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Background
Background
As an intern at NASA Ames Research Center on the Flight Dynamics team, much of my work was centered around Astrodynamics, Trajectory Design, and the overarching study of Orbital Mechanics. In order to supplement and automate my trajectory design workflow, I created a calculator in MATLAB which calculates the initial orbit states for a Three-Body Periodic Orbit. This calculator reports initial position (X, Y, Z) and velocity (Vx, Vy, Vz) states for a periodic orbit in the three-body system. Ultimately, this MATLAB calculator is a supplementary add-on to the NASA JPL Three-Body Periodic Orbit Catalog and helps trajectory design engineers utilize given dimensionless data.
Description
Description
This MATLAB calculator takes inputs directly from NASA JPL's Three-Body Periodic Orbit Calculator and converts them into initial state vectors for orbits which can be modeled in simulation softwares such as Ansys STK, Copernicus, and NASA GMAT. In the JPL Catalog, a user can input their desired orbit system, family, libration point, and many other key factors which help to define a given orbit. The user can then take those dimensionless coordinates and calculate a usable, easy to read state vector.
Workflow Architecture
Workflow Architecture
User inputs desired orbit conditions using NASA JPL Three-Body Periodic Orbit Catalog
(Example: NASA's Lunar Gateway Orbit - L2 Southern Near Rectilinear Halo Orbit)
User generates a table of initial, dimensionless orbit states using NASA JPL Three-Body Period Orbit Catalog and selects desired orbit from the list. Given that the stability index of this selected orbit is exactly 1.000, it should theoretically be mostly stable in simulation.
User inputs dimensionless values for (x0, y0, z0) and (vx0, vy0, vz0) into MATLAB calculator and adjusts physical conversion properties for the system within the calculator. These physical conversion properties depends on the mass ratio of the two respective bodies (in this case Earth-Moon) and desired simulation software (every software has unique mass ratios for planetary bodies).
User outputs the state vector of initial conditions of desired orbit with its respective dimensions in an easy to read table. It is important to note that this state vector is with respect to the Earth-Centered Rotating Reference Frame with the reference axes being the Earth-Moon line through the L1 point.
This vector can then be propogated and visually modeled in the user's desired software (in this example, Ansys STK using the Astrogator Tool) with the use of a model spacecraft. This visualization is crucial as it gives a better understanding of potential target conditions in the user's overall trajectory design and helps piece together the end result of the desired orbit.
Input Conditions for Orbit
My Movie 38.mp43D View of Propogated Orbit using Initial State Vector
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