Gravity Power

 

newtonThe genius of Isaac Newton, who in the 17th  century defined gravity and produced a universal law of gravitation laid down the foundations for scientists, theoretical physicists such as Einstein.

Gravity Power

Gravity is pervasive, it affects and influences us all on our planet, in our solar system  and in our universe.

einstein1Astronomy is a hobby/interest of mine I like to learn all about what happens in the cosmos and how our space probes/telescopes are unlocking secrets preciously hidden to us.   Below Ben Gilliland excellently explains how gravity helps  push back the frontiers of space

WE ARE USED TO THINKING OF SPACE FLIGHT as a struggle against gravity. After all, it takes vast, towering rockets filled with hundreds of tonnes of explosive liquids and gases just to give a light-aircraft-sized vehicle enough thrust to break free of the bonds of Earth’s gravity.

Even if you are lucky enough make it into space, there are still endless gravitational hurdles to overcome. Contrary to what Sir Isaac Newton believed, gravity isn’t caused by two massive objects pulling on one-another. Instead, gravity is a by-product of the dents and distortions made by massive objects in the fabric of the Universe. A truly massive object, like a planet, makes a pretty big dent and, when a less massive object, like a spacecraft, strays too close it finds itself ‘falling’ into that dent – it might look as if the spacecraft is being ‘pulled’ towards the planet, but really it is ‘falling’ towards it.

The Solar System is littered with these gravitational pitfalls – a satellite falls towards the Earth, the Earth falls towards the Sun and, in turn, the Sun falls towards the centre of the Milky Way. The only way to stop this fall from becoming a direct plunge is to move through space fast enough to ensure your momentum keeps you aloft.

You can think of the Sun’s gravity as being a little like a wine glass. If you drop an olive into the glass, it will fall straight to the bottom, but, if you spin the glass, you can give the olive enough momentum to roll around the sides without falling in (like a planet orbiting the Sun). Decrease the momentum and its orbit will fall closer; increase it and its orbit moves further away. If you continue to increase the speed, eventually the olive will move so fast that it will achieve ‘escape velocity’ and fly from the glass.

A spacecraft leaving Earth has been given enough momentum to escape Earth’s gravity wine glass, but, if it wants to travel into deep space, it has to find enough momentum to escape the Sun’s gravitational dent. Using rockets isn’t practical because they’d need so much heavy fuel it would be prohibitively expensive to just leave the Earth –so scientists came up with a clever trick called a ‘gravity assist’ manoeuvre,

Also known as the ‘slingshot’ manoeuvre, the technique was first used successfully 40 years ago this week, by Nasa’s Mariner 10 Mercury probe. Instead of struggling against the gravitational pull of the planets, during a gravity assist, a spacecraft uses a planet’s gravity (or a series of planets) to give it a speed boost. By falling towards a planet that is falling towards the Sun, a spacecraft can ‘steal’ enough momentum to travel against the Sun’s gravitational pull.

So you could say that spaceflight isn’t flying at all: it’s just falling, with style.

 

 

A spacecraft leaving Earth has been given enough momentum to escape Earth’s gravity wine glass, but, if it wants to travel into deep space, it has to find enough momentum to escape the Sun’s gravitational dent. Using rockets isn’t practical because they’d need so much heavy fuel it would be prohibitively expensive to just leave the Earth –so scientists came up with a clever trick called a ‘gravity assist’ manoeuvre,

Also known as the ‘slingshot’ manoeuvre, the technique was first used successfully 40 years ago this week, by Nasa’s Mariner 10 Mercury probe. Instead of struggling against the gravitational pull of the planets, during a gravity assist, a spacecraft uses a planet’s gravity (or a series of planets) to give it a speed boost. By falling towards a planet that is falling towards the Sun, a spacecraft can ‘steal’ enough momentum to travel against the Sun’s gravitational pull.

So you could say that spaceflight isn’t flying at all: it’s just falling, with style.

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