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Elke's avatar

Mind blown again! Great post 👍

Corona Studies's avatar

" The higher you are the LESS the Gravitational pull, obviously, so you do not need to achieve extra speed to escape Gravity."

Rockets do not escape Earth's gravity by flying high. The reduction in gravity at 200 miles altitude is negligible (as far as staying up is concerned). Rockets don't escape gravity, they just ensure the fall back to Earth never happens by accelerating away from Earth at the same rate as the fall towards it.

If you fall 1000 ft you will hit the ground in around 10 seconds. But if you are travelling horizontally at 5000mph you will hit the ground a little later because the Earth has curved away from you by a small amount. If you increase that speed to 17,000 mph you will never hit the ground because the Earth curves away from you at the same rate that you are falling.

That's why rockets need to fly horizontally (perpendicular to the ground) and at high speed (around 17,000 mph) to maintain orbit. They are not escaping gravity, they are accelerating away from Earth at the same rate that they are falling towards Earth... hence they maintain the same altitude above Earth AKA 'orbit'.

To come back to Earth they just need to decelerate a bit. To fly off to the stars (or move to a higher orbit) they just need to accelerate a bit.

"It is not necessary to travel at 11km/s to escape the Earth's Gravity, as any speed will do, as long as you keep going up. "

They are not escaping Earth's gravity in LEO. This is your fundamental confusion and why it doesn't make sense to you.

If you built a skyscraper 200 miles high it would still have gravity as normal on the top floor (just a bit lower). If you dropped a brick off the top floor it would still fall to Earth.

But if you threw the brick horizontally at 17,000mph it would travel away from the Earth at the same rate as it falls towards Earth, thus it would remain in orbit at 200 miles altitude. It would 'fall' all the way around the Earth and come back to meet you from the other side where you could catch it like a boomerang.

Astronauts on the ISS are not weightless because there is no gravity up there. They are weightless because they are constantly falling (like people in an elevator with a snapped cable).

Your picture of the rocket launch making the shape of a rainbow shows the rocket disappearing over a hill. Except the hill is the curvature of the earth. Throw a ball off a hill and it will take longer to hit the ground because the hill curves away from you. The Earth is a perpetual hill (a globe) which is why launching a rocket horizontally with enough speed means it will never hit the ground. It just keeps going 'over the hill'. That's all an orbit is. The lack of air resistance at 200 miles up means the ball does not slow down and can keep going round and round.

After launching from Florida rockets hit Western Africa which is why they often pass over the 'Eye of the Sahara' which is a very obvious landmark. They do not drop into the sea. Only the ejected stages do which is what your photos show.

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