About

The gravitas package has one primary goal: to provide lighnting fast acceleration vectors for satellite orbit propagation. It currently supports:

Model	Central Body	Maximum Degree/Order
EGM96	Earth	360
GRGM360	Moon	360

Setup

pip install gravitas

Example Usage

import gravitas
import numpy as np

r_ecef = np.array([[7000.0, 0.0, 0.0], [0.0, 7000.0, 0.0]])
# Define an [nx3] numpy array in Earth-Centered, Earth-Fixed (ECEF) coordinates [km]
g_vector = gravitas.acceleration(r_ecef, max_order=360, use_model="EGM96")
# Query the acceleration at these positions using a maximum degree/order of 360 and the EGM96 Earth gravity model
>>> [[-8.14574564e-03 -2.19120213e-08  3.01312643e-08]
     [-2.25445258e-07 -8.14546631e-03 -1.50901874e-08]]

Algorithm

Gravitas uses the normalized Pines' method, based on an implementation by DeMars. DeMars' implementation was translated from MATLAB into C++ and is imported as an extension.