Author Topic: spacecraft staying in orbit  (Read 32422 times)


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spacecraft staying in orbit
« on: April 10, 2018, 11:12:17 AM »
From time to time we'll get a question similar to the one below:
when I put myself in orbit around a planet and I accelerate time, the orbit change itself and I'm no longer in orbit".

The reason why it seems that you're going off orbit is because there are two types of orbits simulated in this game. The yellow orbit is the analytic orbit. This is the idealised orbit that we're all used to seeing in textbooks. These are usually circular or oval shaped orbits that wrap neatly around the planet. The is what an idealised orbit. This is how an orbit would look like if there were only the planet and the spacecraft in the entire space.

Of course, there are other celestial objects in the Universe and in the game. The actual path of the orbit is not as neat. It is affected by all the other objects in the space, albeit, to a much smaller extent.

To see the actual or real orbit that your spacecraft will take, you need to look at the pink orbit. This orbit is calculated numerically and represent that path your spacecraft will actually take. More often than not, this will always deviate from the yellow path.


1) We try to go to the Moon. We adjust Delta-V and Delta-T until the yellow analytic orbit extends beyond the Moon. 

2) But we know for sure that the path that your spacecraft will travel won't be that simple. To see the REAL path of the spacecraft, hit the COMPUTE button to calculate the path numerically. You will see a pink path calculated. This the more like the actual path that a spacecraft would travel in this situation.

3) Here we see that the pink path is too short and we don't see what happens around the Moon. To see further into the future we simply increase the Sim Step slider to extend the calculation further.

In this image, we see clearly how the two orbits differ and how orbits will shift over time due to the presence and movement of other gravitational bodies in the simulated space and other factors, such as changing mass, etc.
« Last Edit: April 11, 2018, 06:11:16 AM by ApolloGirl »