Shortly after the Kenneth Arnold sighting of so-called "flying saucers" over Mt. Ranier, and the Roswell crash in 1947, a series of sightings of "green fireballs" began, mostly in the southwestern United States, and almost exclusively over the state of New Mexico.
Often, these types of reports would go without being investigated by any governmental agency, but these sightings took on an ominous flavor. They were very often occurring over sensitive government installations, most notably the Los Alamos and Sandia National Laboratory. The green fireballs were honing in on government secrets.
An investigation was initiated by meteor expert Lincoln La Paz. He concluded that the fireballs were structured, that is, not atmospheric phenomena. Initially at least, they were thought to be of Russian origin. Were the fireballs Cold War spying devices?
So much did the high ranking United States officials fear the agenda of the green fireballs, that several top-secret meetings were held, some at Los Alamos, and others in Washington, D.C. The Air Force Scientific Advisory Board was in charge of the D.C. meetings.
Finally, in December of 1949, Project Twinkle was created. This was to be a network of stations with one duty-observe, study, and collect data on the fireball phenomena. This project did little to solve the mystery, and was disbanded two years later. They had now decided that the phenomena was after all, atmospheric in nature.
There were sightings recorded, but these fell into the "normal" explanation pool. Some of these were birds, airplanes, balloons, rockets, and more. After about one year of study, absolutely no explanation was given for the green fireball mystery. Project Twinkle was a short lived study group.