T. Ivanova

Microgravity effects on water supply and substrate properties in porous matrix root support systems

The control of water content and water movement in granular substrate-based plant root systems in microgravity is a complex problem. Improper water and oxygen delivery to plant roots has delayed studies of the effects of microgravity on plant development and the use of plants in physical and mental life support systems. Our international effort (USA, Russia and Bulgaria) has upgraded the plant growth facilities on the Mir Orbital Station (OS) and used them to study the full life cycle of plants. The Bulgarian-Russian-developed Svet Space Greenhouse (SG) system was upgraded on the Mir OS in 1996. The US developed Gas Exchange Measurement System (GEMS) greatly extends the range of environmental parameters monitored. The Svet-GEMS complex was used to grow a fully developed wheat crop during 1996. The growth rate and development of these plants compared well with earth grown plants indicating that the root zone water and oxygen stresses that have limited plant development in previous long-duration experiments have been overcome. However, management of the root environment during this experiment involved several significant changes in control settings as the relationship between the water delivery system, water status sensors, and the substrate changed during the growth cycles.

First results of the Bulgaria-1300 satellite experiment

Abstract The satellite “Intercosmos-Bulgaria-1300” launched on 7 August 1981 is successfully working already more than a year. Aboard the satellite a Bulgarian scientific research complex is mounted for studying the ionosphere, magnetosphere and their mutual relations, containing 12 different instruments and systems. Below, the first results of the direct investigation of the higher atmosphere by means of different systems and instruments is presented in short: graphically we have given the distribution of the ion density obtained by processing of data obtained from one orbiting of the satellite; the optical complex working aboard Bulgaria-1300 is briefly described. The basic characteristics of the optical apparatuses are given. The optical axes of the two photometers EMO-5 and PHOTON-1, which are part of the optical complex, are orientated in nadir. UV-spectrometer works in a spectral region of 1150–2550 A with a spectral solution of 10 A. Each 3.5 min there is a spectrum of the daytime or nighttime atmosphere. These data can be used for aeronomic investigations of the higher atmosphere dynamics as well as for determining ozone. As an example of joint work and interpretation of the data from different groups of Bulgarian research devices working aboard the Bulgaria-1300 satellite, the energy deposition in the polar ionosphere as determined by measurements aboard the satellite is given.