A COFFEE CUP FOR THE SPACE STATION

On earth, we pour the coffee in a cup and drink it without any effort. "Drinking coffee' works smoothly because of earth's gravity, but in space, in the absence of gravity, the liquid misbehave or stay put.

Say, a astronaut wants to drink coffee. Let us also assume that there is some coffee in a cup. (even pouring liquid in a cup is impossible in zero gravity). The man takes the cup and brings it close to the mouth. Suppose he gives some shakes to the cup, a little coffee may go into his mouth. The remaining coffee may go all over his face and the body.

In zero gravity, every thing stays still or moves in random directions. If forces are given on them, the things behave unpredictably. Hence, even 'sipping a coffee' is a task in the space station. It is solved by designing a coffee cup based on the principle of 'capillary action'.

What is capillary action? Take a glass tube of narrow width, say 0.5 mm and put in a beaker containing water. the water will rise to some height in the narrow tube automatically. The tube is called capillary tube and the action is called capillary action.

The 'capillary action' is due to 'surface tension' of liquid. The surface tension is due to inter molecular forces. The inter molecular forces are due to positive and negative charges in the atoms. Thus you have learnt in the school.

Weather the capillary tube is vertical or horizontal, in any way, the liquid will flow into it. Today, home kit for sugar test is available in the market. The blood flow into the 'test trip' due to capillary action.
Coming to our space coffee cup; the specially designed cup is curved on one side, sharply meet on the other side; makes a 'v' shape. The bottom is comparable to a capillary tube. When one puts a liquid coffee in it, the coffee will run through the narrow channel in the 'V' cup even in zero 'g'. Hence one can easily sip the liquid from the cup. (Care is taken in handling all the fluids in the international space station) . Since the cup is open one, the astronauts and cosmonauts can feel and smell the aroma of the tea and coffee and can get earth like experience.

FOOT NOTE: Fountain pen for the ink flow, candle for liquid wax flow, capillaries in our bodies for the blood flow, capillaries in the plant for the water flow. All these defy gravity and use 'capillary action' for raising the liquid.
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