Kosmos 2421 (Cosmos 2421) was a Russian reconnaissance satellite launched in 2006, but began fragmenting in early 2008.[1] It also had the Konus-A science payload designed by Ioffe Institute to detect gamma-ray bursts.[2] Three separate fragmentation events produced about 500 pieces of trackable debris.[1] About half of those had already re-entered Earth's atmosphere by the fall of 2008.[3]