If you thought laser weapons were science fiction, think again. At www.trw.com/thel, there's the first evidence that they are becoming a reality: watch the US Tactical High Energy Laser detonate the warhead of a Katyusha rocket in flight. The rocket nose glows briefly and then explodes—viewed in three short clips taken from different cameras. The US Army and the Israeli Ministry of Defense paid weapons contractor TRW $200 million to build the chemical laser, in which atomic fluorine reacts with the heavy hydrogen isotope deuterium to generate a powerful infrared beam that can pass through the atmosphere.

Israel wants lasers to blast Hezbollah missiles apart, since, as the US Army says at www.smdc.army. mil/FactSheets/THEL.html, firing artillery shells at rocket launchers "may not be an option in densely populated areas". But the system itself is quite a target, amounting to several truckloads of hardware (www.trw. com/seg/sats/THEL.html). What the army really wants ...