An Orbital House of Cards: Frequent Megaconstellation Close Conjunctions

TL;DR

This paper introduces the CRASH Clock, a new metric to quantify the risk of catastrophic satellite collisions in orbit, revealing a significant increase in orbital environment stress due to megaconstellations, with only days to respond.

Contribution

It proposes the CRASH Clock metric to assess orbital collision risk and highlights the urgent need for improved situational awareness in the era of megaconstellations.

Findings

CRASH Clock is currently 5.5 days, indicating high collision risk.

Pre-megaconstellation CRASH Clock was 164 days, showing increased danger.

Highlights limited time to prevent catastrophic orbital events.

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. While satellites provide many benefits to society, their use comes with challenges, including the growth of space debris, collisions, 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 manoeuvres or there is a severe loss in situational awareness. Our calculations show the CRASH Clock is currently 5.5 days, 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.