- #1

- 4

- 2

## Summary:

- Vallado calculation to find shadow entry and exit points in an elliptical orbit.

## Main Question or Discussion Point

Hello fellow Space People,

Currently trying to create a function in MATLAB to input an R and V vector and have it spit out all the orbital elements as well as shadow entry/exit locations. I have the Vallado "Fundamentals of Astrodynamics" book and I've used it religiously. I searched on here and only found help with circular orbits. I have those totally figured out, however, with the code that is free online, for some reason, it will not work with elliptical orbits based on my modeling software.

There are a couple of bugs in it out the gate, I'm pretty sure I fixed most of them. I model the orbits in GMAT and they don't match what the MATLAB code is giving me. I calculate circular orbits with different code (Because it's easier) with the same sun position vector and it works. I calculated the sun position vector the way Vallado instructs. So I'm not sure where the disconnect is. Does anyone have experience with this kind of thing? Most of the literature I find all comes back to Vallado so I'm not sure if there's a better way.

Thanks guys.

Currently trying to create a function in MATLAB to input an R and V vector and have it spit out all the orbital elements as well as shadow entry/exit locations. I have the Vallado "Fundamentals of Astrodynamics" book and I've used it religiously. I searched on here and only found help with circular orbits. I have those totally figured out, however, with the code that is free online, for some reason, it will not work with elliptical orbits based on my modeling software.

There are a couple of bugs in it out the gate, I'm pretty sure I fixed most of them. I model the orbits in GMAT and they don't match what the MATLAB code is giving me. I calculate circular orbits with different code (Because it's easier) with the same sun position vector and it works. I calculated the sun position vector the way Vallado instructs. So I'm not sure where the disconnect is. Does anyone have experience with this kind of thing? Most of the literature I find all comes back to Vallado so I'm not sure if there's a better way.

Thanks guys.

Last edited by a moderator: