CRASH Clock (26 January 2026): 3.8 days.
The CRASH Clock is an environmental indicator for assessing the collision risk in low Earth orbit (LEO). Details can be found in this preprint (revised based on community feedback): https://arxiv.org/abs/2512.09643.
The Crash Clock asks, What is the expected time for a potential collision in LEO between tracked artificial objects — including satellites, debris, and abandoned rocket bodies — if all manoeuvres were to stop? While this is a hypothetical situation, it reflects the degree to which humanity is dependent on errorless operations in orbit. The CRASH Clock also does not consider non-trackable objects.
Some reference CRASH Clock values are:
26 January 2026: 3.8 days
25 June 2025: 5.5 days
1 January 2025: 6.8 days
1 January 2024: 6.8 days
1 January 2023: 11 days
1 January 2022: 26 days
1 January 2021: 62 days
1 January 2020: 102 days
1 January 2019: 119 days
1 January 2018: 164 days
Another way to think of the CRASH Clock is the reaction time needed to respond to a serious loss of space situational awareness. As an example, consider the probability of a potential collision within 24 hr (for no manoeuvres) as a function of CRASH Clock value. The “Danger Zone” is given as the CRASH Clock for which there is more than a 50% probability of having a collision, while the green represents CRASH Clock values for which there is less than a 10% probability.
