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SATELLITE COLLISION PREDICTION AND AVOIDANCE SYSTEM

IP.com Disclosure Number: IPCOM000009823D
Original Publication Date: 2000-May-01
Included in the Prior Art Database: 2002-Sep-20
Document File: 8 page(s) / 365K

Publishing Venue

Motorola

Related People

David E. Gaylor: AUTHOR [+3]

Abstract

This paper presents methods for predicting potential collisions between satellites, computing the probability of collision and determining orbital maneuvers to avoid those collisions. These techniques are particularly useful for designing and operating large satellite constellations.

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MOTOROLA

Technical Developments

SATELLITE COLLISION PREDICTION AND AVOIDANCE SYSTEM

by David E. Gaylor, Dr. Robert Gottlieb and Steven J. Sponaugle

INTRODUCTION

This paper presents methods for predicting potential collisions between satellites, computing the probability of collision and determining orbital maneuvers to avoid those collisions. These techniques are particularly useful for designing and operating large satellite constellations.

The first step in the process is predicting potential satellite collisions. Orbit determination is per~ formed for all of the subject satellites using any of several techniques, such as: ground based laser tracking, ground based RF tracking, onboard GPS receivers, etc. Once the orbits for all satellites of interest have been determined, the Analytic Collision Prediction Algorithm is used to determine which pairs of satellites may collide. Traditionally, this has been done by numerically integrating the equations of motion for each object. Then the position of each object would be compared to every other object at each time step over the time span of interest. This can be a very large job when a number of satellites are considered. The Analytic Collision Prediction Algorithm improves the speed and efficiency of collision prediction by employing simple geometric calculations instead of numerical integration of differential equations.

The Analytic Collision Prediction Algorithm can be used to:

1. Evaluate proposed orbital maneuvers for collision risk.

2. Evaluate the distance of closest approach for a given constellation design.

3. Determine locations in a given constellation where a satellite should not be placed.

Motorola, Inc. 2000

The Analytic Collision Prediction Algorithm reduces the computational burden by analytically ruling out pairs of objects that cannot collide without integrating equations of motion. The Analytic Collision Prediction Algorithm is composed of two filters; the first filter is the Apogee-Perigee filter and the second is the Argument of Latitude filter. The Apogee-Perigee filter checks to see if the apogee of one object is below perigee of the other (with some tolerance to account for uncertainty) or vice versa.

If so, this pair of objects will not collide.

The Argument of Latitude filter rapidly determines if collisions are possible between any two satellites of a group of satellites that have nearly the same semi-major axis but are in different planes. If a pair of satellites is predicted to potentially collide, their orbits are precisely computed using numerical integration to determine the actual distance of closest approach.

The probability of collision between the two satellites is computed based on the precise orbits and the uncertainties in the orbital data. If the probability of collision is deemed to be too high, one of the two satellites is comtnanded to perform an orbital maneuver to reduce the probability of colli~ sion.

ANALYTIC COLLISION PREDICTION ALGORITHM

Once the...