National Geographic : 2012 Aug
• lm technology with extremely sensitive digital sensors designed for deep-space exploration and adding specially tailored so ware and circuitry. But no matter how you modify it, an instrument weighing close to a ton has obvious drawbacks. In addition to its lack of maneuverability, the as- toundingly fast Kahuna is in another sense very slow. Each time you want to take an ultra-high- speed shot, you have to wait about ten seconds for the turbine to spin up to speed. en you have about a minute before you have to spin it down so it doesn't overheat. If you've been lucky enough to capture an image, it will take a full 20 minutes to download the 1.8 gigabytes of data to see what you've got. Only then can you recock the trigger and try again. In other words, Samaras will need a station- ary storm that is producing lightning again and again, right where the camera is pointing. Some people rate his chances of success at close to zero. ere are research facilities where he could reduce at least some of the variables by deploy- ing the Kahuna on lightning triggered by ring rockets into storm clouds. But Samaras is dismis- sive of manufactured lightning---only the wild type will do. He is used to having people tell him that what he's trying can't be done. Before he became ob- sessed with lightning, he spent several years chasing a er tornadoes. He had designed elec- tronic probes, mounted with video cameras and other instruments, to lay down in the likely path of a tornado so he could record what it looks and feels like from the inside. People were dubious about that too, but he managed to gather some of the most accurate readings ever of wind speed, barometric pressure, temperature, humidity---the ingredients that when mixed just so erupt into a devastating funnel of wind. With hopes of catching up to the storm, we pass through Liberal, Kansas, and then head straight north toward Sublette. A dark mass of clouds is building over the plains. As the sun sets, the tops of the clouds cool. at means more upli , more separation between negatively and positively charged particles, and more lightning. By the time we pull to the side of the road, the storm has become so violent that in the distance it has spawned a small tornado. The twister quickly dissipates, leaving a spectacular lightning show. Two long bolts crisscross the sky like an electrified X, followed by a barrage of ground the paths of downward stepped leaders and oc- casionally the upward streamers. But as soon as the two connect---initiating an event called the attachment process---the ash from the return stroke blinds the camera, obliterating the details. Scientists would love to peek behind the curtain and watch the event as it unfolds, with the return stroke li ing o like a rocket from the ground. Lying within the imagery might be clues to some of lightning's biggest mysteries. Why will a lightning bolt sometimes strike a low tree when right beside it is a tall metal tower? And why, for that matter, does lightning strike at all? For all their intensity, the voltages produced in thun- derclouds are not nearly strong enough to over- come the insulating properties of air. Some extra factor is required, and a picture of the attach- ment process might suggest an answer. Opening this frontier calls for a custom-out tted camera capable of shooting more than a million high- resolution frames per second. ere's just one camera like that, and it too is in Samaras's trailer. Weighing 1,600 pounds and standing six feet high, the camera is a relic of the Cold War, origi- nally used to lm aboveground nuclear tests. Samaras rst laid eyes on it in 1980, when he was working as a technician at the University of Denver Research Institute. e massive instru- ment was a marvel of analog technology. Light entering its main lens would strike a three-sided mirror, which sat at the center of a turbine driven by compressed air or, for really high speeds, he- lium. Rotating as fast as 6,000 revolutions per second, the mirror swept the light across the lenses of 82 35-millimeter lm cameras, mounted shoulder to shoulder around the rim. e result was a sequence of images less than one-millionth of a second apart. Samaras's job involved studying convention- al explosions, and he became the behemoth's keeper, learning its idiosyncrasies, catering to its whims. Twenty- ve years later, when he heard that the camera was being auctioned as government surplus, he placed a bid and bought it for $600---a hair above the price for aluminum scrap. Its proper name is a Beckman & Whitley 192. Samaras calls it the Kahuna. With the help of funding from National Geo- graphic, he retro tted the beast, replacing the n Society Grant Tim Samaras's lightning and tornado research is funded in part by your Society membership.