pious_squid

Description:

pious squid

pious_squid #
An astrodynamics library for the Dart ecosystem, covering orbital mechanics
and satellite mission analysis logic.
Features #

Celestial Bodies

Earth
Moon
Sun


Coordinates

Classical Orbital Elements
Equinoctial Elements
Geocentric Celestial Reference Frame (GCRF)
Geodetic Coordinates
International Terrestrial Reference Frame (ITRF)
J2000 Inertial Frame (J2000)
Relative Frame (RIC/EQCM)
True Equator Mean Equinox Inertial Frame (TEME)
Two-Line Element Set (TLE)


Covariance

Covariance Sigma Sampling/Desmpling


External Data

Earth Orientation Parameters
Space Weather


Perturbation Forces

Atmospheric Drag (Harris-Priester)
Earth Gravity (up to 70x70 geopotential)
Solar Radiation Pressure
Spacecraft Thrust
Spherical Body Gravity
Third Body Gravity (Sun and Moon)


Interpolators

Chebyshev Ephemeris Interpolator
Cubic-Spline Ephemeris Interpolator
Lagrange Ephemeris Interpolator
Verlet-Blend Ephemeris Interpolator


Maneuvers

Relative Waypoint Targeting
Two-Burn Transfer (Hohmann)


Metric Observations

Geocentric Right-Ascension and Declination (RaDec)
Optical Observation
Radar Observation
Range-Azimuth-Elevation (RAzEl)
State Observation (ITRF)
Topocentric Right-Ascension and Declination (RaDec)


Math

Matrix Operations
Quaternion Operations
Vector Operations


Optimization

Chebyshev Ephemeris Compression
Downhill Simplex (Nelder-Mead)
Gauss-Newton Differential Correction
Golden Section
Particle Swarm Optimization
Polynomial Regression
Simple Linear Regression


Orbit Determination

Batch Least Squares Orbit Determination (OD)
Gauss-Newton Orbit Determination (OD)
Gibbs Initial Orbit Determination (IOD)
Gooding Initial Orbit Determination (IOD)
Herrik-Gibbs Initial Orbit Determination (IOD)
Lambert Initial Orbit Determination (IOD)
Modified Gooding Initial Orbit Determination (IOD)


State Propagation

Dormand-Prince 5(4) Adaptive Numerical Propagator
Kepler Two-Body Analytical Propagator
Runge-Kutta 4 - Fixed Numerical Propagator
Runge-Kutta 8(9) Adaptive Numerical Propagator
Simplified Perturbations Model 4 (SGP4)


Data Smoothing

Exponential Smoothing (single/double/time)


Time

Barycentric Dynamical Time (TDB)
Global Positioning System Time (GPS)
International Atomic Time (TAI)
Terrestrial Time (TT)
Universal Coordinated Time (UTC)
UT1-UTC Time (UT1)



Usage #
import 'dart:io';

import 'package:pious_squid/pious_squid.dart';

void main() {
// Optionally, load Earth Orientation Parameter (EOP) data.
DataHandler().updateEarthOrientationParametersFromCsv(
File('external/EOP-All.csv').readAsStringSync());

// Optionally, load Space Weather (SW) data.
DataHandler().updateSpaceWeatherFromCsv(
File('external/SW-All.csv').readAsStringSync());

// Create a new J2000 inertial satellite state.
final startState = J2000(
EpochUTC.fromDateTimeString('2017-02-03T06:26:37.976Z'), // utc
Vector3D(-3134.15877, 7478.695162, 1568.694229), // km
Vector3D(-5.227261462, -3.7717234, 2.643938099), // km/s
);

// Define some spacecraft properties.
final massArea = 87.5; // kg/m²

// Create a perturbation force model.
final forceModel = ForceModel()
// Model a 36x36 geopotential.
..setEarthGravity(36, 36)
// Model Moon and Sun gravity.
..setThirdBodyGravity(moon: true, sun: true)
// Model solar radiation pressure, with reflectivity coefficient 1.2.
..setSolarRadiationPressure(massArea, reflectCoeff: 1.2)
// Model atmospheric drag, with drag coefficient 2.2.
..setAtmosphericDrag(massArea, dragCoeff: 2.2);

// Create a Runge-Kutta 8(9) propagator.
final rk89Prop = RungeKutta89Propagator(startState, forceModel);

// Propagate the start state to 1 day in the future.
final oneDay = 86400.0; // seconds
final finalState = rk89Prop.propagate(startState.epoch.roll(oneDay));

print(finalState);
// ->[J2000]
// Epoch: 2017-02-04T06:26:37.976Z
// Position: [5704.152590, -5470.867067, -3040.596164] km
// Velocity: [4.554130436, 4.557924086, -2.152201166] km/s

// Create a observer location.
final observer = Geodetic.fromDegrees(-15, 80, 0.05);

// Calculate look-angles from the observer to the satellite.
print(finalState.toITRF().toGeodetic());
final razel = Razel.fromStateVectors(
finalState, observer.toITRF(finalState.epoch).toJ2000());
print(razel);
// => [RazEl]
// Epoch: 2017-02-04T06:26:37.976Z
// Azimuth: 141.6525°
// Elevation: 60.3304°
// Range: 2318.580 km
}
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More examples can be found in the
example
directory.
External Data #
Some operations will will have lower fidelity or unexpected results if external
data is not loaded. External data can be found at:

Earth Orientation Parameters (EOP)

Last 5 Years: https://celestrak.org/SpaceData/EOP-Last5Years.csv
All: https://celestrak.org/SpaceData/EOP-All.csv


Space Weather (SP):

Last 5 Years: https://celestrak.org/SpaceData/SW-Last5Years.csv
All: https://celestrak.org/SpaceData/SW-All.csv



The scripts/update_eop_sw.sh will update the external data in this repo.
License #
Copyright (c) 2023 David RC Dayton

Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all
copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
SOFTWARE.
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