The concept: a system of radar-equipped blimps, each weighing 7,000 pounds, to warn of attacks from low-flying weapons. The cost: $2.7 billion. The outcome: After 17 years, a "zombie" program that is ineffectual and seemingly impossible to kill. A Times investigation reveals the troubles with an expensive Pentagon project and shows how it manages to live on.
http://graphics.latimes.com/missile-defense-jlens/