Category Science

How an astronaut’s spacesuit is made?

One of the weirdest features in space travel is the spacesuit worn by astronauts, with its huge spherical helmet, the tunic, the bulky gloves and boots and all the various gadgets and fittings.

The space-suit is a highly perfected machine in itself. It consists of no fewer than fifteen layers of special materials to protect the body of the astronaut. The space suit must provide oxygen for the astronaut to breathe and protect the astronaut from the vacuum and heat or cold of space. It must also be flexible enough to allow the astronaut to move freely. For travel in space, the astronaut wears an MMU (manned maneuvering unit), which contains small gas-powered thrusters. 

The space-suit must also contain food and water supplies, fitting to dispose of bodily wastes and surface to deflect heat and radiation. The helmet visor requires protective tilters to prevent the astronaut from viewing the Sun directly and risking severe dazzling and retinal burns. The suit also has to be fireproofed to the maximum possible extent.

The space-suit took years and millions of dollars to develop.

 

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When and how the fist steam engines were built?

The invention of the steam engine during the eighteenth century had a fundamental effect on man’s progress. Some earlier forms of this machine had appeared during the previous century. The most famous were those of papin whose work provided a great stimulus for research into steam.

Papin built a boat with steam operated paddles, but builders of sailing boats were hostile to this new craft and papin could not make much progress with it. However, he had proved what a powerful force steam could be in locomotion. Thomas newcomen built a steam engine in 1705. It began to be used for pumping water out of mines about six years later, and by 1725 the engine was widely used in collieries. It continued in use for many years although it was not very efficient and worked slowly. It was James watt (1736-1819) who examined all the previous efforts and perfected them into a steam engine that worked fast and efficiently. For this engine watt invented a steam condenser that was separate from the cylinder which worked the piston.

The steam engine had a sensational success and proved itself enormously useful, especially in factories where it replaced machines that had previously been worked by water or animal power. It was eventually used as a locomotive to pull wagons.

 

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By whom the electric light bulb was born and how?

Thomas Edison had discovered in his experiments that there were certain bodies through which electric power flowed more easily. He called these good conductors and other bodies that resisted the flow of electric power he called bad conductors. When electricity tried to travel along a bad conductor the latter would resist so much that it glowed until became white-hot.

A carbon filament, for example, gave out a good deal of light; but the light did not last very long because the carbon would soon burn itself up as it was in contact with the oxygen in the air.

Edison then carried out an experiment inside a glass bulb from which he had removed all the air. This time the light of the glowing filament lasted much longer and the fist electric light bulb was born.

Carbon filaments have now been replaced by tungsten wire as its high melting point, low rate of evaporation and low electrical consumption make it most suitable for use in light bulbs. A further improvement has been the introduction of an inert gas in to the bulb. This was at first nitrogen but is now a mixture of 88 per cent argon and 12 per cent nitrogen.

 

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When the barometer was born and how it works?

 Even air has weight and, like any solid object, it presses down on the surface of the Earth. Scientists decided to measure the amount of his pressure and the Italian Galileo was the first to succeed. He used a very long tube, closed at one end, which he filled with water and then placed the open end in a receptacle full of water. The water in the tube fell, stopping at a height of 10 meters. A few years later, in 1643, a pupil of Galileo named Evangelista Torricelli carried out further experiments using a heavier liquid than water; mercury. The mercury rose inside its tube, closed at one end, which he filled with water and then placed the open end in a receptacle full of water. The water in the tube fell, stopping at a height of 10 metres. A few years later, in 1643, a pupil of Galileo named Evangelista Torricelli carried out further experiments using a heavier liquid than water: mercury. The apparatus was given the name barometer from, the Greek baros meaning ‘weight’ and metron meaning ‘measure’. Torricelli soon noticed that the height of the mercury column varied with changes in air pressure. About 1647 Blaise Pascal’s experiments finally convinced people of the correctness of Torricelli’s ideas.

The most modern form of this instrument is the aneroid barometer, from Greek a meaning ‘without’ and neros meaning ‘liquid’. The aneroid barometer consists of a small steel box which contains a vacuum. The pressure of the air outside the box can cause the surface of the box to move in or out. A needle on the dial records the movements of the box along a graduated scale to show the changes in air pressure.

This type of barometer is smaller and more portable than a mercury barometer but it is not quite as accurate. It has first to be calibrated or set to a mercury barometer before it can be used.

 

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Did fish live in the desert?

Although it is difficult to believe, there are fish living in the desert. Several important expeditions have gone to the Sahara to uncover the mystery of these fish which are sometimes found scores of metres down.

The most famous is the lungfish which in the larger African rivers. When these rivers overflow their waters can spread out to desert regions to form small lakes or ponds. When the lake dries up the lungfish buries itself in wet mud where it can live for months on end, especially if it goes deep enough to find an underground layer of water.

Lungfish are among the most ancient bony fishes and are very like those which lived 200 million years ago, at the beginning of the Mesozoic Era.

 

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How the date palm manages to live in the desert?

There is a Bedouin saying which states that a date palm must have ‘its feet in water and its head in the sun’. for this reason the date palm is a typical tree of the desert oases.

Its roots dig very deeply into the soil until they find an underground store of water which gives rise to an oasis, that island of water and vegetation in the vast wastes of the desert. The palm needs a great deal of sunshine to grow vigorously and this explains the second part of the Bedouin saying.

A fully grown date palm tree stands more than 20 metres high. It has a slender trunk with a tuft of leaves at the top. Under these leaves there grow clusters of flowers which produce the berries that we know as dates. They have a sweet flesh and contain only one seed. A single larger branch of the tree may carry more than 1,000 dates weighing about 10 kilogrammes.

The date palm is very important in the life of desert people. This is not just because of its fruit but for every part of the tree. The wood from the trunk is used in building; the leaves are dried and make thatch roofs for huts as well as mats and ropes; the sap of the tree can be made into an alcoholic drink; and the seeds or stones of the date can be ground to make a beverage like coffee.

Date sugar, which is produced in India, is obtained from the sap of the Phoenix Sylvester’s, which is closely related to the date palm.

 

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