Placing communications satellites in orbit is frequently demanded as a service by scientific establishments which pay for various experiments to be carried out in space. Industry provides the money to set up factories in space for special manufacturing processes designed to take advantage of the lack of gravity. Eventually, this will lead to the establishment of huge, permanently staffed space stations. Away from Earth’s gravity, one serious disadvantage for the astronaut is the body inability to produce calcium for the bones. Calcium loss can be as high as two per cent in a month. At that rate, a long space trip could permanently cripple a space traveller. For those carrying out a tour of duty at a space station, long periods of zero gravity would be intolerable. Therefore space stations will mimic Earth’s gravity. To do this, they will rotate, producing centrifugal force at the outside edge. A practical design for such a rotating model is a circular continuous cylinder, like a thin doughnut. A large, rotating, circular space station will provide Earth-like environment, which could be enhanced with plants and trees, and even water lakes.
On spaceships and small space stations, where it is not practicable to counteract the effects of zero gravity, simple functions such as eating and going to the lavatory create major problems. Unless care is taken when eating and drinking, lumps of food and globules of liquid will sail uncontrollably around the cramped living space. Early space food included meals in squeezed bags, which delivered nutritious sludges directly into the mouth via a tube. But these meals proved unpopular, so astronauts now have food that resembles what they would eat back on Earth. In zero gravity conditions, special devices are necessary to collect the astronaut ‘solid and liquid wastes’.
Space commodes are fitted with lap straps, as well as hand and food holds, to keep the astronaut clamped securely to the close-fitting seat. Air jets and air suction move solid wastes down into the chamber, where they are fragmented by a rotating metal blade. After being dried, the wastes are stored for later analysis. Urinating is achieved either via personal ‘relief tubes’ with different fittings for men and woman, or through a unisex fitted cup. Urine is vented out into space, where it flash freezes instantly into icy crystals. Sometimes the vented urine build up into bulky icicles, which have to be removed from the outlet port by means of an external robot arm. On both large stations and small spacecraft, water will need to be constantly recycled, for drinking and for reconstituting dehydrated foods. Filtrations plants will recycle water, urea and carbon dioxide from the space-travellers body waste to produce purified water and oxygen.
For long, unserviced flights, food will have to be synthesized in small micro-biological units. On a large space station, with artificial gravity and climates, food could be produced by growing plants. It would be more economic to grow the plants in solution of nutrient, rather than in soil. Animals would be relatively uneconomic to produce for food, although some could be reared to add variety to meals. Home-grown items would be good for moral, but would be expensive luxury.