asteroid evolution would cause a similar collision process in LEO in decades rather than billions of years. They concluded that by about 2000, space debris would outpace micrometeoroids as the primary ablative risk to orbiting spacecraft. At the time, it was widely thought that drag from the upper atmosphere would de-orbit debris faster than it was created. However, Gabbard was aware that the number and type of objects in space were under-represented in the NORAD data and was familiar with its behavior. In an interview shortly after the publication of the 1978 paper, Gabbard coined the term Kessler syndrome to refer to the accumulation of debris; it became widely used after its appearance in a 1982 Popular Science article, which won the Aviation-Space Writers Association 1982 National Journalism Award. Follow-up studies The lack of hard data about space debris prompted a series of studies to better characterize the LEO environment. In October 1979, NASA provided Kessler with funding for further studies. Several approaches were used by these studies. Optical telescopes and short-wavelength radar were used to measure the number and size of space objects, and these measurements demonstrated that the published population count was at least 50% too low. Before this, it was believed that the NORAD database accounted for the majority of large objects in orbit. Some objects (typically, US military spacecraft) were found to be omitted from the NORAD list, and others were not included because they were considered unimportant. The list could not easily account for objects under in size—in particular, debris from exploding rocket stages and several 1960s anti-satellite tests. Returned spacecraft were microscopically examined for small impacts, and sections of Skylab and the Apollo Command/Service Module which were recovered were found to be pitted. Each study indicated that the debris flux was higher than expected and debris was the primary source of micrometeoroids and orbital debris collisions in space. LEO already demonstrated the Kessler syndrome. In 1978, Kessler found that 42 percent of cataloged debris was the result of 19 events, primarily explosions of spent rocket stages (especially US Delta rockets). He discovered this by first identifying those launches that were described as having a large number of objects associated with a payload, then researching the literature to determine the rockets used in the launch. In 1979, this finding resulted in establishment of the NASA Orbital Debris Program after a briefing to NASA senior management,