Washington (Reuters) - The U.S. government has misplaced the original recording of the first moon landing, including astronaut Neil Armstrong's famous "one small step for man, one giant leap for mankind," a NASA spokesman said. Armstrong's famous space walk, seen by millions of viewers on July 20, 1969, is among transmissions that NASA has failed to turn up in a year of searching, spokesman Grey Hautaloma said. "We haven't seen them for quite a while. We've been looking for over a year and they haven't turned up," Hautaloma said. The tapes also contain data about the health of the astronauts and the condition of the spacecraft. In all, some 700 boxes of transmissions from the Apollo lunar missions are missing, he said. "I wouldn't say we're worried -- we've got all the data. Everything on the tapes we have in one form or another," Hautaloma said. NASA has retained copies of the television broadcasts and offers several clips on its Web site. But those images are of lower quality than the originals stored on the missing magnetic tapes. Because NASA's equipment was not compatible with TV technology of the day, the original transmissions had to be displayed on a monitor and re-shot by a TV camera for broadcast. Hautaloma said it is possible the tapes will be unplayable even if they are found, because they have degraded significantly over the years -- a problem common to magnetic tape and other types of recordable media. The material was held by the National Archives but returned to NASA sometime in the late 1970s, he said. "We're looking for paperwork to see where they last were," he said.