Dark Side Transit Calculator

[blorgon]

https://www.geogebra.org/m/UMnrHYCX

Calculates the absolute longest possible* dark side transit time of a spacecraft for user-specified orbital characteristics in a prograde orbit that is 0° inclined relative to the planet's orbital plane (not the planet's equator).

Instructions: use the slider to select the planet, input your apoapsis and periapsis, click animate to see the satellite move!

* The absolute longest possible transit is one in which the orbit is 0° inclined relative to the planet's orbital plane, and the apoapsis is directly in the middle of the shadow. Due to the nature of the software I used to make the calculator, including inputs for argument of periapsis and longitude of ascending node was, practically speaking, impossible.

In the case of inclined orbits (on either the semi-major, or -minor axis), well, just know you’ll have some buffer. The added complexity in programming Geogebra to be able to handle the rotations (consistently) wasn’t worth the effort, especially with how many weird bugs in the software I encountered.

One last note: I haven’t added moons yet, but since your spacecraft’s longest transit will be through the planet’s shadow as the moon orbits it, and not the moon’s shadow, you can just input your apoapsis as the altitude of the moon’s orbit around the planet, if that makes sense. If not, I can draw a diagram!

Edited January 2, 2017 by blorgon