Declass 3 (2013) = USGS Subset of Hexagon Missions - KH-9: 1971 - 1984

Keyhole (KH) satellite systems- KH-9 acquired photographs of the Earth's surface with a telescopic camera system and transported the exposed film through the use of recovery capsules. The capsules or buckets were de-orbited and retrieved by aircraft while the capsules parachuted to earth. The exposed film was developed and the images were analyzed for a range military applications.

The Keyhole (KH) satellite system KH-9 (Hexagon) operated between 1971 and 1984. The imagery generated are of historical interest and expected to support current scientific research on climate change and related fields of inquiry. Almost all of the imagery from this camera was declassified in 2012 as a continuation of Executive Order 12951, the same order that declassified CORONA. A subset of this declassified data was transferred to the U.S. Geological Survey's Earth Resources Observation and Science (EROS) Center. Please check the coverage map in EarthExplorer to verify the extent of coverage for the subset of images available from EROS. The Available images are primarily over the United States, Antarctica, and the Arctic Circle.

The KH-9 program was designed to support mapping requirement and exact positioning of geographical points for the military. The KH-9 panoramic cameras captured high resolution (2-4 feet) images and the terrain camera captured high resolution (2-4 feet) images and the terrain camera captured moderate resolution (20-30 feet) images. High resolution images were acquired on 6.5 inch wide variable length film. The moderate resolution terrain camera acquired images that were printed to 9 inch wide variable length film.

The digital products are produced from a duplicate positive film source. The use of browse imagery provides an opportunity to determine if the area of interest is covered and to check for cloud cover. The original film sources are maintained by the (http://www.archives.gov) National Archives and Records Administration (NARA).

锁眼（Keyhole, KH）卫星系统——KH-9型卫星搭载望远相机系统获取地球表面影像，并通过回收舱传输已曝光胶片。回收舱（又称胶片桶）脱离轨道后以降落伞降落至地面，随后由飞机完成回收。已曝光胶片将被冲洗，所得影像将用于各类军事应用场景。

锁眼（Keyhole, KH）系列卫星中的KH-9型（Hexagon）卫星运行于1971年至1984年间。该卫星所获取的影像具有历史研究价值，有望为当前气候变化及相关领域的科学研究提供支撑。2012年，该相机拍摄的几乎全部影像依据《第12951号行政命令》——即解密科罗纳（CORONA）项目影像的同一行政命令——完成解密。部分解密数据已移交至美国地质调查局（U.S. Geological Survey）的地球资源观测与科学（EROS）中心。用户可通过EarthExplorer平台中的覆盖范围地图，核实EROS中心可提供的影像子集的覆盖范围。当前可获取的影像主要覆盖美国、南极洲以及北极圈区域。

KH-9项目旨在满足军方的测绘需求与地理点位精确定位要求。KH-9全景相机可获取高分辨率（2至4英尺）影像，地形相机则可分别获取高分辨率（2至4英尺）与中分辨率（20至30英尺）影像。高分辨率影像采用6.5英寸宽的可变长度胶片拍摄。中分辨率地形相机所获取的影像将冲印至9英寸宽的可变长度胶片上。

数字产品均基于正片拷贝源文件生成。通过浏览影像，用户可确认目标区域是否被覆盖，并检查云量遮挡情况。原始胶片源文件由美国国家档案与记录管理局（National Archives and Records Administration, NARA，http://www.archives.gov）保管。