. These investigations will form the backbone from which to select future flight candidates. Research in Laser Cooling and Atomic Physics will enable us to operate highly precise clocks in space. Low temperature physics experiments will use a liquid helium facility with a six-month lifetime. This facility can also support experiments in gravitational physics. Researchers in biological physics will be offered an opportunity to develop future experiments that can benefit from space experimentation. An overview of the future research directions and the benefits to the community of performing research aboard the ISS will be presented.     

The IRS-P3 remote sensing mission

ISRO has developed the PSLV rocket (Polar Spacecraft Launch Vehicle) for polar orbiting satellites up to 1000 kg and is conducting a series of test missions. One of this is the IRS-P3, an remote sensing satellite with German participation. The payload consists of 3 scientific instruments: The wide field sensor WiFS for vegetation monitoring (ISRO), the imaging spectrometer MOS (DLR/Germany) for coastal zone and ocean studies an the X-ray astronomy payload (ISRO). The paper gives technical details and parameters on the launch vehicle, the satellite, the instruments and scientific goals and data utilization.     

Decorrelation of broadband signals by Toeplitz-Block-Toeplitzstructuring

We propose F-norm of the cross-correlation part of the array covariance matrix as a measure of correlation between the impinging signals and study the performance of different decorrelation methods in the broadband case using this measure. We first show that dimensionality of the composite signal subspace, defined as the number of significant eigenvectors of the source sample covariance matrix, collapses in the presence of multipath and the spatial smoothing recovers this dimensionality. Using an upper bound on the proposed measure, we then study the decorrelation of the broadband signals with spatial smoothing and the effect of spacing and directions of the sources on the rate of decorrelation with progressive smoothing. Next, we introduce a weighted smoothing method based on Toeplitz-block-Toeplitz (TBT) structuring of the data covariance matrix which decorrelates the signals much faster than the spatial smoothing. Computer simulations are included to demonstrate the performance of the two methods     

Hybrid life support systems with integrated fuel cells and photobioreactors for a lunar base

The development of regenerative and sustainable life support systems (LSS) is a basic prerequisite to realize human long-term habitation in space. An efficient and reliable LSS is of high importance for assembling a future research base on the Moon and for further human space exploration missions beyond Low Earth Orbit. Because of longer distance to Earth and longer transfer times new requirements appear for LSS operation and functionality in comparison to the International Space Station. The minimization of resupply mass is a crucial factor to cope with this challenge. Regenerating the main media oxygen, water, and carbon as well as demonstrating a closed loop are essential milestones for an efficient and sustainable LSS. The logical step between partly regenerative physico-chemical and bioregenerative LSS is a so-called hybrid LSS characterized by the crosslinked integration of physico-chemical and simple biological system components.The Institute of Space Systems of the University of Stuttgart (IRS), the Institute of Technical Thermodynamics (ITT) of the German Aerospace Centre (DLR) and the Fraunhofer-Institute for Interfacial Engineering and Biotechnology (IGB) work together in a project on advanced LSS research and development. The IRS will investigate the integration of a photobioreactor (PBR) for algae cultivation as biological component and a reversible proton exchange membrane fuel cell (PEFC) as physico-chemical component into an LSS. Algae in the PBR absorb the carbon dioxide exhaled by the crew and produce biomass (food) and oxygen under light influence. The oxygen can be directed either into the crew cabin or into the fuel cell for generating electricity. Vice versa the electrolysis process splits water (from the PBR or the fuel cell process) into oxygen and hydrogen used as energy storage or propellant. Main task at IRS is a feasibility study on the mentioned technologies, considering the capability of media and product regeneration as well as the ability of integration of the components into a system. Synergies, mass reduction, dissimilar redundancy, and safety enhancement must be taken into account in order to specify integration problems and filtration costs. The IGB supports this study by its expertise in PBR operation, algae cultivation, and algae species selection. The ITT investigates the coupling of the PBR with three different fuel cell types: namely PEFC, SOFC (Solid Oxide Fuel Cell), and AFC (Alkaline Fuel Cell) under electrochemical performance aspects. The influence of PBR products on performance and lifetime of the different fuel cells is of high interest. The potential of potable water and electrical power supply is considered.     

