The role of the space shuttle videotapes in the discovery of sprites, jets and elves

Abstract The sequence of videotape 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 accidently documented on ground based videotape recordings on the night of 6 July, 1989. Video observations from the space shuttle acquired from 1989–1991 provided 17 additional examples to confirm the existence of the sprite phenomenon. Successful video observations from a mountain ridge by Lyons, starting on 7 July, 1993, and night-time aircraft video observations by Sentman and Wescott on 8 July, 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 entitled ‘‘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 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. The partial history related in this paper outlines the unsophisticated activities using space shuttle videotapes and the dissemination of the results by video presentations during the early phases of sprite research. This paper does not attempt to evaluate the advances in the science based on the measurement campaigns of Lyons, Sentman and many other investigators.