Most planned satellite mega-constellations would push low Earth orbit past the point of no return, according to a new academic model that updates the classic Kessler syndrome math.
Hugh Lewis of the University of Birmingham posted a preprint on arXiv that reworks the old frameworks to reflect how modern constellations actually behave. The model accounts for active collision avoidance, continuous satellite replenishment and drag profiles tied to each spacecraft’s geometry.
Lewis analyzed 14 planned or partially operational constellations, plus two more under extra assumptions, and sorted them into three buckets: sustainable, unstable and runaway. More than half sit above the unstable or runaway thresholds. In the runaway group, fragment growth never stops, which essentially guarantees a debris cascade.
The worst offenders include SpaceX’s Starmind, a plan to place one million AI data centers in orbit, Blue Origin’s Project Sunrise and China’s Guowang constellation of roughly 13,000 satellites. All three sit above the runaway line. Better performers include Starlink’s mobile satellite service, around 15,000 spacecraft, and Blue Origin’s TeraWave, which benefit from lower orbits where atmospheric drag clears debris faster. Eutelsat’s 528-satellite Next fleet exceeds the unstable threshold simply because it operates at higher altitude.
Lewis also notes the assessments treat each constellation in isolation. Combined with everyone else’s traffic, the crowding looks worse still.
