Astronomical Data Analysis Software & Systems XXXIV

NEOCC’s Aegis pipeline in asteroid orbit determination and impact monitoring.
2024-11-14 , Aula Magna

The Near-Earth Objects Coordination Centre (NEOCC) is the main component of the Planetary Defence Office (PDO) within ESA's Space Safety Programme (S2P). Its mission is to support and coordinate the observations of small Solar System bodies and assess and track the threats they may pose to Earth. Central to this mission is Aegis (1), an automated orbit determination and impact monitoring system developed by SpaceDyS s.r.l. under ESA contract and operated by NEOCC. Aegis plays a critical role in the daily operations of the NEOCC, providing up-to-date information on orbital properties, impact probabilities, and risk analysis for near-Earth objects.

Aegis operates on an hourly basis, continuously downloading new astrometric data from the Minor Planet Center. It is primarily based on two components: orbit determination and impact monitoring. The orbit determination component maintains a dynamic catalogue of near-Earth asteroids, which includes orbital parameters with associated uncertainties, physical properties such as visual and absolute magnitude, observation details, residuals, close approaches, and ephemerides. The impact monitoring component computes the impact probabilities of near-Earth asteroids over the next 100 years. Objects with non-zero impact probabilities are listed in the NEOCC Risk List (2). When an object’s impact probability exceeds a certain threshold, Aegis also computes the associated impact corridor, further refining the risk assessment.

This presentation will focus on the Aegis processing pipeline, which leverages Docker services for the automated download and integration of observational data. Aegis begins by downloading observational data from the Minor Planet Center, after which it employs a dedicated weighting scheme to prioritize observations. This scheme considers the observatory, technology, and program codes associated with each observation. This allows us to apply different rules based on the historical relevance of each observatory. The system’s ability to adjust the significance of data inputs ensures robust and accurate orbit determination.
A crucial output of this pipeline is the “Residual Weights Observations” (rwo) format, an ad-hoc data structure that encapsulates not only the astrometric information, but also detailed data used in the orbit computation, such as weights and observational residuals. This data is accessible through the NEOCC webportal and its APIs (3).
This presentation will also cover the Aegis processing pipeline for the impact monitoring component. This method relies on sampling the Line of Variation, a 1-dimensional differentiable curve in the orbital elements space that identifies the direction with the largest uncertainty. The output of this sampling is then propagated for 100 years from the current epoch, searching for close approaches and potential impacts with Earth. Both sets of information are published in the NEOCC webportal on a daily basis.

By leveraging real-time processing capabilities and advanced data analysis through the rwo format, Aegis provides an essential service in the continuous monitoring of NEOs, contributing to the safety and security of our planet. This presentation will delve into the technical aspects of the Aegis pipeline, emphasizing its real-time functionality and the use of the rwo format and weighting scheme in astronomical data analysis.

(1) https://ui.adsabs.harvard.edu/abs/2023sndd.confE..73F/abstract
(2) https://neo.ssa.esa.int/risk-list
(3) https://neo.ssa.esa.int/computer-access

See also: PowerPoint presentation (8.0 MB)