Re: Orbits. How do they work?
« Reply #351 on: October 17, 2020, 10:04:08 PM »
Quote from: markjo on October 17, 2020, 08:55:24 PM
Quote from: Heiwa on October 17, 2020, 04:00:58 PM
The Moon orbits the Earth in one plane and direction since millions of years. It has more or less constant speed but the direction changes all the time.
The moon travels in at a constant speed a circle centered on the earth. It's not that hard to predict where it's going to be at any given time.
Quote from: Heiwa on October 17, 2020, 04:00:58 PM
Your spacecraft is in another orbit around Earth with variable speed and direction after take off.
The spacecraft speed varies based on known influences such as the gravitational influences of the earth, moon and sun, as well as the thrust applied by the rocket engine.
Quote from: Heiwa on October 17, 2020, 04:00:58 PM
If you think that you can blast off from a rotating Earth and arrive at the Moon, when it passes by at 1011 m/s in a known direction and that you can adjust your direction and speed so you can land, you are simply mistaken.
Why am I wrong? The rotation of the earth doesn't really matter. Why is it so hard to control my speed and direction and speed in space? It's not as if NASA and the Soviets didn't practice a number of times with unmanned orbiters and landers before risking human moon missions.
Thanks for asking.
Taking off from a rotating planet Earth affects your departure velocity and direction. You really have to take off at the right time in the right location.
Your departure time affects the location of your target (the Moon).
Your own speed/direction will vary all the time due to gravity, etc.
But OK - you do it in two steps. First step is to move into high speed LEO. And in LEO, second step, you blast off to the Moon at the right location, time, direction, etc, in LEO. Your speed increases from 7000 to 11000 m/s which takes time. How do you do this trans lunar injection move?
And then, third step, you are in a modified orbit that will bring you to the Moon. You leave Earth LEO behind and fly away. Speed is reduced all the time and your direction is also changed and then the Moon is coming in sight. It moves at 1011 m/s in another direction. There are many trajectories to chose.
Say that your arrival speed is 1011 m/s at 90° vertically towards the Moon. You are still orbiting Earth. What is step FOUR?
You brake hard and land? Not possible!
So you somewhere else (location, time, speed, direction unknown in Earth orbit) you start orbiting the Moon! But how? At one moment you are orbiting Earth and then, suddenly, you are magically orbiting the Moon. But how?
Pushing a button and your onboard computer takes care of it automatically. Your spacecraft rocket pushes you from one orbit to another?
And the Soviets did it. ROTFL! They just produced propaganda lies all the time. Still do!
Let's face it. There is no way to leave an Earth orbit and start orbiting a Moon in it's 1011 m/s speed orbit around Earth.