Data Acquisition System Monitors Lightning Strikes
- Tuesday, 25 October 2011
Genesis HighSpeed data acquisition system
and Perception software
NASA Kennedy Space Center, based in Cape Canaveral, FL, has one of the highest rates of ground lightning strikes per square kilometer in the United States. In 2009, it was estimated that the NASA Space Shuttle Endeavour launch pad area was struck a minimum of 11 times on the lightning mast and water tower, leading to costly launch delays. A spacecraft is vulnerable to lightning strike damage from the moment it emerges from the Vehicle Assembly Building (VAB) until final launch. During this time, it is important to continuously monitor numerous points to identify any potential induced area lightning effects.
To ensure the safety and effectiveness of planned spacecraft
and future-generation rocket launches, NASA built its own
proprietary lightning monitoring system. Using a series of
high-precision transient recorders and digitizer transmitters,
the system could work alongside a secondary lightning protection
system, with both components remaining effective at each
critical spacecraft launch point. Design of the NASA Kennedy
Space Center lightning protection tool incorporated the use
of tall towers, which support metal cables that could intercept
lightning strikes and divert the current away from the spacecraft
launch vehicle. Two launch pads were protected in the testing area. Launch Pad 39A, used during
active manned shuttle launches,
incorporated one lightning protective
device on top of the pad, while Launch
Pad 39B, designed for next-generation
launches, features three 180-meter-high
lightning protection towers.
The humid Florida climate required the system to have high corrosion and moisture resistance, as well as suitable protection from other environmental contaminants. In addition, the risk of damages caused by the high shock and vibration levels and ambient temperatures typically present during launch required a technology that met specific MIL-SPEC standards. Transmitter input had to be solely DC-powered with an effective switch to battery operation and complete system isolation. Equally important was the ability to switch to a DC charging circuit via remote control after a thunderstorm.
Working with NASA, HBM incorporated the use of the Genesis HighSpeed data acquisition system with Perception software to facilitate review, control, and analysis of captured induced current and voltage data at various points. The system was housed in a corrosion-resistant 304 stainless steel package for high resistance to humidity, moisture, and environmental contaminants. The use of fiber-optic cable effectively supported a distance of up to 12 kilometers be tween numerous measuring points, and IRIG time codes achieved synchronization between multiple mainframes. Fiber-optic transmitters were linked to a receiver that accepted up to four units for single-mode, fiberoptic transmission with 900 MS transient memory. Each measurement point included a remotely controlled test signal source for signal path verification, as well as the capability to analyze and generate automated reports for each lightning event. Effective multipoint monitoring allowed for the identification of locations where high-induced currents may have occurred due to lightning-induced rapid transients.
As a result of successful technology integration, NASA was able to outfit Kennedy Space Center with a highly effective lightning strike monitoring and protection system that reduced launch delays and quickly identified any potentially negative local effects from induced area lightning.