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For Release: April 12, 1996
DISCOVERIES/TANTALIZING POSSIBILITIES MARK SPACE-BASED LIGHTNING DETECTORS FIRST YEAR OF OPERATION
During its first year in orbit, a NASA lightning detection instrument, the Optical Transient Detector, has made numerous significant contributions to researchers understanding of lightning and severe storms.
The instruments accomplishments were reviewed by scientists at the Global Hydrology and Climate Center in Huntsville, Ala., today, during observations marking the anniversary of the detectors first year of operation.
Launched on April 3, 1995, the orbiting detector produced the worlds first high quality images of lightning on a global scale.
"Using the instrument we have determined that, in some cases, there are up to 20 times more lightning flashes within clouds than observed by the ground-based network," said principal investigator Dr. Hugh Christian of the Global Hydrology and Climate Center. "This is significant because lightning flash rates offer the tantalizing possibility of assisting prediction of tornado formation," according to Christian. With its high detection efficiency and accuracy the instrument is the worlds first space-based lightning sensor that can detect and locate most lightning flashes within its field of view.
Data from instrument shows that severe thunderstorms tend to produce lightning within clouds while the storms are building and then more of a mixture of cloud and ground lightning as the storms dissipate.. The quantity of cloud-to-ground lightning strikes, which can be detected by the present ground-based network, increase only after the storm has matured. "This case study indicates that space-based observations may provide a more advanced warning of severe weather", said Christian. The instrument also observed that more lightning is produced during the northern hemisphere summer than during the southern hemisphere summer.
The Optical Transient Detector is a pathfinder for a follow-on lightning detector called the Lightning Imaging Sensor, scheduled for launch in 1997 on the Japanese Tropical Rain Measuring Mission satellite.
"Looking to the future, this instrument is showing us that lightning observations from geostationary orbit could be very valuable for severe weather prediction and warnings," said Christian.
"The highly compact lightning detector represents a sophisticated new research tool in space," explained project manager Roger Chassay of Marshall Space Flight Centers Science and Applications Projects Office, the organization responsible for developing the instrument and managing its mission.
"The Marshall team placed the lightning detector design and development on a fast track when given the opportunity to fly the instrument on an Orbital Sciences Corp. satellite, Microlab-1. The detector was built tested and delivered in less than a year. Our experience clearly shows for payloads involving small-to-medium size and complexity, we can definitely streamline the development process and provide flight hardware of high quality that produces valuable new science."
The Optical Transient Detector is a highly compact combination of optical and electronic elements. The optics and the electronics are a little bigger than a two-pound coffee can and a typewriter, respectively. In spite of its small size the detector is a major advance over previous technology, detecting lightning under bright, daytime conditions as well as at night.
Data from the lightning detector is analyzed by scientists at the Global Hydrology and Climate Center. The center is operated under cooperative agreement of NASA, the University of Alabama in Huntsville, Ala. and the Universities Space Research Association.
The Optical Transient Detector was carried into orbit by an Orbital Sciences Pegasus rocket.