Declass 2 (2002) = KH-7 and KH-9 Global Camera Photos: 1963 - 1980

Keyhole (KH) satellite systems KH-7 and 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 of military applications.

The KH-7 surveillance system was a high resolution imaging system that was operational from July 1963 to June 1967. Approximately 18,000 black-and-white images and 230 color images are available from the 38 missions flown during this program. Key features for this program were larger area of coverage and improved ground resolution. The cameras acquired imagery in continuous lengthwise sweeps of the terrain. KH-7 images are 9 inches wide, vary in length from 4 inches to 500 feet long, and have a resolution of 2 to 4 feet.

The KH-9 mapping program was operational from March 1973 to October 1980 and was designed to support mapping requirements and exact positioning of geographical points for the military. This was accomplished by using image overlap for stereo coverage and by using a camera system with a reseau grid to correct image distortion. The KH-9 framing cameras produced 9 x 18 inch imagery at a resolution of 20-30 feet. Approximately 29,000 mapping images were acquired from 12 missions.

The images have variable scales and quality. Cloud cover is common. The digital products are produced from a duplicate negative film source. More than 40 percent of the imagery contains significant cloud cover. The use of browse imagery gives the user the opportunity to review a reduced resolution image 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.nara.gov) National Archives and Records Administration (NARA).

Keyhole（KH）卫星系统的KH-7与KH-9型号通过望远相机系统获取地球表面影像，并借助回收舱运输已曝光胶片。回收舱（或称吊舱）脱离轨道后以降落伞降落至地面，再由航空器完成回收。后续将对已曝光胶片进行冲洗，并针对各类军事应用场景对影像开展分析。

KH-7侦察系统为高分辨率成像系统，服役周期为1963年7月至1967年6月。该项目共执行38次任务，现存约18000幅黑白影像与230幅彩色影像。本项目的核心优势为覆盖范围更广、地面分辨率更优。相机以连续纵向条带扫描的方式获取地形影像。KH-7影像宽度为9英寸，长度范围为4英寸至500英尺，分辨率可达2至4英尺。

KH-9测绘项目服役周期为1973年3月至1980年10月，其设计初衷为满足军事测绘需求与地理点位的精确定位。该系统通过影像重叠实现立体覆盖，并搭载带有格网标记（reseau grid）的相机系统以校正影像畸变。KH-9画幅相机可生成分辨率为20至30英尺的9×18英寸影像。该项目共执行12次任务，累计获取约29000幅测绘影像。

本数据集影像存在可变比例尺与画质差异，云层遮挡较为常见。数字产品由副本负片源生成，超过40%的影像存在显著云层遮挡。浏览影像允许用户先查看低分辨率版本，以确认目标区域是否被覆盖并检查云层遮挡情况。原始胶片存档由美国国家档案与文件署（National Archives and Records Administration, NARA，官网：http://www.nara.gov）负责维护。