The minimum size of KH-11 mirrors has been common knowledge for many years now, since it influenced the Hubble telescope. From the book Power To Explore -- His

The minimum size of KH-11 mirrors has been common knowledge for many years now, since it influenced the Hubble telescope. From the book Power To Explore -- History of Marshall Space Flight Center 1960-1990: > "In addition, changing to a 2.4-meter mirror would lessen fabrication costs by using manufacturing technologies developed for military spy satellites." PDF: https://web.archive.org/web/20170205104821/https://history.msfc.nasa.gov/book/chpttwelve.pdf https://web.archive.org/web/20170205104821/https://history.m... They're 2.4 meters at their smallest, with later KH-11's possibly being larger. But even 2.4 meters is enough to get way better image quality than has been publicly released.