Friday, March 14, 2008

"Endeavoring" to understand the forces of nature...

By Dustin Williams
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With the launch of the space shuttle Endeavour on Tuesday morning, NASA began a 16-day mission to the International Space Station (ISS) to install part of a Japanese laboratory and the Canadian Space Agency's two-armed gargantuan robotic system Special Purpose Dexterous Manipulator (SPDM). From this title they somehow got the nickname "Dextre" instead of "Dexter." Have you seen this thing? It's ridiculous. Each arm is three meters long and has seven joints, which enables it to be flexible and capable of performing tasks on the exterior of the ISS in lieu of a spacewalking astronaut.

I got to thinking about the impacts of weather on launches. Most are obvious, I think. It doesn't take much in the way of cloud cover and rain or even wind in order to scrub a launch. Really, any weather that threatens the aerodynamics and electrical system of the shuttle can result in a scrub, which is why the 650 square miles encompassed by Kennedy Space Center (KSC) and Cape Canaveral Air Force Station are littered with meteorological instruments. The NASA and Air Force 45th Weather Squadron meteorologists have a tough job in the days leading up to a launch. If inclement weather is possible but not certain, they have to weigh the costs of scrubbing and rescheduling the launch, which is not cheap, versus risking life and property. I don't envy them. Oh wait, maybe I do. They get government benefits and live on the beach. Hmmm.

At the University of Oklahoma, I'm doing research for NASA, and have had the opportunity to travel to the Kennedy Space Center and meet with their meteorologists. Perhaps their biggest concern of all weather is with lightning. The research I'm doing is attempting to determine if predicative value can be found in surface electric field data as it relates to cloud-to-ground lightning in a "pulse" thunderstorm. "Pulse" means a thunderstorm that develops in a relatively short period of time, and is hard to detect until it's already producing lightning. These thunderstorms pose the most danger. A squall line over Orlando that's moving east won't sneak up on anyone at KSC; a pulse thunderstorm that produces lightning might.

One of the more interesting things about lightning is that it can be triggered by the shuttle. Even if there are no thunderstorms around, if the electrical properties within a cloud are ripe, the shuttle can actually act as a conduit for the lightning by helping bring charge of the sign opposite to that in the cloud upward. This is obviously a big concern. NASA scientists use various instruments to measure the electrical and moisture properties above the ground to try to foresee when this might happen.

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