Satellites and Space Travel


What are the vehicles used for space travel called?

Spacecraft or rockets.

What is re-entry?

The return of a spacecraft to Earth from space through the atmosphere is called re-entry.

What is a spacecraft heat shield?

During re-entry, some parts of the spacecraft may get heated up or even melt due to air friction, if they are unprotected. Vulnerable parts of a spacecraft are therefore protected by a heat shield made of special materials that can withstand the heat.




What is the difference between a jet plane and a rocket?

A jet plane carries only fuel onboard and no oxygen, since it absorbs oxygen from the air for burning its fuel. A rocket carries both fuel and oxygen onboard and is capable of travelling outside the atmosphere.





How can rockets fly in space?

A rocket moves due to the reaction created by the gases escaping from its engines and not due to any aerodynamics. The exhaust gases ejected by a rocket engine cause the rocket to move in a direction opposite to that of the exhaust gases.

What is the countdown period?

The countdown period is the time taken from the time the order is given for launching the rocket to the time it actually gets launched. During the period, an elaborate prescribed procedure is followed for checking and putting into operation various mechanisms connected with the launching of the rocket and may even last for a week. The last twenty-four hours of countdown is referred to as the final phase of countdown. The last few seconds of the final countdown period are usually announced on the public address system as“……. five, four, three, two, one, ZERO”. Zero refers to the moment of launching.




What are the different types of fuels used in rockets?

Rockets use solid or liquid propellants. However, for sustained propulsion over very long periods in space, nuclear propulsion is preferable.

What is lift off?

Lift off refers to the point, a few seconds after launching when the thrust from the rocket engines attains a level where it exceeds the total weight of the rocket. At this stage, the rocket literally begins to lift off the ground.




What are the liquid fuels used in a rocket?

The commonly used liquid rocket fuels are liquid are liquid hydrogen, nitrogen tetroxide, kerosene etc. Rockets also carry liquid oxygen required for combustion of the fuel. Liquid fuel rockets are commonly used for launching rockets from Earth into space which calls for larger initial thrust. Liquid hydrogen and liquid oxygen are also called cryogenic fuels since they arre stored at extremely low temperatures.


How much fuel does a rocket need to carry on board?

The speed of the rocket will increase if its engine is kept running for a longer period. Hence, the amount of fuel carried by the rocket will depend on the speed which it is required to achieve. For example, a rocket with an empty weight of 1 tonne will need to carry about 1.75 tonnes of fuel to reach the speed of its exhaust gases and about 19 tonnes of fuel to reach three times the speed of its exhaust gases.

What are splashdown and touchdown?

Splashdown is the moment a space vehicle or capsule lands in the ocean after completing its mission in space. If it comes down on land it is called touchdown.







What is a multi-stage rocket?

In a multi-stage rocket specific sections or stages of the rocket are jettisoned or discarded in flight to lighten the load. The rocket is therefore specially constructed in detachable parts to enable such multi-stage operation. A multi-stage rocket is more efficient than a single stage one and can reach much higher speeds. Depending on the number of stages, they may be designated as two-stage, three-stage, etc.