Traveling and Working in Space

Transcription

1 Traveling and Working in Space Read the information provided in Traveling and Working in Space. Decide if each statement below is true or false. Write the word in the blank before each statement. If the statement is false, explain why it is false on the space provided after the question. If the statement is true, leave that space blank. 1. Spacecraft are often painted white on the outside and black on the inside. 2. A spacecraft must be light and strong. 3. The atmosphere on a spacecraft can be much different from Earth s. 4. Solid wastes that are produced while in space are ejected out into space. 5. If the pressure inside the spacecraft is not correct, the blood and heart can be affected. 6. Plenty of water is loaded into the spacecraft before it takes off. 7. You feel like you weigh something only because of Newton s 3 rd Law. 8. If you were in space without a suit, your blood could boil. 9. Spacesuits keep the body fluids in a gaseous state of matter.

2 10. Spacesuits can be compared to plastic wrap. 11. Heat produced by an astronaut s body can cause trouble. 12. Space dust passes by astronauts continually, but is not harmful. 13. Astronauts wear sunglasses. 14. Astronauts cannot bend their arms or legs when wearing their spacesuits. 15. Someday, humans may vacation in space.

3 Traveling and Working in Space adapted from Photo courtesy NASA Space shuttle Endeavour (STS113) in orbit as seen from the International Space Station. A launch vehicle s engines can lift a certain amount of weight into orbit. The weight is divided into two parts. The weight of the vehicle itself (including the fuel) and the weight of the passengers and other equipment the spacecraft is carrying. This can be an incredible amount of weight. Engineers try to keep the structure of the spacecraft as light as possible. But designing a light craft is difficult because it also must be very strong. There is a tremendous push of the engines during lift off in order for the spacecraft to overcome earth s gravity. This push can cause the spacecraft to fall apart. So the materials must not only be light, but strong. Once off the ground, the spacecraft requires additional energy. This additional energy is needed because the spacecraft will have resistance to the air. The space shuttle has foam insulation that protects it from the friction caused by the air resistance. It also has silica glass fiber tiles to protect it from heat. Scientists and Engineers use white paint, shades, and reflectors to help cool a spacecraft. Usually, the inside components are painted black to radiate heat more efficiently. Inside the spacecraft, the pressure, air, water, temperature, and waste must all be controlled for the safety of the crew and spacecraft.

4 Life Aboard Spacecraft (like the Shuttle) The spacecraft must provide you with an environment similar to Earth. You must have air, food, water, and a comfortable temperature. The orbiter must also take away the wastes that your body produces (carbon dioxide, urine, feces) and protect you from fire. On board the space shuttle, you need to have the following: atmosphere similar to Earth carbon dioxide and other gases removed normal humid environment Our atmosphere is a mixture of gases (78 percent nitrogen, 21 percent oxygen, 1 percent other gases) that we breathe in and out. The space shuttle must provide a similar atmosphere since space is a vacuum and there is no air. To do this, the orbiter carries liquid oxygen and liquid nitrogen. These gases are circulated by fans. As the astronauts breathe in the circulated air, they breathe out carbon dioxide. The carbon dioxide is absorbed by chemicals on the space craft and removed. The food on the spacecraft must be nutritious and healthy. Food is stored in the crew compartment. Food comes in several forms (dehydrated, low moisture, heat-stabilized, irradiated, natural and fresh). The orbiter has a galley-style kitchen which has food warmers and utensils. Just like your home, the spacecraft must be kept clean. Wastes from cleaning, eating, working and personal hygiene must be contained. Trash is separated into wet trash bags and dry trash bags, and the wet trash is placed in an evaporator that removes the water. All trash bags are stowed in the lower deck to be returned to Earth for disposal. Solid waste from the toilet is compacted, dried and stored in bags where it is returned to Earth for disposal (burning). Liquid waste from the toilet goes to the wastewater tank where it is dumped overboard. Humans must be enveloped by the right temperatures and pressure. The temperature of outer space varies drastically. Therefore the space vehicle is equipped with a temperature control system to maintain the temperature. A lack of pressure causes changes in the cardiovascular system, the muscular-skeletal system and the nervous system. To overcome this problem airtight enclosures or capsules where appropriate pressure can be artificially maintained must always surround the astronauts.

