[The problem of developing a lettuce greenhouse for the International space station and future interplanetary missions].

In order to evaluate the effects of gravity on growing plants, we conducted ground-based long-term experiments with dwarf wheat (cultivar "Apogee USU") and Chinese cabbage (cultivar "Khibinskaja"). The test crop had been grown in overhead position with HPS lamp below the root module so that gravity and light gradients were in opposite direction. Plants of the control crop grew in normal position under the same lamp. Both crops were grown on porous metallic membranes with stable--1 kPa water potential on the surface. Results from these studies allowed us to examine the significant differences in growth and development of the plants as well as the root systems in relation to the gravity force. Nevertheless, the experiments in greenhouse Svet aboard the Mir space station proved that it is possible to compensate the effects of weightlessness on higher plants by manipulating gradients of environmental parameters (i.e. photon flux, water potential in the root zone, etc.). Even in ground studies Svet productivity averaged no more than 14 gm of fresh salad biomass per a day. This does not provide a sufficient supplement nutrients to the ISS crew. A cylindrical design of a space plant growth facility (SPGF) allows for maximal productivity under very tight energy and volume limitations onboard the ISS and a number of operational advantages.