Hi everybody !
My name is Audrey. I am 23 years old and I am currently following a Master’s degree in Astronomical and Space-based Systems Engineering. As of this year, I have been working on the CubeSat with a classmate for the first time. Our study was on the functional analysis of BIRDY’s navigation function. It was a very rewarding task.
Today, I am conducting my Master’s final internship at the IMCCE in Paris. Here, I am studying a trajectory calculation method for an Earth-Mars-Earth free return for the CubeSat BIRDY. Thanks to a host trajectory, I will be able to provide a reference trajectory for the ephemerides of BIRDY and other planets. But first and foremost, we must know whether a return to Earth after the Mars flyby is possible at all !
Initially, it will be useful for the flight software and the generation of visual fields. This is why it seems necessary to agree on the interfaces.
I have mainly used Celestlab, but also SPICE to create Earth and Mars ephemerides. For the moment, I have created a trajectory from Earth to Mars by using the Lambert’s Problem (see the picture : the earth ephemeris in blue, the mars ephemeris in red, the CubeSat's trajectory in black). But in reality, the “patched conics” method has been of great use. It consists of approximating the trajectory Earth-Mars-Earth with conical sections. In fact, These movements are then reduced to two-body problems. Within the Earth’s sphere of influence, we will notice a geocentric hyperbolic orbit. Then, it will reach a heliocentric elliptic orbit, before approaching Mars’ sphere of influence, where it will be a Mars centered hyperbolic orbit. Eventually, it will adopt another heliocentric elliptic orbit until its return to Earth’s environment.
Subsequently, I will not consider the planets as perfect spheres. I
will also take into account the J2 of the Earth and Mars, which defines
their flattening, and which may have an impact on the CubeSat’s nearby trajectory.
I hope that you will all have fun taking part in this project!