The recently imagined CRASH Clock indicates that satellites in earth orbit could promptly commence to collide under a crisis situation, such as an intense solar tempest.(Image credit: yucelyilmaz via Getty Images)ShareShare by:
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Satellites that orbit Earth may start to crash into each other in fewer than seventy-two hours under the most adverse circumstances — possibly starting a chain reaction that might render low Earth orbit (LEO) unusable, a recent preliminary study suggests. This duration is shorter by 125 days compared to an equivalent emergency happening only seven years earlier, according to the researchers’ novel “CRASH Clock.”
The quantity of spacecraft circling our world is rapidly escalating, largely owing to the expansion of satellite “megaconstellations,” such as the Starlink network by SpaceX. As of May in 2025, there were no less than 11,700 functional satellites in Earth’s vicinity, the majority situated in LEO — the atmospheric segment up to 1,200 miles (2,000 km) from the Earth’s surface. By comparison, that signifies a 485% growth from approximately 2,000 satellites within LEO toward the end of 2018, prior to the initial Starlink deployment in 2019. And everything points toward this development only gaining momentum.
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In a recent paper, shared on the preprint server arXiv on Dec. 10, researchers suggested a fresh method for assessing the likelihood of a collision if all spacecraft were rendered non-operational by one of these worst-case events. The team named this indicator the Collision Realization And Significant Harm (CRASH) Clock. By imitating the placement of spacecraft within LEO, the CRASH Clock reveals the period before the initial collision materializes. (This mirrors how the well-known “Doomsday Clock” illustrates our separation from a speculative global armageddon.)
“The CRASH Clock serves as a statistical measure for the predicted period before a nearby approach that could precipitate an accident,” Aaron Boley, study co-author and astronomer at The University of British Columbia, conveyed to Live Science in an email. “The premise involves its application as an ecological benchmark to aid in appraising the overall well-being of the orbital zone, while also allowing individuals to appreciate the extent of leeway that exists.”
The quantity of satellites in Earth’s orbit has more than increased fourfold in the past seven years, significantly elevating collision probabilities if these spacecraft were to abruptly relinquish their evasion abilities.
In the current report, the team estimated that the value for the CRASH Clock toward the conclusion of 2025 was approximately 2.8 days, accompanied by a 30% prospect that an accident could transpire within 24 hours of an event that deactivates satellites. This is substantially lower than the clock’s anticipated measurement for 2018, projected at 128 days, which would have granted administrators significantly more duration to reinstate their systems.
These outcomes remain to be scrutinized by other experts, and the study group now infers they mildly understated how abbreviated the CRASH Clock actually extends, Boley communicated to Live Science. Nonetheless, the velocity at which these durations have transformed, regardless of their precise values, presents the greatest source of apprehension. (A more dependable value for the CRASH Clock may be issued later in the year.)
“Observing that variance [in values] constitutes one aspect that prompted us to refine the CRASH Clock further,” Boley stated. He appended that the degree to which the assessment has already diminished holds equal weight as an “indicator for orbital strain” when compared to the CRASH Clock itself.
The CRASH Clock assessment is anticipated to decline further in upcoming years as a greater number of satellites become operational. For example, orbital deployments during 2025 tallied 324, which constitutes a novel milestone and indicates a 25% surge as opposed to 2024, SpaceNews recently revealed.
The researchers have refrained from forecasting explicitly how much the CRASH Clock will fluctuate in subsequent years. Regardless, they posit that the existing trajectory will endure: “Whether the CRASH Clock diminishes will hinge on the sustained drive to develop Earth orbits industrially,” Boley remarked. “Should orbital shells continue to intensify, it might continue to contract.”
The volume of rocket dispatches into orbit attained a novel record during 2025, incorporating this SpaceX Falcon 9 deployment on Jan. 5 last year, which dispatched a European communications satellite into LEO.
The likeliest manner for a CRASH Clock occurrence to play out entails a noteworthy solar occurrence, which is able to momentarily upset satellite mechanisms with sizable radiation dosages, Sarah Thiele, the lead researcher on the study and an astrophysics investigator at Princeton University, informed Space.com, a kindred website of Live Science, recently. Amid such an instance, “it becomes unfeasible to forecast where components are destined to be moving forward,” she continued.
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Should satellites cease operation for longer than the CRASH Clock suggests then numerous impacts might materialize, potentially driving us perilously close to the point of the Kessler Syndrome — a speculative scenario wherein escalating collisions within LEO give rise to space debris expanding exponentially to the degree that unimpeded operation becomes unattainable.
The researchers are hesitant to anticipate the timeframe involved because excessive ambiguity surrounds ensuing satellite collisions, and there is no definitive determination of at which juncture the Kessler syndrome initiates, Boley commented. Nevertheless, he cautioned that negligence may soon result in “early-stage exposure” to an irreversible series of collisions.
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Harry BakerSocial Links NavigationSenior Staff Writer
Harry is a senior staff author based in the U.K. with Live Science. He was a marine biology student at the University of Exeter before undertaking journalist training. His coverage touches extensively on aspects like space discovery, planetary science, space weather, climate dynamics, zoological conduct, and paleontological findings. His most recent piece regarding the solar maximum received “best space submission” recognition at the 2024 Aerospace Media Awards and received a “top scoop” shortlist acknowledgement at the NCTJ Awards for Excellence of 2023. He also authors Live Science’s weekly Earth from space compilation.
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