Space safety is a collaborative effort. No matter how diligently one satellite operator works to ensure safe practices, the actions of others can still pose a threat. Recognizing this shared responsibility, NASA’s Conjunction Assessment Risk Analysis (CARA) team is committed to fostering responsible space operations. A key part of this commitment is making crucial conjunction risk assessment algorithms publicly available as CARA tools.
NASA CARA Tool Banner: Open-source software tools for spacecraft conjunction risk assessment, enhancing space safety and responsible satellite operations.
To empower the global space community, NASA CARA has developed Software Development Kits (SDKs) for its core algorithms and made them accessible on the NASA CARA GitHub repository (https://github.com/nasa/CARA_Analysis_Tools). These CARA tool SDKs are designed to be building blocks, not complete, ready-to-use applications. They provide space operators with the essential components to integrate these algorithms into their own conjunction analysis tool suites.
Each CARA tool SDK includes:
- MATLAB source code for the primary algorithm and necessary supporting routines.
- A simple driver to run the algorithm.
- Test cases and expected results for users to verify correct implementation and operation.
- Comprehensive documentation, often in the form of conference papers, journal articles, and sometimes user guides.
The following CARA algorithms are offered as SDK suites, providing a range of capabilities for conjunction risk assessment:
| CARA Analysis Tools Suite |
|---|
| Two-Dimensional Probability of Collision: This CARA tool implements the classic analytic method for calculating the probability of collision between two objects in space. It includes both the traditional Foster method and the faster Elrod method, offering flexibility in computational approach. |
| Three-Dimensional Probability of Collision: Representing a significant advancement in the field, this CARA tool provides the most accurate analytic probability of collision calculation methodology currently available. It is considered an industry innovation, and the SDK includes the foundational journal article detailing the mathematical principles behind this technique. |
| Monte Carlo Probability of Collision (from TCA): This CARA tool utilizes a Monte Carlo technique to estimate collision probability based on the states and covariances of two objects propagated to the Time of Closest Approach (TCA). While historically valuable, this approach has been largely superseded in accuracy and efficiency by the three-dimensional analytic probability of collision algorithm. |
| Collision Consequence: This CARA tool estimates the potential consequences of a collision by predicting the number of debris fragments (larger than a specified size) that could result from a conjunction. The SDK includes conference papers providing in-depth technical details of the algorithms used for this assessment, crucial for understanding the potential impact of space debris. |
| Single Covariance Maximum Probability of Collision: Specifically designed for scenarios where only one of the two objects involved has a reported covariance, this CARA tool estimates the maximum possible probability of collision. The SDK includes a conference paper explaining the technical details of the algorithm, valuable for situations with limited data. |
| Covariance Realism Assessment: This suite of CARA tools provides algorithms to evaluate the realism of covariance matrices. It assesses their accuracy in describing the actual distribution of residual sets of predicted satellite position errors. The tools also generate graphical displays of results, aiding in the interpretation of covariance data. The SDK includes a conference paper and a technical memorandum detailing the algorithms and offering usage guidance. |
All users, including those outside of NASA, can access and download these CARA tools for their use. These open-source tools are readily available on the NASA Software website (software.nasa.gov) by searching for “CARA,” furthering NASA’s commitment to global space safety and responsible space operations through accessible CARA tool resources.
