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updated 7/23/2011 11:17:52 AM ET 2011-07-23T15:17:52

I know it's hard and you have to be really smart to be an astronaut, but I think I have what it takes.

I've read loads of books about it and I think have the Right Stuff. I was watching the preparation for the launch of STS-135 when shuttle Atlantis was about to become the final ever shuttle launch and it actually seems that the astronauts have it quite easy. They even had someone do up their seat belts! I've been getting people to do my seatbelt up in the car for me as training.

The real reason I fancy being a spaceman is that I would love to just float about up there. It sounds crazy. Seems like an easy life to me, I want in.

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Of course, the reality of life as an astronaut is somewhat different. Once in space, they face a whole range of challenges both physical and psychological. Not least must be the experience of weightlessness that is the one thing that everyone associates with space travel.

But before we understand what causes weightlessness in space -- or, more accurately "microgravity" -- a little bit of physics first.

Every object, with a few rather strange exceptions, has "mass." Effectively, mass is the term that defines how much matter makes up an object, and regardless of whether you are on Earth, floating in space or sitting at the core of mighty Jupiter, your mass will always be the same. It's a distinctly different term from the word that describes how heavy you are; your "weight." Weight is determined by acceleration (for example, gravity) with acting on your mass. So, on the moon, where there is less gravity than here on Earth, you will weigh less (but your mass stays the same).


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When you are in orbit around the Earth in a spaceship, it looks like you are floating. In reality, you're plummeting toward the Earth in free fall! It's probably worth explaining that a little more, so I need you to imagine throwing a ball horizontally.

Once the ball leaves your hand, it will follow a curved path down to the surface of the Earth as the gravity of Earth acts upon its mass. If you throw it harder, it will travel further, but it will still curve downward, ultimately hitting the ground.

Now, remember that the Earth is a sphere. If you could throw the ball hard enough, it would follow a curved path, falling toward the surface of the Earth but at the same time, and same rate, the surface of the Earth would be curving away from it. The ball would never land. If you were inside the ball then you would be falling at the same rate as the ball. You'd therefore appear to be 'floating' -- or technically, 'falling with style.'

This is exactly what happens to any object in orbit around another; from the shuttle in orbit around the Earth to the Earth in its orbit around the sun -- although the orbital dynamics of the planets are a little more complicated, but the principal is the same.

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If you've ever been brave enough to skydive, the experience and feeling would be akin to a sky dive that lasts for the duration of your time in orbit (without the rush of wind, of course). It must be one hell of an experience to be in 'free-fall' or weightlessness for a period of days, even weeks and months in some cases but it doesn't come without nasty side effects, least of which is muscles wasting away. Astronauts have very stringent exercise routines built into their schedule while in orbit to try and minimize adverse effects on their bodies.

Of course, getting a job as an astronaut does require incredible levels of physical fitness and mental ability, not to mention an iron cast constitution.

On second thoughts, perhaps it's not the job for me, after all, I've never seen any coffee shops in space.

© 2012 Discovery Channel

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