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The Apollo 11 missing tapes refers to Apollo 11's slow-scan television (SSTV) telecast recorded in its raw format on telemetry data tape during the time of the first Moonlanding in 1969. The recordings were discovered to be "missing" after a team of retired NASA employees and contractors tried to locate the tapes in the early 2000s. The data tapes were recorded as a backup in case the live television broadcasts failed for any reason. In order to broadcast the SSTV transmission on standard television, NASA ground receiving stations performed real-time scan conversion to the NTSC television format. The moonwalk's converted video signal was broadcast live around the world on July 21, 1969 (UTC). At the time, the NTSC broadcast was recorded on many videotapes and kinescope films: they were never missing. The search was sparked when several still photographs appeared in the late 1990s that showed the superior-looking raw SSTV transmission on ground station monitors. The research team conducted a multi-year investigation in the hopes of finding the most pristine and usable versions of the moonwalk. If the original SSTV format tapes were to be found, more modern digital technology could make a higher-quality conversion, yielding better images than those originally seen. The researchers discovered that the tapes containing the raw unprocessed Apollo 11 SSTV signal were erased and reused by NASA in the early 1980s. This was according to NASA's procedures, as they were facing a major data tape shortage at that time. Although the researchers never found the telemetry tapes they were looking for, they did discover the best visual quality NTSC videotapes as well as super 8 movie film taken of a video monitor in Australia, showing the SSTV transmission before it was converted. These visual elements were processed in 2009, as part of a NASA approved restoration project of the first Moonwalk. At a 2009 news conference in Washington, D.C., the research team released its findings regarding the tapes' disappearance. They also partially released newly enhanced footage obtained during the search. Lowry Digital completed the full Moonwalk restoration project in late 2009. Image:HoneysucklePolaroid.jpg Image:Apollo11TV5.jpg Image:Apollo11Honeysuckle.jpg == Background == Limited radio bandwidth was available to transmit the video signal, which needed to be multiplexed with other communication and telemetry channels beamed from the Lunar Module back to the Earth. Therefore, Apollo 11's moonwalk video was transmitted from the Apollo TV camera in a monochrome SSTV format at 10 frames per second (fps) with 320 lines of resolution, progressively scanned. These SSTV signals were received by radio telescopes at Parkes Observatory, the Goldstone tracking station and Honeysuckle Creek tracking station. The camera's video format was incompatible with existing NTSC, PAL and SECAM broadcast television standards. It needed to be converted before it could be shown on broadcast television networks. This live conversion was crude, essentially using a video camera pointing at a high-quality 10-inch TV monitor. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Apollo 11 missing tapes」の詳細全文を読む スポンサード リンク
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