Michael Hoot, SpaceX; Reid Hymes, SpaceX; Alex Petrov, SpaceX; Ian Ruh, SpaceX; Alexander Koenig, SpaceX
https://doi.org/10.64861/XPVB9629
Keywords: Space Traffic Coordination, Conjunction Assessment, Collision Avoidance, Space Domain Awareness, Stargaze, Starlink, Constellation, SpaceX, Low-Latency
Abstract:
Historically, satellite operators have relied on a small number of platforms for Space Situational Awareness (SSA) and conjunction screening services, which run a small number (3-6) of full-catalog screenings per day. Many satellite operators do not publish predicted ephemerides for their satellites at all, and rely solely on those SSA systems to detect upcoming conjunctions. Even for operators that do publish predicted ephemerides, rate limits may prevent them from publishing more than a handful of times per day, and it may take hours for the next screening to produce results. This may give satellite operators the false impression that there is little risk reduction available by publishing or screening ephemerides more frequently.
However, after collecting 30,000 satellite-years of flight data, SpaceX has found that there are a handful of drivers (including the “launch COLA gap”, failed or unannounced maneuvers, geomagnetic storms, and ephemeris quality issues) that contribute disproportionately to collision risk in Low-Earth Orbit (LEO). These are difficult problems to solve comprehensively; however, much of the collision risk they cause can be mitigated by a more responsive paradigm, where ephemerides are published and screened in near-real time.
space-safety.com is a conjunction screening and space traffic coordination platform built by SpaceX to allow very frequent ephemeris sharing and near-real-time conjunction screening. SpaceX runs this platform free of charge and encourages operators to publish predicted ephemerides as frequently as possible, ideally every time new ephemeris data becomes available. Ephemerides from Starlink satellites are updated here hourly, and objects that are tracked well by Stargaze, SpaceX’s SSA system, are updated every 10-15 minutes. Screenings are performed continuously, with results available seconds after submission. The platform processes over 500,000 ephemeris files, producing over 50,000,000 Conjunction Data Messages (CDMs) daily. In addition to producing CDMs, the platform performs on-the-fly calculation of the empirical prediction accuracy of submitted ephemerides, both in terms of absolute error and covariance realism. This allows operators to diagnose and correct errors in their own ephemeris generation, as well as evaluate the historical accuracy of secondary predictions when performing conjunction assessment. The fast turnaround time also gives operators the opportunity to submit “hypothetical” trajectories for iterative maneuver planning and analysis.
This paper will present aggregate data and case studies illustrating some of the biggest drivers of collision risk in LEO, and demonstrate how a more reactive SSA and screening platform has allowed SpaceX to mitigate some of this risk. It will discuss the design decisions made to enable high-throughput, low-latency conjunction screening, and how satellite operators might integrate this platform into their operations.
Date of Conference: September 15-18, 2026
Track: Conjunction/RPO