10. The surface and interior of venus

Present ideas about the surface and interior of Venus are based on data obtained from (1) Earth-based radio and radar: temperature, rotation, shape, and topography; (2) fly-by and orbiting spacecraft: gravity and magnetic fields; and (3) landers: winds, local structure, gamma radiation. Surface features, including large basins, crater-like depressions, and a linear valley, have been recognized from recent ground-based radar images. Pictures of the surface acquired by the USSR's Venera 9 and 10 show abundant boulders and apparent wind erosion.On the Pioneer Venus 1978 Orbiter mission, the radar mapper experiment will determine surface heights, dielectric constant values and small-scale slope values along the sub-orbital track between 50°S and 75°N. This experiment will also estimate the global shape and provide coarse radar images (40–80 km identification resolution) of part of the surface. Gravity data will be obtained by radio tracking. Maps combining radar altimetry with spacecraft and ground-based images will be made. A fluxgate magnetometer will measure the magnetic fields around Venus.The radar and gravity data will provide clues to the level of crustal differentiation and tectonic activity. The magnetometer will determine the field variations accurately. Data from the combined experiments may constrain the dynamo mechanism; if so, a deeper understanding of both Venus and Earth will be gained.     

The influence of space flight factors on viability and mutability of plants.

The experiments with air-dried Crepis capillaris seeds aboard the Soyuz 16 spaceship and the orbital stations Salyut 5, 6, 7 have revealed an increase in the frequency of aberrant cells in seedlings grown from flight-exposed seeds during the flight (experiment) and after the flight on Earth (flight control) as compared to the ground-based control. The increase in seedlings grown during the flight is more significant than in the flight control. During the flight Arabidopsis thaliana developed from cotyledons to the flowering stage. Analysis of seeds setting on these plants after the flight has shown a reduction in the fertility of these plants and an increase in the frequency of recessive mutants ("Light block-1"). An increased frequency of mutants was also retained in the progeny of plants which had passed through a complete cycle of development during the flight ("Fiton-3"). Suppression of embryo viability was observed in all experiments and expressed itself in reduced germinating ability of seeds from the exposed plants and in the early death of seedlings. Damages resulting from chromosome aberrations are eliminated in the first postflight generation and damages resulting from gene mutations and micro-aberrations are preserved for a longer time.     

Current sheets in the solar atmosphere

The 2D and 3D numerical simulation is used for the investigation of current sheet (CS) creation above the active region. The current sheet in the solar corona can be created either in vicinity of a magnetic field singular line by focusing disturbances or at the interaction of the super-Alfvenic plasma flow with the perpendicular magnetic field.     

Atmospheric drag modelling for orbital micro-debris at LEO altitudes

Data from satellite impact experiments and the scanning of recovered spacecraft offers an extended timebase to examine, using a consistent methodology, the microparticle fluxes. New penetration data from the TiCCE experiment on Eureca /1, 2/ adds to this database and shows that - despite an expected growth in the micro-debris flux - the observed flux is not greater than either LDEF or SMM. The question arises: “is this consistent with the micro particle flux being dominated by space debris or by meteoroids”.

To assist this assessment, numerical modelling using the Gear method /3/ of explicit time integration of the atmospheric drag lifetime of micron dimensioned orbital debris in both circular (LEO) and eccentric (GTO) orbits has been performed for the relevant space exposures. Results are applied to the data to examine whether the recent variations in flux can be attributed to varying levels of, orbital micro-debris caused by atmospheric drag and its changes during the solar cycle.     

Influence of Microgravity on Self-Propagating High-Temperature Synthesis of Refractory Inorganic Compounds

The self-propagating high-temperature synthesis was applied for the production of foam materials under the conditions of microgravity aboard the Mirstation. The materials obtained have a porous bimodal structure. The results of space experiments predicted using the interpolation method are checked. An unpredicted phase separation of the combustion products is discovered. The autowave combustion of suspended nickel-clad aluminum solids is observed for the first time. The combustion products were found to have a frame structure.     

Blood and clonogenic hemopoietic cells of newts after the space flight.

Ribbed newts were used for studying the effect of space flight on board of the biosatellite (Cosmos-2229) on blood and clonogenic hemopoietic cells. In blood of newts of the flight group, the relative proportion of neutrophils increased, whereas that of lymphocytes and eosinophils decreased. Space flight did not result in loss of the ability of newt blood cells to incorporate H3-thymidine. Analysis of clonogenic hemopoietic cells was performed using the method of hemopoietic colony formation on cellulose acetate membranes implanted into the peritoneal cavity of irradiated newts. To analyze reconstitution of hemopoiesis after irradiation donor hemopoietic cells from flight or control newts were transplanted into irradiated newts whose hemopoietic organs were investigated. The newt can be considered an adequate model for studying hemopoiesis under the conditions of the space flight.     

Le silence éternel de ces espaces infinis?

During the last 40 years — the merest blip in world history — talk about Homo astronauticus has signalled a growing awareness that the passengers on planet Earth can, if they want, take off for other destinations. If the scale of past advances is a satisfactory measure of future possibilities, then the wish will be father of the achievement.     

An approach to geometric reasoning in robotics

Anticipating the use of knowledge-based expert systems for robot task planning, a geometric reasoning is envisioned for the representation and manipulation of geometric information in a manner uniform with other knowledge. The general requirements for such a reasoner are outlined and a proposed architecture is described, built on four concepts: a class structure of spatial sets, features as subsets of those spatial sets, geometric abstractions as partial representations of features, and constraints as a mechanism for reasoning. An example implementation is built in an object-oriented environment and uses an underlying solids modeler, transparent to the end user     

Modeling of the radiation exposure during the flight of the second Bulgarian cosmonaut on board the Mir Space Station.

An experiment involving active detection of space radiation was carried out in the Space Research Institute (SRI) of Bulgarian Academy of Sciences, in preparation of the flight of the second Bulgarian cosmonaut. The radiations that would be encountered on the flight were modelled including solar and galactic cosmic rays and the particle radiation in the Earth's radiation belts. The dose rate was calculated for these different radiations behind the shielding of the space station. The variations in dose rates over the period of the flight were calculated and compared with measurements made during the orbit of the Mir Space Station. The calculated and measured dose rates agreed within 15-35%.