Early development in the mouse: would it be affected by microgravity?

Gravity has been identified as a morphogenetic signal in Amphibian and bird embryonic development so it is plausible that it might be such in mammals as well. Since early mammalian development shows some apparently significant differences to these other groups, a brief summary of mouse embryogenesis will be given identifying events in which polarity is an important feature and consequently, in which gravity may be a causative factor. These include compaction and polarization during cleavage, establishment of the radial axis, the embryonic-abembryonic axis, the dorso-ventral axis, and the anterior-posterior axis, implantation, and the later rotation of the embryo. The experimental data on these morphogenetic steps will be discussed and an assessment of the possible involvement of gravity will be made.     

CELSS transportation analysis

Regenerative life support systems based on the use of biological material have been considered for inclusion in manned spacecraft since the early days of the United States space program. These biological life support systems are currently being developed by NASA in the Controlled Ecological Life Support System (CELSS) program. Because of the progress being achieved in the CELSS program, it is time to determine which space missions may profit from use of the developing technology. This paper presents the results of a study that was conducted to estimate where potential transportation cost savings could be anticipated by using CELSS technology for selected future manned space missions.

Six representative missions were selected for study from those included in NASA planning studies. The selected missions ranged from a low Earth orbit mission to those associated with asteroids and a Mars sortie. The crew sizes considered varied from four persons to five thousand. Other study parameters included mission duration and life support closure percentages, with the latter ranging from complete resupply of consumable life support materials to 97% closure of the life support system. The paper presents the analytical study approach and describes the missions and systems considered, together with the benefits derived from CELSS when applicable.     

Polarization imaging of dust cloud particles: Improvements and applications of the PROGRA2 instrument

The imaging system of the -PROGRA2 instrument allows to obtain maps of polarization and brightness of levitating dust clouds with a theoretical resolution of 10 μm per pixel. The measurements are conducted in microgravity during parabolic flights and on the ground by air-draught. It is then possible to measure the contribution of individual particles (grains, aggregates and agglomerates.) The size distribution can be retrieved, as well as the variation of polarization for a given phase angle with size for particles larger than 10 microns. Two different kinds of particles are considered: compact grains and (aggregates and agglomerates of) fluffy particles. Opposite results are obtained for these two kinds of particles, concerning the dependence of polarization with size and color in the visible domain for gray materials. These results, coupled with such remote sensing observations in the solar system, can then help to better understand the physical properties of solid particles and their variation in cometary comae, as well as in the Earth's atmosphere.     

Phase resolved study of the CRSF in MX 0656-072

MXB 0656-072 is an accreting X-ray pulsar with a Be star companion, showing notable emission in H. In October 2003 this system exhibited a large and extended X-ray outburst. RXTE observations during this outburst indicated a pulse period of 160.4 s and a cyclotron resonance scattering feature in the spectrum at 32 keV. This paper presents pulse profile analysis and phase-resolved X-ray spectroscopy of RXTE observations during this outburst.     

Advances in space research nonlinear dependence of Dst and AE indices on the electric field of magnetic clouds

Using the Dst and AE geomagnetic index values and parameters of interplanetary magnetic field and solar wind we have examined the geoeffectiveness of transient ejections in the solar wind, namely, magnetic clouds and high-speed streams. It is found that for magnetic clouds the dependences of indices on the solar wind electric field are nonlinear of different kind. In contrast to magnetic clouds, the dependence of Dst and AE geomagnetic index values on the solar wind electric field agrees closely with the linear one for high-speed streams. We suggest approximating formulas to describe dependences obtained taking into account the relation of the electric field transpolar potential to the electric field and dynamic pressure of the solar wind. We suppose that the interplanetary magnetic field fluctuations also contribute to these dependences.     

The SOHO concept and its realisation

The Solar and Heliospheric Observatory (SOHO) — a space observatory to be placed, in 1995, 1.5 Gm sunward from the Earth in a halo orbit around the L1 Lagrange point — will investigate:

the solar corona, its heating and expansion into the solar wind, by both studying the radiation emerging from the outer solar atmosphere and in-situ solar wind measurements near 1 AU, and

the structure and dynamics of the solar interior by the method of helioseismology.

The science policy evolution leading to this comprehensive observatory concept is described. SOHO's link to the space-plasma-physics mission CLUSTER — devoted to the three-dimensional study of small structures in the magnetosphere — within the Solar Terrestrial Science Programme (STSP) and the embedding of STSP in the much larger International Solar Terrestrial Physics (ISTP) Programme are cited as well. The scientific subjects to be addressed by SOHO are introduced, and their current status assessed. Subsequently, the measurements required to advance these subjects are stated quantitatively and the payload, which will actually perform these measurements, is presented. The mission design, comprising spacecraft, orbit, operations and the data and ground systems are described. The special efforts made to obtain a reliable radiometric calibration of the instruments observing the Sun in the extreme-ultraviolet and to achieve a stable sensitivity through extreme cleanliness of spacecraft and instruments are emphasized and substantiated.     

Experiment "Seeds" on Biokosmos 9. Dosimetric part.

The aim of the experiment "Seeds" on the Sowjetic satellite Biokosmos 9 was the observation of mutagenic effects caused at special loci of seeds of Arabidopsis thaliana and assigned to particles of the Cosmic radiation. Two types of exposure units were flown: A low-shielding unit Type I, mounted at the surface of the satellite (1.4 g/cm2 shielding) and, for comparison, an identical item inside (16 g/cm2 shielding), using nuclear emulsion as track detectors. A Type II unit, flown inside (18g/cm2 shielding) was mounted with AgCl track detectors. The layout will be briefly described. A first set of dosimetric data from the physical evaluation of the experiment will be presented. The subdivision into charge- and LET-groups shows a rather high contribution of the intermediate LET-group (350-1000 MeV/cm) due to medium heavy particles (Z = 6-10) and to enders of light (p, alpha) particles.     

Mutagenic effects of heavy ions in bacteria.

The peculiarities and mechanisms of the mutagenic action of gamma-rays and heavy ions on bacterial cells have been investigated. Direct mutations in the lac-operon of E. coli in wild type cells and repair deficient strains have been detected. Furthermore, the induction of revertants in Salmonella tester strains was measured. It was found that the mutation rate was a linear-quadratic function of dose in the case of both gamma-rays and heavy ions with LET up to 200 keV/micrometer. The relative biological effectiveness (RBE) increased with LET up to 20 keV/micrometer. Low mutation rates were observed in repair deficient mutants with a block of SOS-induction. The induction of SOS-repair by ionizing radiation has been investigated by means of the "SOS-chromotest" and lambda-prophage induction. It was shown that the intensity of the SOS-induction in E. coli increased with increasing LET up to 40-60 keV/micrometer.     

Polarization Studies of Contribution of Aerosol Scattering to the Glow of Twilight Sky

The paper is devoted to studies and a quantitative estimation of the influence of scattering of direct solar radiation by particles of tropospheric aerosols in the period of light twilight, close to sunrise and sunset. Polarization measurements of the twilight sky in two broad spectral bands lying near the standard bands V and R form the basis of these studies. The measurements were carried out in 2002 and 2003 at the Southern Laboratory (Crimea) of the Sternberg Astronomical Institute. The twilight period during which the single aerosol scattering becomes significant is isolated. The character of its influence on the intensity and polarization of the twilight sky is demonstrated. A method is suggested to evaluate polarization of the single aerosol scattering and its contribution to the general brightness of the twilight sky background. The method is based on differential characteristics of the background near the zenith and on their correlations with each other.