For a vision of war, it was almost elegant. The smoke and stink and deafening crack of munitions would be replaced by invisible beams of focused light. Modified 747 jets, equipped with laser weapons, would blast ballistic missiles while they were still hundreds of miles from striking our soil. “Directed-energy” cannons would intercept incoming rockets at the speed of light, heating up the explosives inside and causing them to burst apart in midair.

And this wasn’t some relic of Reagan-era Star Wars visionaries. These were modern plans, initiated barely a decade ago, that would be realized not in some far-off future, but soon. Out in the New Mexico desert at the White Sands Missile Range, the U.S. Army’s Tactical High Energy Laser shot down dozens of Katyusha rockets and mortars. In 2004, Air Force contractors began test-firing the chemically powered beam weapon for a retrofitted 747, the Airborne Laser.

Then reality set in, and these recent efforts to wield battlefield lasers suddenly began looking as doomed as Star Wars. Generating the megawatts of laser power needed to detonate a missile required hundreds of gallons of toxic chemicals–ethylene, nitrogen trifluoride. The weapons grew bulky. Worse, after a few shots, the lasers would have to be resupplied with a fresh batch of reactants. The logistics of hauling those toxins either through the air or across a battlefield made generals shiver. And questions lingered about how effectively the beams would penetrate dust and rain. Last year, the Army canceled its Tactical High Energy Laser project, and some think the wildly overbudget beam-firing 747 may be next to go.

But don’t count laser weapons out yet. The ray-gun potential of weapons that fire with precision over tremendous distances is far too militarily appealing, particularly at a time when American soldiers are fighting guerrilla foes who melt quickly into the background. “If I could reach into a crowd and take out one or two targets without a puff of dust or a crack of a rifle—if I could fire for a long time, without ever having to reload,” says Marine Corps Major General Bradley Lott, “that’s something the United States Marine Corps would be very, very interested in pursuing.”

Noah Shachtman wrote this piece for Popular Science. You can read the entire story at LiveScience.com