Simulation experiments of the effect of space environment on bacteriophage and DNA thin films.

The main goal of PUR experiment (phage and uracil response) is to examine and quantify the effect of specific space conditions on nucleic acid models. To achieve this an improved method was elaborated for the preparation of DNA and bacteriophage thin films. The homogeneity of the films was controlled by UV spectroscopy and microscopy. To provide experimental evidence for the hypothesis that interplanetary transfer of the genetic material is possible, phage T7 and isolated T7 DNA thin films have been exposed to selected space conditions: intense UVC radiation (lambda=254 nm) and high vacuum (10(-4) Pa). The effects of DNA hydration, conformation and packing on UV radiation damage were examined. Characteristic changes in the absorption spectrum, in the electrophoretic pattern of DNA and the decrease of the amount of PCR products have been detected indicating the photodamage of isolated and intraphage DNA.     

Airglow atmospheric imager on board the ‘IK-Bulgaria-1300’ satellite

This paper shows the possibilities of the optical scanning imager for investigation of the structure of the auroral, SAR and tropical arcs and in this way to study the particle precipitation, neutral winds across the magnetic equator, drifts, electric fields and the current systems in the ionosphere.     

Biological UV dosimeters in simulated space conditions.

Polycrystalline uracil thin layers participate in the phage and uracil response (PUR) experiment, assigned to the biological dosimetry of the extraterrestrial solar radiation on the International Space Station (ISS). In ground based experiments (experiment verification tests), the following space parameters were simulated and studied: temperature, vacuum and short wavelength UV (UV-C, down to 200 nm) radiation. The closed uracil samples proved to be vacuum-tight for 7 days. In the tested temperature range (from -20 to +40 degrees C) the uracil samples are stable. The kinetic of dimer formation (dimerization) and reversion (monomerization) of uracil dimers due to short wavelength UV radiation was detected, the monomerization efficiency of the polychromatic deuterium lamp is higher than that of the germicidal lamp. A mathematical model describing the kinetic of monomerization-dimerization was constructed. Under the influence of UV radiation the dimerization-monomerization reactions occur simultaneously, thus the additivity law of the effect of the various wavelengths is not applicable.     

The MELISSA pilot plant facility as as integration test-bed for advanced life support systems.

The different advances in the Micro Ecological Life Support System Alternative project (MELISSA), fostered and coordinated by the European Space Agency, as well as in other associated technologies, are integrated and demonstrated in the MELISSA Pilot Plant laboratory. During the first period of operation, the definition of the different compartments at an individual basis has been achieved, and the complete facility is being re-designed to face a new period of integration of all these compartments. The final objective is to demonstrate the potentiality of biological systems such as MELISSA as life support systems. The facility will also serve as a test bed to study the robustness and stability of the continuous operation of a complex biological system. This includes testing of the associated instrumentation and control for a safe operation, characterization of the chemical and microbial safety of the system, as well as tracking the genetic stability of the microbial strains used. The new period is envisaged as a contribution to the further development of more complete biological life support systems for long-term manned missions, that should be better defined from the knowledge to be gained from this integration phase. This contribution summarizes the current status of the Pilot Plant and the planned steps for the new period.     

Dependence of ESP intensity on collisionless shock wave characteristics

Flux variations of 1 – 5 MeV protons are studied in energetic storm particle events with respect to the preshock solar wind plasma parameters and to the thickness of the collisionless interplanetary shock wave. It is found that the peak intensity in ESP events depends on pre-shock plasma density and on the thickness of the transition region. These relations predict, in agreement with recent observations, the increase of ESP events at larger heliocentric distances.     

European present and future scientific activities in the field of low gravity research

This report deals with the present plans and philosophy of the European Space Agency as regards the interest and the justification for a European Experimental Research Program in Space. It offers recommendations to be considered by both the space investigators and the E.S.A. executive in order to achieve the most urgent needs.     

Order out of Randomness: Self-Organization Processes in Astrophysics

Self-organization is a property of dissipative nonlinear processes that are governed by a global driving force and a local positive feedback mechanism, which creates regular geometric and/or temporal patterns, and decreases the entropy locally, in contrast to random processes. Here we investigate for the first time a comprehensive number of (17) self-organization processes that operate in planetary physics, solar physics, stellar physics, galactic physics, and cosmology. Self-organizing systems create spontaneous “order out of randomness”, during the evolution from an initially disordered system to an ordered quasi-stationary system, mostly by quasi-periodic limit-cycle dynamics, but also by harmonic (mechanical or gyromagnetic) resonances. The global driving force can be due to gravity, electromagnetic forces, mechanical forces (e.g., rotation or differential rotation), thermal pressure, or acceleration of nonthermal particles, while the positive feedback mechanism is often an instability, such as the magneto-rotational (Balbus-Hawley) instability, the convective (Rayleigh-Bénard) instability, turbulence, vortex attraction, magnetic reconnection, plasma condensation, or a loss-cone instability. Physical models of astrophysical self-organization processes require hydrodynamic, magneto-hydrodynamic (MHD), plasma, or N-body simulations. Analytical formulations of self-organizing systems generally involve coupled differential equations with limit-cycle solutions of the Lotka-Volterra or Hopf-bifurcation type.