Performing Proper Conjunction Assessments

Conjunction Analysis in Orbit: Calculating Accurate Probabilities
 

Introduction: If you improperly use the conjunction assessment tools in STK, you could have a conjunction risk different than your actual risk. It is important to reduce the risk of conjunctions but also reduce the risk of improper usage of these conjunction assessment tools. The accurate and realistic covariance plays an important role in calculating the precise probability of collision. Additionally, reliable force models help reduce the risk of collisions by improving prediction accuracy. 
 

The Importance of Covariance Information: When it comes to assessing the probability of collision between two objects in orbit, covariance information plays a vital role. Without covariance data, the likelihood of collision cannot be accurately determined. Additionally, OD systems that rely on Least Squares method often yield unrealistically low covariance sizes, resulting in artificially lower probabilities of collisions. To obtain a realistic covariance and a reliable probability of collision, the utilization of advanced algorithms like ODTK (Orbit Determination Tool Kit) becomes imperative.
 

Reducing Collision Risk through Orbit Accuracy Improvement: To mitigate the risk of collisions, it is crucial to enhance orbit accuracy during the prediction phase. This can be achieved by gaining a better understanding of force models that influence satellite motion. UMA: Flight Dynamics in conjunction with ODTK facilitates force model calibration and overlap tests. These tests compare the predicted orbit from the previous day with the determined orbit of the current day. In the event of a prediction deviation, force models can be recalibrated to ensure improved orbit accuracy and reduce collision risks.
 

Dealing with Lack of Position + Covariance Information: In scenarios where position data with covariance information is unavailable, there are two options to consider. The first option is to subscribe to a Space Situational Awareness (SSA) service such as COMSPOC, which provides high-accuracy ephemeris data along with realistic covariance. This ensures that accurate conjunction assessments can be performed. The second option, although not recommended, involves using Two-Line Element Sets (TLE) which provide less precise information. In such cases, the Maximum Probability of Collision can be used as a measure to understand the upper limit of probability for different sizes of uncertainties.
 

Conclusion: Conjunction analysis plays a pivotal role in maintaining the safety and operational continuity of satellites in orbit. Accurate assessment of the probability of collision is essential for informed decision-making. By utilizing advanced algorithms, such as ODTK, and obtaining realistic covariance information, space operators can obtain reliable collision probabilities. Additionally, improving orbit accuracy through force model calibration and overlap tests significantly reduces the risk of collisions. By prioritizing accurate conjunction analysis, we can ensure the continued exploration and utilization of space with enhanced safety and efficiency.

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LSAS Tec-Support Team