GeneralAstrodynamics.jl

Common astrodynamics calculations, with units!

JuliaCon Talk

Check out GeneralAstrodynamics in action at JuliaCon 2021! The talk Going to Jupiter with Julia walks through a simple Jupiter mission design while gently introducing astrodynamics, Julia, and GeneralAstrodynamics.

Features

Restricted Two-body Problem (R2BP)

Structures for Cartesian and Keplerian states, and R2BP systems
Functions which implement common R2BP equations
Kepler and Lambert solvers
Orbit propagation and plotting

Circular Restricted Three-body Problem (CR3BP)

Structures for dimensioned and normalized Cartesian states, and dimensioned and normalized CR3BP systems
Functions which implement common CR3BP equations
Analytical and iterative (numerical) Halo orbit solvers
Unstable and stable Halo orbit manifold computation
Orbit propagation and plotting
Zero-velocity curve computation and plotting

N-body Problem (NBP)

This was implemented in a previous package version, and is currently being refactored

Usage

Some quick examples are below!

# Installation
import Pkg
Pkg.add("GeneralAstrodynamics") # or julia> ]install GeneralAstrodynamics

# Loading
using GeneralAstrodynamics, Unitful

# Construct a R2BP orbit (massless spacecraft
# moving due to the gravity of one planet)
orbit = let e = 0.4, a = 10_000, i = Ω = ω = ν = 0, planet = Earth
    orbitalstate = KeplerianState(e, a, i, Ω, ω, ν)
    Orbit(orbitalstate, Earth)
end

# Alternatively, use a `CartesianState`
orbit = Orbit(
    CartesianState(randn(6)), # random state vector, [r..., v...]
    Earth
)

# Construct a CR3BP orbit (massless spacecraft moving
# due to the gravity of two planets, both of which
# move in a circle about their common center of mass)
orbit = Orbit(
    CartesianState(randn(6)), # random state vector (again!)
    SunEarth
)

# Propagate any orbit in time (after `using DifferentialEquations`)
using DifferentialEquations
trajectory = propagate(orbit, 10u"d") # unitful times are convenient here!

# Constract a periodic orbit within CR3BP dynamics (Halo orbit),
# and the orbital period `T` (also requires `DifferentialEquations`)
orbit, T = halo(SunEarth; L=1, Az=75_000u"km")

# Construct a manifold which converges to (stable), or
# diverges from (unstable) the Halo orbit
superslide = manifold(orbit, T; duration=2T, eps=-1e8, direction=Val{:stable})

# Plot any `Trajectory` or `Manifold` (after `using Plots`)
using Plots
plot(trajectory; title="R2BP Trajectory")
plot(propagate(orbit, T); vars=:XY, label="Halo Orbit", aspect_ratio=1)
plot(superslide; vars=:XY, title="Stable Manifold near Earth")

In the coming years, the Getting Started page will have code examples, and other documentation for fundamental astrodynamics concepts, and GeneralAstrodynamics usage. Stay tuned and/or submit pull requests!