How does the spaceships and satellites propell in space, as there is no madium?

Question

how can one move ahed in space, as he can not swim or take help of any support?

Answer 1

By using a simple law of physics... for every action there is an equal and opposite reaction

In other words if you have a rocket motor (for example) it will blast stuff out behind you and the equal and opposite reaction is to propel you forwards. Many future propulsion systems have been proposed that work on the same basic principle... laser light guns, streams of plasma, even setting off atomic explosions behind the spaceship.

Another possible means of propulsion is to use a "solar sail" - a huge umbrella-like structure which catches the solar radiation from the sun and acts like a sail pulling the spaceship along.

Answer 2

Ah! the New Yort Times argument. Rockets can't travel in space because there is no air against which the rocket exhaust can push.
http://en.wikipedia.org/wiki/New_York_Times#Famous_mistakes

Took to New York Times 49 years before they admitted their mistake.
"Further investigation and experimentation have confirmed the findings of Isaac Newton in the 17th century, and it is now definitely established that a rocket can function in a vacuum as well as in an atmosphere. The Times regrets the error."

It is a "centre of gravity" thing. Imagine that the rocket (and its fuel) is stopped in space. The centre of gravity is therefore not moving.

Fire some fuel out of one end. The centre of gravity of the fuel moves one way. However, the centre of gravity of the entire mass (rocket plus fuel) must stay in the same place. Conclusion: the centre of gravity of the rocket must move the other way to compensate.

Satellites, once in orbit, do not need to swim. They are moving sideways from the energy they got when they were put on orbit. From that point on, they are falling towards Earth, except that they are falling at exactly the same rate that the ground curves under them (the Earth being round). Therefore, the satellite is in constant free fall all around Earth.
In reality, Satellites in low orbits may need a small boost every once in a while, because there are still a few molecules of air here and there, and it is enough to slow them down a bit over long periods.
The international space station (almost 400 km above Earth's surface) needs to be boosted back up as it loses more than 150 metres a day -- approx. 10 km in a couple of months.

So, for satellites, "medium" is bad since it would slow them down and, eventually, cause them to fall back to Earth's surface.

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Astronauts (and cosmonauts) inside the Space Station, are falling at exactly the same rate as the Space Station. That is why they act like they were weightless. They can actually "swim" through the air inside the Station, pushing air one way with their hands can cause their bodies to move the other way. But that is not a very efficient way to get from place to place, because the mass of air being pushed back is very small compared to the mass of their bodies. It is much faster to push against walls and pull on well placed handles and handrails.

Answer 3

Space ships don't fly so much as get thrown. The rocket thrust from the rocket engine is basically like the recoil of a gun. The bullet goes very fast froward and the gun kicks backward more slowly. The gun pushes against the bullet and the bullet pushes against the gun, no air is needed. The molecules of exhaust gasses are like trillions of tiny bullets going out the exhaust nozzle and that pushes the rocket forward. But the rocket fuel run out in a few minutes and the rest of the time the space craft is just coasting with no control at all, under the influence of gravity and momentum, exactly like a bullet does after it leaves the gun.

Answer 4

Rockets work in space because of the laws of physics that says "blow something in one direction and the object will move in the other direction".
On earth, we're so used to pushing against something (like the land or water when we're swimming) that we don't realize that a rocket doesn't have to push against a medium to work.

Picture shooting a rifle - the bullet goes out the front and the rifle kicks back into your shoulder. If you weren't holding the rifle, the bullet would go shoot out the front anyway and the rifle would kick backwards anyway.

Answer 5

Stand on a skateboard and throw a shot put. You'd move backwards, wouldn't you? Not because of the air or the ground, but because you're pushing on the shot put ball. A rocket works the same way. It's pushing on the exhaust gas it throws out the back.

Answer 6

You don't need to push against a medium, but you DO need to expel mass. Action-reaction (Newton's theory) is what works here.

A person can't "swim" from one place in space to another, but if he had four or five bricks, he could throw them in one direction, moving him in the opposite direction.