An orbital house of cards: Frequent satellite close conjunctions

2025/12/10 by Sarah Thiele, Thiele, Sarah, Skye R. Heiland +7 · 42 voices
Engineering · Mathematics · #Space Satellite Systems and Control #Mathematics and Applications #Spacecraft Dynamics and Control

paper · pdf · doi:10.1016/j.actaastro.2026.06.023

Abstract

The number of objects in orbit is rapidly increasing, primarily driven by the launch of megaconstellations, an approach to satellite constellation design that involves large numbers of satellites paired with their rapid launch and disposal, as well as the overall proliferation of satellite systems. While satellites provide many benefits to society, their use comes with challenges, including the growth of space debris, collision risks, ground casualty risks, optical and radio-spectrum pollution, and the alteration of Earth's upper atmosphere through rocket emissions and reentry ablation. There is potential for current or planned actions in orbit to cause serious degradation of the orbital environment or lead to catastrophic outcomes, highlighting the urgent need to find better ways to quantify stress on the orbital environment. Here we propose a new metric, the CRASH Clock, that measures such stress in terms of the timescale for a possible catastrophic collision to occur if there are no satellite maneuvers or there is a severe loss in situational awareness. Our calculations show that the CRASH Clock is 5.5 days as of June 2025 and continues to decrease, which suggests there is limited time to recover from a wide-spread disruptive event, such as a solar storm. This is in stark contrast to the pre-megaconstellation era: in 2018, the CRASH Clock was 164 days.

Citations

• Greenhouse gases reduce the satellite carrying capacity of low Earth orbit
• Satellite Drag Analysis During the May 2024 Gannon Geomagnetic Storm