5 Water 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 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 exhaled air. The recycled water is mostly used for washing purposes. Personal Needs: Eliminating body wastes - Due to the micro gravity, collection and disposal of body wastes pose a huge problem. A device resembling a toilet seat is used for the collection of wastes. Airflow provides suction for the 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. Bathing - The simplest way of bathing is a sponge bath with the help of wet towels. A collapsible shower stall is also used where water is sprayed on the astronaut's body. The stall is dried by a vacuum. Sleeping - Sleeping bags with pillows are used to fasten the astronauts to a soft surface. Astronauts may wear blindfolds to block sunlight. Some astronauts prefer to float in air with only a few straps fastened to prevent bouncing. Recreation - To refresh the mind, the space station has collections of books, computer games and tapes. Exercise also helps the mind to relax. Weightlessness - Why is it that a person feels his/her own weight? The answer is very simple. It is due to the earth's gravity. The earth's pull exerts a force on the body, and by Newton's third law, there is an equal and opposite force back on the earth. This gives us the feeling of weight. If gravity is not present, then we get a feeling of weightlessness. This is what happens when we go into space. The feeling of weightlessness does not have any drastic effect on humans, as long as it is for a very short period of time. If weightlessness is experienced for a long time, there can be some injury to the body (in the form of muscle loss). Space Water

6 Life Outside of the Spacecraft Outer space is a very hostile place to people. There is very little or no air pressure or oxygen. A space suit allows man to go into space. If you were to go out into space without a suit, these things could happen: You would be unconscious in 15 seconds Your blood and body fluids would boil and freeze The skin, heart and other organs would expand The temperature in the sunlight can get to 248 o F and in the shade, -148 o F Exposure to radiation You could be hit by particles of dust or rock which move at very high speeds and can tear a suit. By creating an Earth-like environment within the suit itself, spacesuits allow humans to walk around in space in relative safety. Pressurized Atmosphere The spacesuit provides air pressure to keep the fluids in your body in a liquid state -- in other words, to prevent your bodily fluids from boiling. Like a tire, a spacesuit is essentially an inflated balloon that is restricted by some rubberized fabric, in this case, Neoprene-coated fibers. The restriction placed on the "balloon" portion of the suit supplies air pressure on the astronaut inside, like blowing up a balloon inside a cardboard tube. Oxygen Spacesuits cannot use normal air percent nitrogen, 21 percent oxygen and 1 percent other gases -- because the low pressure would cause dangerously low oxygen concentrations in the lungs and blood, much like climbing Mt. Everest does. So, most spacesuits provide a pure oxygen atmosphere for breathing. Spacesuits get the oxygen either from a spacecraft via an umbilical cord or from a backpack life support system that the astronaut wears. Carbon Dioxide The astronaut breathes out carbon dioxide. In the confined space of the suit, carbon dioxide concentrations would build up to deadly levels. Therefore, excess carbon dioxide must be removed from the spacesuit's atmosphere. Spacesuits use special canisters to remove carbon dioxide. Temperature To cope with the extremes of temperature, most spacesuits are heavily insulated with layers of fabric (Neoprene, Gore-Tex, Dacron) and covered with reflective outer layers (Mylar or white fabric) to reflect sunlight. The astronaut produces heat from his/her body, especially when doing strenuous activities. If this heat is not removed, the sweat produced by the astronaut will fog up the helmet and cause the astronaut to become severely dehydrated. To remove this excess heat, spacesuits have used either fans/heat exchangers to blow cool air, as in the Mercury and Gemini programs, or water-cooled garments, which have been used from the Apollo program to the present. The special fabrics of the space suit also protect the astronauts from collisions with micrometeoroids (small particles of dust and rock). These layers also prevent the suit from tearing on exposed surfaces of

7 the spacecraft or a planet or moon. The space suits offer limited protection from radiation. Some is offered by the reflective material, but wouldn t help if there was a solar flare. Seeing and Communicating Spacesuits have helmets that are made of clear plastic or durable polycarbonate. Most helmets have coverings to reflect sunlight, and tinted visors to reduce glare, much like sunglasses. Also, prior to a spacewalk, the inside faceplates of the helmet are sprayed with an anti-fog compound. Finally, modern spacesuit helmet coverings have mounted lights so that the astronauts can see into the shadows. The spacesuit is equipped with radio transmitters/receivers so that spacewalking astronauts can talk with ground controllers and/or other astronauts. The astronauts wear headsets with microphones and earphones. Mobility Moving within an inflated spacesuit is tough. Imagine trying to move your fingers in a rubber glove blown up with air; it doesn't give very much. To help this problem, spacesuits are equipped with special joints, or tapers, in the fabric to help the astronauts bend their hands, arms, legs, knees and ankles. In weightlessness, it is difficult to move around. If you push on something, you fly off in the opposite direction (remember Newton's third law of motion?). Therefore, spacecraft are equipped with footholds and hand restraints to help astronauts work in microgravity. In addition, before the mission, astronauts practice spacewalking in big water tanks on Earth. Photo courtesy NASA Astronauts training in water for a spacewalk to build the International Space Station It isn t easy traveling and working in space. But, new technologies are being developed all of the time. Someday, humans may even be able to vacation in space!!