SPACE SHUTTLES

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Among robotic probes, shuttles also turn out to be a vital part of space transportation. Unlike earlier space vehicles, shuttles are reusable. They provide years of good service without replacement. Along with humans it can also carry huge payloads of satellites and scientific instruments. Even the building of space stations require tremendous help from shuttles. They are a major part of 21 'st century technology. Scientists are taking ideas based on shuttles to make much better advanced spacecrafts.

The shuttle has three basic parts : 1. Orbiter 2. Solid rocket boosters -165 feet long. Produce about 5.5 million pounds of thrust. 3. Fuel tank 155 feet long with 29 feet diameter. The orbiter and solid boosters are reusable, though the fuel tank is not. It breaks up in the atmosphere. The fuel tank carries liquid oxygen along with a chemical that would burn upon contact or with an igniter. The shuttle weighs about 20,00 tons when fully fueled. At least a speed 25,000 miles per hour is needed to escape gravity of earth.

  • The various parts of a shuttle orbiter are as follows: The orbiter consists of a payload bay, which is a large storage area for keeping cargo such as telescopes. The bay is about 60 feet long and 18 feet wide. Lately Russians have made a whole laboratory that fits inside the storage area of a shuttle. The payload bay also has radiators behind it. When the doors are open these radiators let out heat from the shuttle into space. A robotic arm in the bay helps to move cargo. In front of the bay is the flight deck. The orbiter is piloted from here. Controls for the robotic arm are also located here. Beneath the flight deck is the crew compartment. The crew can sleep, eat, work, communicate with earth as well as use the lavatory from here. This area also holds a personal hygiene center. Refrigerators and microwaves are kept in a small galley in the crew compartment. There are four beds as well. The astronauts can sleep in any position because there is no definite gravity in space. Astronauts often get sick with drowsiness, headaches, dimness and nausea because of weightlessness. So they exercise on a treadmill to keep themselves healthy. In space the heart grows smaller and the body grows taller. The orbiter provides an earthlike atmosphere. Astronauts can go about wearing loose jackets and pants. An appropriate pressure is maintained inside the orbiter for the astronauts. Water and electricity comes from a byproduct of hydrogen and oxygen. At least about 14 kilowatts of electricity is produced. The orbiter also has black boxes or avionics systems which are programmed to replace components with backup systems if they fail to work. The orbiter is protected with advanced fire detection systems. There are about 4 portable and 3 built in extinguishers.

    About 20,000 thermal tiles, each at least 3&1/2 inches thick, protect the orbiter from the intense heat of atmosphere. At the very back of the orbiter are the rockets. There are three SSMEs(space shuttle main engines.) These are the most advanced rockets ever made. They are liquid fueled and provide a lot of power. Yet they come use only during takeoff. The other two engines are OMS. (orbital maneuvering engines) They have nozzles, which can be turned to change direction of the orbiter. The speed can also be controlled. The shuttle orbiter uses these to guide itself around in space.

    Though the fuel in OMS usually gets used up before it re-enters the atmosphere after the mission is completed. Small thrusters on the nose and back of the orbiter are required to make minor changes in the orbiter's positioning. The orbiter uses large flaps on it's wings called elvons along with a body flap under the rockets, to maneuver itself while re-entering and landing. Shuttles come in many types. The best known is the one built by USA. The Soviet Union tried to make a similar model though with minor changes­ mainly that it's fuel tank is reusable unlike the US's. Europe has it's own version called Hermes. This is a rather smaller craft which would be placed on top a rocket and launched. Hermes will be reusable as well .While on the other side West Germany plans differently. They think of making a craft called Sanger which would be an orbiter placed over another booster craft and the two will take of together. Even the US thinks of making a new spacecraft called the airspaceplane. This vehicle will have the capability to fly at a speed of 12,500 km/hr without any added on rockets. People hope that in future shuttles will be able to take off from runways like normal airplanes on earth.

    Here is a description of a shuttle flight :
    1) The space shuttle is launched using two solid booster rockets along with three SSMEs from the launch pad.
    2) The two rockets are released from the craft at a height of about 45 kilometers. The rockets parachute down and fall into the ocean where they get picked up by a ship.
    3) As the shuttle escapes gravity , the fuel tank is discarded when it's almost empty. The tank breaks up in the atmosphere.
    4)The OMS are fired to propel the spacecraft into orbit.
    5) Astronauts perform experiments, release payloads and confirm other needed operations. Sunrise and sunset is seen within every 90 minutes.
    6) The orbiter heads back towards earth. It turns around and fires it's engines to slow down orbital speed. Then coming out of orbit, it gently curves downwards.
    7) It turns around again flying bottom first to absorb intense heat of the atmosphere. Tiles protect the craft and keep it cool.
    8)The orbiter's re-entry is completed about 55 km above earth. It glides down at a speed of 13,300 km/hr .
    9) The craft lands on the runway at a speed of 250 km/hr and uses it's rudder brakes along with a parachute to slow down.
    10) The orbiter is used again and the whole process starts over .

    COLUMBIA

    Columbia shuttle was launched by the US at 7:00 AM , April 12 ,1981 from Florida. There were two men on board. Commander John Young and pilot Robert Crippen. This was the shuttle's first flight. A test flight. The pilots tested all the orbiter systems successfully. They flew upside down in relation to earth. " Man that was one fantastic ride " exclaimed Crippen after landing. He was very excited. The orbiter landed 2 days and 4 hrs after takeoff. Touching down at California it landed at a speed of215 km/hr. The Columbia orbiter weighed 98 tons. On the morning of January 28 , 1986 , the Challenger shuttle was launched from Florida. It had a crew of seven. A school teacher was amongst them. It lifted off the ground and just 74 seconds later , exploded shooting out huge fumes. All seven were killed. Horror spread throughout the country as they saw the shuttle get blown into pieces. Millions who were disappointed paid respects to the astronauts. The deadly fireball struck like a nightmare. NASA tried to find the cause for the heartbreaking tragedy. There had been a failure in a joint around the right solid booster's motor. Despite some unfortunate failures NASA launched many other successful launches.

    People imagine that one-day colonies will be built. Hotels will be opened which will allow families to take vacation trips. Newspapers will say -Vacation for 4. All expenses included. Shuttle flight lifting off July 28. See you there.