Discussions

• An Orbital House of Cards: Frequent Megaconstellation Close Conjunctions [hn, 90 points, 46 comments]
• Oh, look. Yet another thing that Elmo is ruining for everyone. And other megaconstellation producers. Welp, the super rich are screwing up their own space access. youtu.be/b66ZZ05wKC0?... arxiv.org/pd [bsky, 19 points, 2 comments]
• "Megaconstellations May Be Just 2 Days Away From Causing a Kessler Syndrome" by Anton Petrov [lemmy, 11 points, 2 comments]
• Do you know how crowded it is up in space? If we lost connections to a large number of satellites on orbit, due to e.g. a circuit-frying solar flare, a cascade of collisions could result in days, crea [bsky, 11 points, 1 comments]
• Paper here: arxiv.org/abs/2512.09643 tl;dr If there's an event that makes collision avoidance maneuvers temporarily not possible (e.g. major solar storm, SpaceX shutting down or maybe a software hack [bsky, 6 points, 0 comments]
• 🤯 Very interesting study featured on spaceweather.com today about #solarstorms lowering satellite orbits and thus collision avoidance maneuvers are needed, in particular for satellite megaconstellati [bsky, 5 points, 0 comments]
• Source link, Princeton study; arxiv.org/pdf/2512.09643 [bsky, 4 points, 1 comments]
• Today on the arXiv: Thiele et al. 2026, "An Orbital House of Cards: Frequent Megaconstellation Close Conjunctions" - arxiv.org/abs/2512.09643 It remains way past time to stop letting corporations unil [bsky, 3 points, 0 comments]
• "if collision avoidance manoeuvres were to suddenly stop [...] within 24 hours there is a 30% chance of a collision between two catalogued RSOs and a 26% chance of a collision involving a Starlink sat [bsky, 2 points, 1 comments]
• you could read the paper he's referring to. I looked at it myself and it seemed convincing but i have to admit im pretty tired right now. arxiv.org/pdf/2512.09643 [bsky, 2 points, 1 comments]
• The window for an unrecoverable collision for uncorrected low earth orbital flight is up 43 fold since 2018. arxiv.org/abs/2512.09643 #amateurradio #hamradio coosradioclub.com/2025/12/21/k... [bsky, 2 points, 0 comments]
• This comes as a recent study out of Princeton cites that the time between a loss of collision avoidance for satellites, and the possibility of an accidental strike is closer than ever before. Such a l [bsky, 2 points, 1 comments]
• If a solar flare knocks out sat coms for just a few days, we could have a collision which could start the Kessler Syndrome and destroy our access to space: 2026 is part II. arxiv.org/pdf/2512.09643 [bsky, 1 points, 0 comments]
• "While satellites provide benefits, their use comes with challenges, including the growth of space debris, collisions, ground casualty risks, optical and radio-spectrum pollution, and the alteration o [bsky, 1 points, 0 comments]
• An Orbital House of Cards: Frequent Megaconstellation Close Conjunctions arxiv.org/pdf/2512.09643 [bsky, 1 points, 0 comments]
• C'est ce qu'indique l'étude oui. Si plus aucun satellite ne peut effectuer de manœuvres d'évitement, alors il y aurait une collision en moins de 3 jours. Contre 141 jours en 2018 😅 arxiv.org/pdf/2512 [bsky, 1 points, 1 comments]
• An Orbital House of Cards: Frequent Megaconstellation Close Conjunctions arxiv.org/abs/2512.09643 [bsky, 1 points, 0 comments]
• I remember when this was a theoretical/far-futurish concern... via spaceweather.com [bsky, 1 points, 0 comments]
• All of these growing constellations aim for thousands of satellites in the future Ten years ago there were only about 1,400 active satellites--TOTAL. The current near-Earth environment is 10 times as [bsky, 1 points, 1 comments]
• Alle ~22 Sekunden treffen sich zwei Satelliten im Low-Earth-Orbit mit unter 1 km Abstand. Das erfordert 100K Kurskorrekturen pro Jahr. 2018 konnten wir noch 121 Tage untätig sein (z.B. wegen Solarstur [bsky, 0 points, 0 comments]
• An Orbital House of Cards: Frequent Megaconstellation Close Conjunctions view on hacker news [bsky, 0 points, 0 comments]
• An Orbital House of Cards: Frequent Megaconstellation Close Conjunctions https:// arxiv.org/abs/2512.09643 # arxiv [mastodon, 0 points, 0 comments]
• An Orbital House of Cards: Frequent Megaconstellation Close Conjunctions https://arxiv.org/abs/2512.09643 (https://news.ycombinator.com/item?id=46232220) [bsky, 0 points, 0 comments]
• @heiseonline eine Studie hat ergeben dass es zum Kessler Syndrom kommt wenn SpaceX nur 3 Tage lang keine Kommandos zu den Satteliten schicken kann. https://arxiv.org/pdf/2512.09643 [bsky, 0 points, 0 comments]
• Publication arxiv.org/abs/2512.09643 [bsky, 0 points, 0 comments]
• "An Orbital House of Cards: Frequent Megaconstellation Close Conjunctions" by Thiele, Heiland, Boley, & Lawler #Starlink #ElonMusk arxiv.org/abs/2512.09643 [bsky, 0 points, 1 comments]
• CRASH CLOCK COUNTDOWN An Orbital House of Cards: Frequent Megaconstellation Close Conjunctions 10 December 2025 arxiv.org/pdf/2512.09643 [bsky, 0 points, 0 comments]
• Arxiv.org/abs/2512.09643 [bsky, 0 points, 0 comments]
• An Orbital House of Cards: Frequent Megaconstellation Close Conjunctions https://arxiv.org/abs/2512.09643 (https://news.ycombinator.com/item?id=46232220) [bsky, 0 points, 0 comments]
• 2.8 days to disaster: Why we are running out of time in low earth orbit arxiv.org/pdf/2512.09643 [bsky, 0 points, 0 comments]
• And then there's the Crash Clock... arxiv.org/abs/2512.09643 [bsky, 0 points, 0 comments]
• The odds of a massive cascade of collisions in low earth orbit appears to be frighteningly higher than previously thought. arxiv.org/abs/2512.09643 [bsky, 0 points, 0 comments]
• [2512.09643] An Orbital House of Cards: Frequent Megaconstellation Close Conjunctions arxiv.org/abs/2512.09643 [bsky, 0 points, 0 comments]
• [2512.09643] An Orbital House of Cards: Frequent Megaconstellation Close Conjunctions arxiv.org/abs/2512.09643 [bsky, 0 points, 0 comments]
• An Orbital House of Cards - Frequent Megaconstellation Close Conjunctions: arxiv.org/abs/2512.09643 -> thread scicomm.xyz/@sundogplane... [bsky, 0 points, 0 comments]
• Glorious ~~~ arxiv.org/abs/2512.09643 #KesslerSyndrome [bsky, 0 points, 1 comments]
• Especially after reading this: arxiv.org/abs/2512.09643 [bsky, 0 points, 0 comments]
• arxiv.org/abs/2512.09643 [bsky, 0 points, 0 comments]
• https://bsky.app/profile/hackernews.com.web.brid.gy/post/3m7pwmsbrxir2 [bsky, 0 points, 0 comments]
• An Orbital House of Cards: Frequent Megaconstellation Close Conjunctions #HackerNews https://arxiv.org/abs/2512.09643 [bsky, 0 points, 0 comments]
• An Orbital House of Cards: Frequent Megaconstellation Close Conjunctions https://arxiv.org/abs/2512.09643 [bsky, 0 points, 0 comments]
• #satellite #collision #debris #pollution #atmosphere #space #CRASHclock Original open access article Thiele et al. 8 Jan 2026, arXiv_astro-ph An Orbital House of Cards: Frequent Mega-constellation [bsky, 0 points, 0 comments]

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