Classification and quantification of solar wind driver gases leading to intense geomagnetic storms

Classification and quantification of the interplanetary structures causing intense geomagnetic storms (Dst?≤??100?nT) that occurred during 1997–2016 are studied. The subject of this consists of solar wind parameters of seventy-three intense storms that are associated with the southward interplanetary magnetic field. About 30.14% of the storms were driven by a combination of the sheath and ejecta (S?+?E), magnetic clouds (MC) and sheath field (S) are 26% each, 10.96% by combined sheath and MCs (S?+?C), while 5.48% of the storms were driven by ejecta (E) alone. Therefore, we want to aver that for storms driven by: (1) S?+?E. The Bz is high (≥10?nT), high density (ρ) (>10?N/cm³), high plasma beta (β) (>0.8), and unspecified (i.e. high or low) structure of the plasma temperature (T) and the flow speed (V); (2) MC. The Bz is ≥10?nT, low temperature (T?≤?400,000?K), low ρ (≤10?N/cm³), high V (≥450?km), and low β (≤0.8); (3) The structures of S?+?C are similar to that of MC except that the V is low (V?≤?450?km); (4) S. The Bz is high, low T, high ρ, unspecified V, and low β; and (5) E. Is when the structures are directly opposite of the one driven by MCs except for high V. Although, westward ring current indicates intense storms, but the large intensity of geomagnetic storms is determined by the intense nature of the electric field strength and the Bz. Therefore, great storms (i.e. Dst?≤??200?nT) are manifestation of high electric field strength (≥13?mV/m).     

Adjustable box-wing model for solar radiation pressure impacting GPS satellites

One of the major uncertainty sources affecting Global Positioning System (GPS) satellite orbits is the direct solar radiation pressure. In this paper a new model for the solar radiation pressure on GPS satellites is presented that is based on a box-wing satellite model, and assumes nominal attitude. The box-wing model is based on the physical interaction between solar radiation and satellite surfaces, and can be adjusted to fit the GPS tracking data.     

Interchange Reconnection: Remote Sensing of Solar Signature and Role in Heliospheric Magnetic Flux Budget

Interchange reconnection at the Sun, that is, reconnection between a doubly-connected field loop and singly-connected or open field line that extends to infinity, has important implications for the heliospheric magnetic flux budget. Recent work on the topic is reviewed, with emphasis on two aspects. The first is a possible heliospheric signature of interchange reconnection at the coronal hole boundary, where open fields meet closed loops. The second aspect concerns the means by which the heliospheric magnetic field strength reached record-lows during the recent solar minimum period. A?new implication of this work is that interchange reconnection may be responsible for the puzzling, occasional coincidence of the heliospheric current sheet and the interface between fast and slow flow in the solar wind.     

Dynamo Scaling Laws and Applications to the Planets

Scaling laws for planetary dynamos relate the characteristic magnetic field strength, characteristic flow velocity and other properties to primary quantities such as core size, rotation rate, electrical conductivity and heat flux. Many different scaling laws have been proposed, often relying on the assumption of a balance of Coriolis force and Lorentz force in the dynamo. Their theoretical foundation is reviewed. The advent of direct numerical simulations of planetary dynamos and the ability to perform them for a sufficiently wide range of control parameters allows to test the scaling laws. The results support a magnetic field scaling that is not based on a force balance, but on the energy flux available to balance ohmic dissipation. In its simplest form, it predicts a field strength that is independent of rotation rate and electrical conductivity and proportional to the cubic root of the available energy flux. However, rotation rate controls whether the magnetic field is dipolar or multipolar. Scaling laws for velocity, heat transfer and ohmic dissipation are also discussed. The predictions of the energy-based scaling law agree well with the observed field strength of Earth and Jupiter, but for other planets they are more difficult to test or special pleading is required to explain their field strength. The scaling law also explains the very high field strength of rapidly rotating low-mass stars, which supports its rather general validity.     

Ionospheric anomalies observed over South Korea preceding the Great Tohoku earthquake of 2011

We investigated the ionospheric anomalies observed before the Tohoku earthquake, which occurred near the northeast coast of Honshu, Japan on 11 March, 2011. Based on data from a ground-based Global Positioning System (GPS) network on the Korean Peninsula, ionospheric anomalies were detected in the total electron content (TEC) during the daytime a few days before earthquake. Ionospheric TEC anomalies appeared on 5, 8 and 11 March. In particular, the ionospheric disturbances on 8 March evidenced a remarkable increase in TEC. The GPS TEC variation associated with the Tohoku earthquake was an increase of approximately 20 total electron content units (TECU), observed simultaneously in local and global TEC measurements. To investigate these pre-earthquake ionospheric anomalies, space weather conditions such as the solar activity index (F10.7) and geomagnetic activity indices (the Kp and Dst indices) were examined. We also created two-dimensional TEC maps to visual the spatial variations in the ionospheric anomalies preceding the earthquake.