Quick Start Guide

This guide provides a basic walk-through of pyRTX to compute the Solar Radiation Pressure (SRP) on a spacecraft.

  1. Load SPICE Kernels

All calculations requiring geometry or astrodynamic data rely on the SPICE toolkit. You must provide a “metakernel” that lists all the necessary SPICE kernels (trajectory, attitude, clock, etc.).

import spiceypy as sp

METAKR = 'path/to/your/metakernel.tm'
sp.furnsh(METAKR)

  1. Define the Spacecraft

A spacecraft is defined by its components (bus, solar arrays, antennas), each with its own 3D model, reference frame, and material properties.

from pyRTX.classes.Spacecraft import Spacecraft

# Component models are stored in a dictionary
model = {
    'BUS': {
        'file': 'path/to/bus.obj',
        'frame_type': 'Spice',
        'frame_name': 'SC_BUS_FRAME',
        'center': [0.0, 0.0, 0.0],
        'diffuse': 0.1,
        'specular': 0.3,
    },
    'SOLAR_ARRAY': {
        'file': 'path/to/solar_array.obj',
        'frame_type': 'Spice',
        'frame_name': 'SC_SA_FRAME',
        'center': [0.0, 0.0, 0.0],
        'diffuse': 0.0,
        'specular': 0.3,
    },
}

# Create the spacecraft object
sc = Spacecraft(
    name='MySpacecraft',
    base_frame='SC_BUS_FRAME',
    spacecraft_model=model
)

  1. Set Up the Ray Tracing Environment

To calculate SRP, you need to define a source for the sun’s rays (a PixelPlane) and a RayTracer to track their paths.

from pyRTX.classes import PixelPlane, RayTracer

# Define the sun's ray source
rays = PixelPlane(
    spacecraft=sc,
    mode='Dynamic',
    distance=100,  # meters from spacecraft
    source='Sun',
    width=10,      # meters
    height=10,     # meters
    ray_spacing=0.01 # meters
)

# Configure the ray tracer
rtx = RayTracer(
    spacecraft=sc,
    pixel_plane=rays,
    bounces=1
)

  1. Calculate Solar Radiation Pressure

Finally, create a SolarPressure object and use it to compute the acceleration over a desired time range.

from pyRTX.classes import SolarPressure
from pyRTX.core.analysis_utils import epochRange
import numpy as np

# Define time settings
start_epoch = "2024 JAN 01 12:00:00"
duration = 3600  # seconds
step = 60      # seconds
epochs = epochRange(start_epoch, duration, step)

# Create the SRP calculator
srp = SolarPressure(
    spacecraft=sc,
    ray_tracer=rtx,
    baseflux=1361.5  # W/m^2
)

# Compute the acceleration [km/s^2]
acceleration = srp.compute(epochs, n_cores=1)

Next Steps