Solar activity threshold quickens the fall of decades-old space junk

A Vikram Sarabhai Space Centre team tracked 17 long-lived pieces of 1960s space debris for 36 years and found that once solar activity passes roughly two-thirds of a cycle's peak (as measured by sunspot number or the 10.7 cm radio flux), the upper atmosphere drags debris downward more rapidly, accelerating decay across three solar cycles. The finding helps forecast debris reentries and plan safer operations, though the sample is small and polar/high-inclination debris show deviations.