Define minimal altitude

[ACH1980]

Feature Request

Is your feature request related to a problem? Please describe.
When rendezvousing a very low orbit the orbit often get's dropped below dangerous limits (atmo for example, not sure if the script respects for terrain or if it would crash into that also)

Describe the solution you'd like

Define atmosphere and terrain limits as minimal altitude per default and allow the user to overwrite the default.

Describe alternatives you've considered

Let only the user define minimum altitude without automatic defaults.

Additional context

I thought this only happens by approaches from below, but it also affects approaches from higher orbits to lower orbits.