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NASA Conjunction Assessment Risk Analysis Updated Requirements

March 28, 2022

What are NASA’s Conjunction Assessment Risk Analysis Updated Requirements?

The NASA Conjunction Assessment Risk Analysis (CARA) program has been performing routine on-orbit satellite conjunction risk analysis for unmanned NASA spacecraft since 2005 and has developed a robust operations procedure and set of recommended best practices for operational conjunction assessment. However, a number of recent developments in Space Situational Awareness and commercial space operations conduct, such as the imminent deployment of much more sensitive space sensing systems and the launching of much larger satellite constellations, have begun to challenge these standard collision risk parameters and calculations. In response, CARA has pursued a multi-year evaluation initiative to re-examine risk assessment algorithms and techniques, to develop needed improvements, and to assemble analysis-based operational requirements. This paper gives an overview of the principal parts of the Conjunction Assessment (CA) risk assessment process used at CARA, outlines the technical challenges that each part presents, surveys the possible solutions, and then indicates which particular solution is being recommended for NASA.

 

Introduction

The NASA Conjunction Assessment Risk Analysis (CARA) program was initiated in January of 2005 to protect the Agency’s unmanned missions from collision with on-orbit objects. The NASA Human Spaceflight (HSF) program, historically supporting missions such as the Space Shuttle, the International Space Station (ISS), and ISS visiting vehicles, had worked with the Department of Defense in the 1980s to develop the high accuracy space object catalog and CA screening products that would eventually develop into the Conjunction Data Message (CDM) and other standard formats in use today. In 2004, CARA was created and, using the basis of the HSF CA process and modifying it to apply to a wider range of orbit regimes and types of vehicles, developed a process that is now required for all non-HSF operational Agency assets. CARA currently supports about 70 spacecraft using the institutional risk assessment process described herein.

However, a number of recent developments in Space Situational Awareness (SSA) and commercial space operations conduct have begun to challenge these standard collision risk parameters and calculations. These developments include the imminent deployment to operations of the Space Fence Radar, an Air Force sensor that is expected to change the sensitivity of the Space Surveillance Network (SSN) from the current detection capability of 10 cm in LEO to 5 cm, as well as the launch of many large constellations (100s to 1000s of members each) to various low Earth altitudes. Both of these developments will increase the workload of analyzing and mitigating close approach events, making improvements to the existing process necessary. Improvements such as decreasing the uncertainty in the relevant computations and the inclusion of more automated processes are necessary to adapt CARA to handle the evolving space environment. Therefore, CARA has pursued a multi-year evaluation initiative to re-examine risk assessment algorithms and techniques, to develop needed improvements, and to assemble analysis-based operational requirements. This paper gives an overview of the CA risk assessment process used at CARA, outlines the technical challenges being encountered, surveys the possible solutions, and then indicates which particular solution is being recommended for NASA. The paper concludes with an inventory of remaining important open research questions as well as statements of the operational utility that would be engendered by their solutions.

To learn more, you can read our white paper “NASA Conjunction Assessment Risk Analysis Updated Requirements Architecture.”

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References
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