https://github.com/yuricst/polaris
PythOnLibrary for AstRodynamIcS
https://github.com/yuricst/polaris
Last synced: 11 months ago
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PythOnLibrary for AstRodynamIcS
- Host: GitHub
- URL: https://github.com/yuricst/polaris
- Owner: Yuricst
- License: mit
- Created: 2020-10-13T08:17:18.000Z (over 5 years ago)
- Default Branch: main
- Last Pushed: 2023-03-02T19:45:58.000Z (over 3 years ago)
- Last Synced: 2025-02-08T14:18:33.294Z (over 1 year ago)
- Language: Python
- Size: 7.66 MB
- Stars: 8
- Watchers: 2
- Forks: 2
- Open Issues: 0
-
Metadata Files:
- Readme: README.md
- License: LICENSE
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README
# polaris
polaris --- PythOnLibrary for AstRodynamIcS
[](https://pypi.org/project/astro-polaris/)
polaris is a Python library for preliminary spacecraft trajectory design.
The full documentation can be found [here](https://astro-polaris.readthedocs.io/en/latest/?). <--! in development! -->
### Installation
Install via pip
```bash
pip install astro-polaris
```
or clone this repository with
```bash
$ git clone https://github.com/Yuricst/polaris.git
```
### Dependencies
Core dependencies are
- `numba`, `numpy`, `pandas`, `scipy`
Although not necessary to run polaris, the following packages are also used within the example scripts and Jupyter notebooks:
- `tqdm`, `plotly`
### Imports
Subpackages within `polaris` are imported as
```python
import polaris.SolarSystemConstants as ssc
import polaris.Propagator as prop
import polaris.R3BP as r3bp
import polaris.Keplerian as kepl
import polaris.Coordinates as coord
import polaris.LinearOrbit as lino
```
For examples, go to ```./examples/``` to see Jupyter notebook tutorials.
### Quick Example
Here is a quick example of constructing a halo orbit in the Earth-Moon system. We first import the module
```python
import numpy as np
import matplotlib.pyplot as plt
import polaris.Propagator as prop
import polaris.R3BP as r3bp
```
Define the CR3BP system parameters via
```python
param_earth_moon = r3bp.CR3BP('399','301') # NAIF ID's '399': Earth, '301': Moon
param_earth_moon.mu
```
We construct an initial guess of a colinear halo orbit at Earth-Moon L2 with z-direction amplitude of 4000 km via the Lindstedt*–*Poincaré method
```python
haloinit = r3bp.get_halo_approx(mu=param_earth_moon.mu, lp=2, lstar=param_earth_moon.lstar,
az_km=4000, family=1, phase=0.0)
```
We then apply differential correction on the initial guess
```python
p_conv, state_conv, flag_conv = r3bp.ssdc_periodic_xzplane(param_earth_moon, haloinit["state_guess"],
haloinit["period_guess"], fix="z", message=False)
```
We finally propagate the result
```python
prop0 = prop.propagate_cr3bp(param_earth_moon, state_conv, p_conv)
```
and plot the result
```python
plt.rcParams["font.size"] = 20
fig, axs = plt.subplots(1, 3, figsize=(18, 8))
axs[0].plot(prop0.xs, prop0.ys)
axs[0].set(xlabel='x, canonical', ylabel='y, canonical')
axs[1].plot(prop0.xs, prop0.zs)
axs[1].set(xlabel='x, canonical', ylabel='z, canonical')
axs[2].plot(prop0.ys, prop0.zs)
axs[2].set(xlabel='y, canonical', ylabel='z, canonical')
for idx in range(3):
axs[idx].grid(True)
axs[idx].axis("equal")
plt.suptitle('L2 halo')
plt.tight_layout(rect=[0, 0.01, 1, 1.03])
plt.show()
```
We can also construct the manifolds of this halo orbit; consider for example the case of constructing its stable manifold
```python
mnfpls, mnfmin = r3bp.get_manifold(param_earth_moon, state_conv, p_conv, tf_manif=5.0,
stable=True, force_solve_ivp=False)
```
we can now plot
```python
plt.rcParams["font.size"] = 20
fig, ax = plt.subplots(1,1, figsize=(12,8))
for branch in mnfpls.branches:
ax.plot(branch.propout.xs, branch.propout.ys, linewidth=0.8, c='deeppink')
for branch in mnfmin.branches:
ax.plot(branch.propout.xs, branch.propout.ys, linewidth=0.8, c='dodgerblue')
ax.set(xlabel='x, canonical', ylabel='y, canonical', title='Stable manifold of the L2 halo')
plt.grid(True)
plt.axis("equal")
plt.show()
```
