Monitoring near-Earth-object discoveries for imminent impactors

TL;DR

NEORANGER is an automated system that calculates impact probabilities for near-Earth objects, issuing alerts for imminent impactors and monitoring for other interesting objects, with proven accuracy on past impact events.

Contribution

The paper introduces NEORANGER, a novel automated impact monitoring system that computes impact probabilities in real-time for objects on the NEOCP, including natural satellites.

Findings

Successfully predicted 2008 TC3 and 2014 AA impacts.

Impact probabilities for typical NEOCP objects are below 1 in 10 million.

Impact probabilities for actual impactors exceed 10% after initial data.

Abstract

We present an automated system called NEORANGER that regularly computes asteroid-Earth impact probabilities for objects on the Minor Planet Center's (MPC) Near-Earth-Object Confirmation Page (NEOCP) and sends out alerts of imminent impactors to registered users. In addition to potential Earth impacting objects NEORANGER also monitors for other types of interesting objects such as Earth's natural temporarily-captured satellites. The system monitors the NEOCP for objects with new data and solves, for each object, the orbital inverse problem which results in a sample of orbits that describes the, typically highly-nonlinear, orbital-element probability-density function (PDF). The PDF is propagated forward in time for 7 days and the impact probability is computed as the weighted fraction of the sample orbits that impact the Earth. The system correctly predicts the then-imminent impacts of 2008 TC3 and 2014 AA based on the first data sets available. Using the same code and configuration we find that the impact probabilities for objects typically on the NEOCP, based on 8 weeks of continuous operations, are always less than 1 in 10 million whereas simulated and real Earth-impacting asteroids always have an impact probability greater than 10% based on the first two tracklets available.