ootk/dist/utils/create-covariance-from-tle.js

Orbital Object Toolkit including Multiple Propagators, Initial Orbit Determination, and Maneuver Calculations.

import { Tle, CovarianceSample, CovarianceFrame, StateCovariance } from '../main.js';
/**
 * Creates a 6x6 state covariance matrix from a TLE
 * @param tleLine1 The first line of the TLE
 * @param tleLine2 The second line of the TLE
 * @param frame The covariance frame (CovarianceFrame.ECI or CovarianceFrame.RIC)
 * @param sigmaScale Scaling factor for the sigmas (default: 1.0)
 * @returns A StateCovariance object containing the 6x6 covariance matrix
 */
export function createCovarianceFromTle(tleLine1, tleLine2, frame = CovarianceFrame.RIC, sigmaScale = 1.0) {
    // Parse the TLE and get the state vector
    const tle = new Tle(tleLine1, tleLine2);
    const temeState = tle.state;
    const j2000State = temeState.toJ2000();
    // eslint-disable-next-line no-console
    console.log('J2000 State:', j2000State);
    /*
     * Determine appropriate sigma values based on TLE
     * These are rough estimates and can be adjusted based on your needs
     */
    const positionSigma = 1.0 * sigmaScale; // km
    const velocitySigma = 0.001 * sigmaScale; // km/s
    // Create a diagonal covariance matrix with sigma values
    const sigmas = [
        positionSigma, positionSigma, positionSigma,
        velocitySigma, velocitySigma, velocitySigma,
    ];
    // Generate the covariance matrix in the desired frame
    return StateCovariance.fromSigmas(sigmas, frame);
}
/**
 * Creates a sample-based covariance from a TLE with more realistic uncertainties
 * @param tleLine1 The first line of the TLE
 * @param tleLine2 The second line of the TLE
 * @param frame The covariance frame (CovarianceFrame.ECI or CovarianceFrame.RIC)
 * @returns A StateCovariance object
 */
export function createSampleCovarianceFromTle(tleLine1, tleLine2, frame = CovarianceFrame.RIC) {
    // Parse the TLE and get the state vector
    const tle = new Tle(tleLine1, tleLine2);
    const temeState = tle.state;
    const j2000State = temeState.toJ2000();
    /*
     * Create initial covariance with basic sigma values
     * Position uncertainties are higher in-track than radial/cross-track
     * for most space catalog objects
     */
    const sigmas = frame === CovarianceFrame.RIC
        ? [0.12, 1.0, 0.1, 0.00012, 0.001, 0.0001] // RIC frame: [R,I,C,Rdot,Idot,Cdot]
        : [0.6, 0.6, 0.6, 0.0006, 0.0006, 0.0006]; // ECI frame: [x,y,z,vx,vy,vz]
    const covariance = StateCovariance.fromSigmas(sigmas, frame);
    // Create a covariance sample that will be used to generate a more realistic covariance
    const sample = new CovarianceSample(j2000State, covariance, tle);
    // Return the desample in the appropriate frame
    return frame === CovarianceFrame.RIC ? sample.desampleRIC() : sample.desampleJ2000();
}
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