Grade six science

Posted: October 19, 2011

Meeting basic needs in Space. All missions require living in hostile environment of space. Therefore certain basic needs have to be fulfilled to provide astronauts with environment similar to that of earth.These include:•  Breathing - Space is a vacuum and there is no air out there. For the survival of human beings a suitable composition of air is required. A continuous supply of oxygen is essential for respiration. A manned spacecraft uses a gas, which is a combination of oxygen and nitrogen. This gas is circulated with the help of fans in the cabin. •  Pressure - human body must be enveloped by appropriate pressure .The lack of pressure causes changes in the cardiovascular system, the musclo-skeletal system and the nervous system. To accomplish this problem airtight enclosures or capsules where appropriate pressure can be artificially maintained must always surround the astronauts.•  Temperature control - the temperature of outer space varies drastically. Therefore the space vehicle is equipped with a temperature control system to maintain the temperature. The functions carried out by the system are:•  Distribute the heat evenly•  Get rid of the excess heatThe temperature aboard the spacecraft is maintained by active methods and passive methods.•  Active method involves the circulation of fluid to remove heat•  Passive methods use insulating materials and electrical heaters•  Eating and drinking - the food given to astronauts must be nutritious, easy to prepare and should not be perishable. Modern spacecrafts are equipped with facilities for heating frozen foods. Food comes in several forms (dehydrated, low moisture, heat-stabilized, irradiated, natural and fresh). The orbiter has a galley-style kitchen module, which is equipped with the following:Food storage compartmentsFood warmersA food preparation area with warm and cold water outletsMetal trays so the food packages and utensils do not float awayWater is an essential requirement. Water is made from liquid oxygen and hydrogen      In the space shuttle's fuel cells. The fuel cells can make 25 lb (11 kg) of water per hour. The water from the fuel cells passes through a hydrogen separator to eliminate any trapped hydrogen gas. Excess hydrogen gas is dumped overboard. The water is then stored in four water storage tanks. On a long mission water must be recycled and reused. Dehumidifiers are used to extract moisture from the exhaled air. The recycled water is mostly used for washing purposes.•  Eliminating body wastes - due to the micro gravity, collection and disposal of wastes poses a huge problem. A device resembling toilet seat is used for the collection of wastes. Airflow provides suction for collection of wastes under the toilet seat. On small aircrafts funnels are used for collection of liquid wastes and plastic bags are used for solid wastes. While working in space special equipments are worn for collection of wastes.