BRENDAN I. KOERNER — A new sensor dubbed “Athena” could help prevent friendly-fire deaths, the bane of the U.S. military. An Athena emits synthetic radar echoes, embedded with unique tags that ID a ground vehicle as an ally. When an aircraft pilot scans the Earth for targets to smash, friendly tanks and jeeps are marked “no go” by on-screen icons. Strangely, the Sandia National Laboratories press release doesn’t mention the first problem that popped to my mind: What happens if an enemy swipes an Athena and puts it in his own tank? Hello? Haven’t these Pentagon folks ever seen Return of the Jedi? A stolen shuttle ID code is what got Luke and his cohorts onto Endor. Yes, with an assist from Darth Vader’s willful ignorance, but you get the point.