About space and spacecraft

Exploring the space and its infinite mind-boggling mysteries has been man’s quest for centuries dating back to prehistoric days. It was infact, the attempt to know the facts about the celestial bodies in the skies, that man learnt to think, guess, imagine and come up with hypothetical answers which eventually took shape of religions, faiths, blindfaiths and philosophical theories. Later, the scientists took up the challenge to research on space to provide the authentic and tested facts.
They succeeded to a great extent. All the space missions are part of that endeavour to know the truths about the cosmos step by step leaving no scope for any doubt. The scientists are looking for signs of life in any conceivable form on other planets of the solar system or on the planets of other stars. There are encouraging signs of the presence of water at one time or other on other planets and of life supporting gases. The real discovery can be made only by sending manned or unmanned space crafts to these planets. Unmanned space craft and space stations are the stepping stones in the direction of space exploration.
Walking or staying in the space is a challenging task. There the things are opposite to what we have on earth. The body floats in weightlessness and the space is airless vacuum.
The space craft lifts up fighting off the mighty gravitational pull down of the earth. And it is required to follow a pre-determined path to stay on course and in contact. It also helps in keeping the gravitational effect to the minimum.
Extremely powerful booster rockets take the space craft or satellite to the space, consuming an enormous amount of fuel for lift up against gravitation of earth. Several rockets or stages of a rocket burn one by one to do the task of keeping up momentum. After burning, the rockets detach and fall off. The space craft keeps zooming up on the power of the burning rockets until all the rockets fall off after taking the payload to the destination. Then, the satellite or the space craft is on its own powered by its own resources provided.
Another problem of space craft is the rocket fuel. As the rocket distances from earth it enter zones with less and lesser air density having diminishing proportion of oxygen. The fuel requires oxygen to continue the burning process. To slove this problem rocket fuel is injected with liquid oxygen which makes it a dangerous mix.
Take off of a space craft is difficult but the re-entry into earth atmosphere and landing is still more tricky, problematic and dangerous. The real danger begins an hour before the landing when it becomes very difficult to reduce the speed of the space craft.
When the space craft re-enters the earth’s stratosphere air particles in very dense state hit the front part of the craft creating intense friction resulting in red hot plasma enveloping the craft surface having a temperature between 50000C to 55000C. That temperature is more than that of sun’s outer surface. To save the craft from such extreme heat it is covered with a shield of quartz fibres. Refrigeration process is also used to cool the outer craft cover from inside. Any malfunction of these two processes can spell a fiery doom for the space craft.
While re-entering the earth atmosphere due to air resistence the front part of the space craft gets lifted up exposing the belly of the craft which comes into contact with intensely hot air particles (plasma). So the belly is protected with layers of high heat resistant stuff like China clay sheets or mica chips. It is a very vital safety cover without which the space craft would melt and burn to ashes in quick time.
The space craft banks at 40 degree in the atmosphere, this position is technically called ‘Angle of attack’. While take off, orbitting or re-entering the stratosphere the aircraft meets extreme heat, far below freezing point cold, radiation, magnetic waves and there also is danger of its being hit by debris of old satellites or meteors, comets and any loose space matter flying. Even a pea size object hitting the craft can create the effect of a bomb and shatter it to pieces.
To safe guard from these dangers the space craft is made of two walls. The outer wall absorbs all the impacts of any small object hitting it. The inner wall escapes the damages of minor kind.
The inside of the space craft also poses several problems—one is that of increasing temperature. The electric or electronic gadgets and the bodies of the crew release heat increasing the temperature inside. To cope with this problem refrigeration system is used. Cold liquid chemical is pumped in through coils and heat is transferred to the outside radiator.
Another great discomforter and inconvenience is weightlessness. Due to absence of the gravity the passengers and loose items float around in the air. To direct liquid fuel in the desired direction very high pressure gases have to be employed.
Even air has to be circulated with special type of fans. Inside dust particles and the molecules of the moisture stay at the suspended particles. The fans put them in correct position.
A Space Shuttle is a reusable space craft. It can be used several times over. Its booster rocket section is non-reusable. Shuttle is a half aeroplane and half rocket or the combination of both. It can put satellites in the orbit and bring back gadgets or satellites from space. It also can repair damaged satellites.
The space shuttle has three distinct sections:
1. Outer fuel tank
2. Crew cabin
3. Solid rocket boosters
1. Outer Tank—It is the largest section of the shuttle that can only be used for one take off. Outer tank is shuttle system’s big power house. It is designed to fit in the requirements and the objective of the space shuttle. O.T. consists of three main sections—Liquid Oxygen Tank, Hydrogen Tank and Inter-tank Assembly.
2. Crew Cabin—It is situatied in the front portion of the orbiter in two-tier setup. It can accommodate a crew of two to eight astronauts. From this cabin the crew operates and guides the flight of the shuttle or space craft. It is a kind of control room. In the frontal part sit the Mission Commander and the pilot with flight control system penals around them. In the rear part sit Mission Specialists with Remote Manyolator system. In the left side of the cabin has ‘Mission Operation Display’ and the right side is Payload Control.
3. Solid Rocket Boosters—Before the launch, two solid rocket boosters stand erect on the launch pad bolted to the pad structure. The space shuttle and Outer Tank are strapped to it. That is how the entire system travels to the sky. The first, Outer Tank separates when its fuel is used up. Then the solid rocket boosters fall off the shuttle.

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