Background
Lightning has been observed from
space since the early 1960s using both optical and radio frequency sensors.
More than a dozen satellites have flown instruments that have recorded signals
from lightning. The detection of lightning from some of these satellites
was an unanticipated bonus, while for others it was a primary research objective.
Lightning observations have been made by cosmonauts and astronauts dating
back to 1963. Astronauts have occasionally reported discharges having horizontal
extents of many hundreds of kilometers and simultaneous lightning events
occurring between widely separated storms.
Early Space Shuttle Lightning
Experiments
 The
Space Shuttle has been used as a platform for lightning studies from
the beginning of the shuttle program, ever since the Night time and
daytime Optical Survey of Lightning (NOSL) experiment was flown onboard
shuttle missions STS-2, STS-4, and STS-6. This experiment, in turn,
developed from cooperative airborne research efforts between NASA's
Marshall Space Flight Center, the State University of New York at Albany,
and the New Mexico Institute of Mining and Technology at Socorro. The
purpose of these experiments was to learn more about atmospheric electricity
and its relationship to severe storms and their development. They were
conducted using NASA Ames U-2 high altitude aircraft equipped with special
instrument pallets in the bottom of the aircraft to gather both optical
and electrical signatures from the lightning. A CCD TV line scan camera
with a diffraction grating filter also provided crude spectral information.
In the late 1980s (after the
Challenger accident of 1986), a new shuttle lightning program began. The
purpose of this experiment, called the Mesoscale Lightning Experiment, was
to observe lightning directly under the shuttle as it would be seen by unmanned
orbiting satellites. The data obtained from these shuttle flights directly
provided design criteria data for modern and future spaced based sensors
(such as OTD, LIS, and LMS).
Observations of Lightning in
the Stratosphere
 An
examination and analysis of video images of lightning, captured by the
payload bay TV cameras of the space shuttle, provided a variety of examples
of lightning in the stratosphere above thunderstorms. These images were
obtained on several recent shuttle flights while conducting the mesoscale
lightning experiment (MLE). The images of stratospheric lightning illustrate
the variety of filamentary and broad vertical discharges in the stratosphere
that may accompany a lightning flash. A typical event is imaged as a
single or multiple filament extending 30 to 40 km above a thunderstorm
that is illuminated by a series of lightning strokes. Examples are found
in temperate and tropical areas, over the oceans and the land. Shuttle
images and animations can be found in
Space Shuttle Observations of Lightning - Mesoscale Lightning Experiment.
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of Lightning in the stratosphere,
Boeck, W. L., O. H. Vaughan, R. Blakeslee, B. Vonnegut, M. Brook,
and J. McKune, Journal of Geophysical Research, 100, 1465-1475,
1995. Abstract,
Paper
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The Role of the Space Shuttle
Videotapes in the Discovery of Sprites, Jets and ELVES
The sequence of video tape observations
of the upper atmospheric optical flashes called sprites, jets, starters, and
ELVES are described in the successive phases of search, discovery, confirmation,
and exploration for the years before 1993. Although there were credible eyewitness
accounts from ground observers and pilots, these reports did not inspire a
systematic search for hard evidence of such phenomena. The science community
would instead wait for serendipitous observations to move the leading edge
of this science forward. The phenomenon, now known as a sprite, was first
accidentally documented on ground based videotape recordings on the night
of July 6, 1989. Video observations from the space shuttle acquired from 1989
through 1991 provided 17 additional examples to confirm the existence of the
sprites phenomenon. Successful video observations from a mountain ridge by
Lyons, starting July 7, 1993, and night time aircraft video observations by
Sentman and Wescott on July 8, 1993, established the basic science of the
sprite phenomena by acquiring and analyzing data based on hundreds of new
events. The 1994 Sprites campaign and the video titled "Red Sprites and Blue
Jets" popularized the name sprite and provided a vocabulary of terms to describe
the visual attributes. Prior to this video, investigators used a variety of
vague descriptive words to describe the individual events. Also, during the
1994 campaign, Wescott and coworkers obtained the first quantitative measurements
of jets and provided the name "blue jets". A third phenomenon was discovered
in a video from the STS-41 mission (October 1990) in the lower ionosphere
directly above an active thunderstorm. It consisted of a large horizontal
brightening several hundred kilometers across at the altitude of the airglow
layer. In 1995, Lyons and associates confirmed the existence of this type
of very brief brightening which they named Emissions of Light and Very Low
Frequency Perturbations From Electromagnetic Pulse Sources (ELVES). Because
sprites, jets, and ELVES have appeared for millennia, their discovery was
inevitable.
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Role of the Space Shuttle Videotapes in the Discovery of Sprites,
Jets and ELVES,
Boeck, W. L., O. H. Vaughan,Jr., R. Blakeslee, B. Vonnegut, and
M. Brook, Submitted to the Journal of Atmosphere Trrestrial Physics,
1997. Abstract,
Paper
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