Determining satellite close approaches, part 2
Abstract
Improvements to the original Alfano/Negron Close Approach Software (ANCAS) tool are presented that increase accuracy and/or step size. Minimum spacing between two satellites is determined by creating a timedependent thirdorder relativevelocity waveform produced from adjoining pairs of distances, velocities, and accelerations. Times of closest approach are obtained by extracting the real roots of the localized polynomial with the associated distances reconstructed from a set of fifthorder polynomials. Close approach entrance and exit times for an ellipsoidal quadric surface are found using a similar process. Both methods require a simplified computation of acceleration terms of the objects of interest. For this study a close approach truth table is constructed using a 0.1 second sequential step along the orbits and differencing the two position vectors. The simulation results show this algorithm produces close approach times almost identical to those of the truth model for larger time steps (up to 10 minutes), with a corresponding reduction in computer runtime. The results are created from real orbital data and include solution sets for three operational uses of closeapproach logic. Satellite orbital motion is modeled by, but not limited to, firstorder secular perturbations caused by mass anomalies.
 Publication:

Journal of the Astronautical Sciences
 Pub Date:
 April 1994
 Bibcode:
 1994JAnSc..42..143A
 Keywords:

 Aircraft Approach Spacing;
 Computer Programs;
 Formalism;
 Mathematical Models;
 Orbit Perturbation;
 Orbital Maneuvers;
 Satellite Orbits;
 Satellite Perturbation;
 Satellites;
 Tracking (Position);
 Acceleration;
 Algorithms;
 Anomalies;
 Distance Measuring Equipment;
 Long Term Effects;
 Polynomials;
 Vectors (Mathematics);
 Velocity;
 Astronautics (General)