Author Topic: Steam beta (2) - about orbital mechanics  (Read 1738 times)


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Steam beta (2) - about orbital mechanics
« on: February 02, 2018, 01:06:27 PM »
Two key points about planets and orbital mechanics:

1. As for mobile version, the planets are not well positioned. For Apollo 8 launch scenario (1968/12/21 12:51 UTC) we should have the following heliocentric longitudes (rounded to nearest degree):
Mercury: 296
Venus: 24
Earth: 89
Mars: 173
Jupiter: 174
Saturn: 24
Uranus: 181
Neptune: 236
The positions we get in the Orbit view are completely different.

2. The way you compute current spacecraft position in orbit has a flaw when it comes to accelerate time. The more you accelerate time, the more the orbit is deformed. It is especially annoying when putting CSM in a low lunar orbit, with perilune around 10km for instance. If we accelerate time, the perilune decreases until reaching 0 or even negative values. I think you will agree that this is not realistic. Even with some gravitational interference, an orbit so near to the moon should only depend on lunar attraction, and remain stable on duration, at least for a few orbits. This remark is applicable to Steam and mobile version as well.

My advice (but I don't know to what extend it could be done) would be to switch from an n-body to a pure, simple keplerian orbit when the user choses to accelerate. This way the step-by-step prediction would be exact as the keplerian movement is deterministic in essence.
« Last Edit: February 04, 2018, 11:28:22 AM by pclaurent »