Developing a technique to enhance durability of fibrous ion-exchange resin substrate for space greenhouses.

One way to cut consumables for space plant growth facilities (PGF) with artificial soil in the form of fibrous ion-exchange resin substrate (FIERS) is on-board regeneration of the used medium. After crop harvest the procedure includes removal of the roots from the fibrous media with preservation of the exchanger properties and capillary structure. One type of FIERS, namely BIONA-V3ۛ, has been used in Russian prototypes of space conveyors. We describe a two-stage treatment of BIONA-V3ۛ including primary microwave heating of the used FIERS until (90 ±â€¯5) °C in alkali-peroxide solution during 3.5 hrs. The second stage of the treatment is decomposition of root vestiges inside pores of BIONA-V3ۛ by using thermophilic and mesophilic anaerobic bacteria Clostridium thermocellum, Clostridium cellulolyticum and Cellulosilyticum lentocellum during 7-10 days at 55 °C. The two-stage procedure allows extraction of 90% dead roots from the FIERS' pores and the preservation of root zone hydro-physical properties. A posterior enrichment of the FIERS by minerals makes BIONA- V3ۛ reusable.

Advanced nutrient root-feeding system for conveyor-type cylindrical plant growth facilities for microgravity.

A compact and reliable automatic method for plant nutrition supply is needed to monitor and control space-based plant production systems. The authors of this study have designed a nutrient root-feeding system that minimizes and regulates nutrient and water supply without loss of crop yields in a space greenhouse. The system involves an ion-exchange fibrous artificial soil (AS) BIONA-V3(TM) as the root-inhabited medium; a pack with slow-release fertilizer as the main source of nitrogen, phosphorus, and potassium; and a cartridge with granular mineral-rich ionite (GMRI) as a source of calcium, magnesium, sulfur, and iron. A controller equipped with an electrical conductivity meter controls the solution flow and concentration of the solution in the mixing tank at specified values. Experiments showed that the fibrous AS-stabilized pH of the substrate solution within the range of 6.0-6.6 is favorable to the majority of crops. The experimental data confirmed that this technique allowed solution preparation for crops in space greenhouses by means of pumping water through the cartridge and minimization of the AS stock onboard the space vehicle.

[Promising technique of mineral supply organization for plants in the condition of microgravity].

The proposed system of automated nutrient solution preparation for plant cultivation in microgravity consists of an ion-exchange fabric artificial soil (AS) as a root-inhabited medium, a pack with slow release fertilizer as the main source of nitrogen, phosphorus and potassium and a cartridge with a granular mineral-rich ionite as a source of calcium, magnesium, sulphur and iron. Experiments proved that fabric AS BIONA-V3 is capable to stabilize pH of the substrate solution within the range of 6.0 to 6.6 favorable to the majority of vegetable cultures. The experimental data attested suitability of this technique of water forcing through mineral-containing packs to automate nutrient solution preparation for crops cultivated in space greenhouses, and to minimize the stock of fabric AS onboard the space vehicle.

[Development of a minerals supply system for plants in a conveyor-type space greenhouse].

The paper presents ideas of optimizing the mineral nutrition system for salad crops in a space greenhouse. Experiments showed that to use mineral-saturated fiber ionite BIONA-V3 as an artificial soil will require to upmass a lot of expandable materials because of low specific content of nutrients. An additionally mineralized fiber soil makes possible to reduce mass of ionite in 5.6 times and volume in 28 times. The proposed mineral supply system is composed of two enrichment catridges with granulated ionite BIONA-V3 and slow-releasing fertilizer Osmocote 114-14-4, and a controller of irrigation water electric conduction stabilizer. Tests showed that this system provides sufficient mineral nutrition to plants and can be recommended for in-flight testing.

[Methods of extending the resource of fiber ionite artificial soils in space greenhouses].

The vegetable cultivation technology developed in view of long-term autonomous missions is based on root nutrition provided by fiber artificial soils (AS) containing ion-exchange resins. Useful life of ASs is limited by two factors which are nutrients depletion in ion-exchanger and clogging of the AS threshold space by roots remnants. Purpose of the investigation is to try out hydrolysis and ensuing microbial decomposition of roots remnants as a way to extend the resource of used fiber ionite AS. This principle of doing away with the roots remnants recovers almost completely the maximal water-absorbing capacity of AS BIONA-V3 so that it can be used again for crops cultivation.

[Results of salad machine experiment within the MARS-500 project].

The salad machine experiment was aimed to fulfill performance testing of a prototype of space conveyor-type cylindrical greenhouse PHYTOCYCLE-SL, to study growth and development of plants, and to evaluate microbial contamination of equipment in the closed manned environment. Crops of leaf cabbage Brassica chinensis L., cultivar Vesnianka were raised in the time interval between MARS-500 days 417 and 515. The greenhouse proved it serviceability demanding 17 min/(man x d) in the normal mode. Most likely that the slow growth rate and deviations in plant morphology were caused by the presence of volatile pollutants in the greenhouse compartment Accumulation of micromycetes was observed at the sites of humid surfaces contact with ambient air; reduction of the artificial soil area contacting with air decreased population of micromycetes in 40 times. Cabbage leafs were free of pathogenic microflora. These results of the experiment helped develop recommendations on how to work out some units and systems in projectable greenhouse VITACYCLE-T