Low Earth orbit now holds thousands of satellites, and the count keeps rising. That growth has made space feel roomy in theory, but tight in practice. In a new study, researchers from Princeton University, the University of British Columbia and the University of Regina propose a simple warning metric: the Collision Realization And Significant Harm Clock, or CRASH Clock. Graduate student Sarah Thiele, now at Princeton, helped lead the work after starting it as a Ph.D. student at the University of British Columbia. Her co-authors include physics and astronomy professor Aaron Boley at the University of British Columbia in Vancouver, Canada, and astronomy associate professor Samantha Lawler at the University of Regina in Saskatchewan, Canada. Their paper asks a blunt “what if” question: If satellite operators suddenly could not steer, how long would it take before a major crash becomes likely? Their current answer is 5.5 days. That number comes from a worst-case thought experiment where maneuvering stops across low Earth orbit, whether from a severe solar storm, a software failure, or some other broad …