Famously, some spy-satellites from the KeyHole series developed and operated by the US National Reconnaissance Office, where similar in capabilities to the Hubble Space Telescope, but then pointed at the earth rather than out into the universe. What can you tell me about these satellites? What era were they developed? Are they still active, and what are their approximate capabilities thought to be?
The Keyhole series of spy satellite were launched between 1975 and 1982 by the US Department of Defense under contract to Boeing. They comprised a pair of satellites, known as KeyHole 1 (KH1) and KeyHole 2 (KH2), designed to gather intelligence information about strategic areas of the world including military installations, economic developments, political movements, and foreign affairs.

These satellites were equipped with cameras that could capture high-resolution images and video footage of countries around the world. According to NASA's article "NASA Images Of The Solar System - A Historical Overview", KH1 was also capable of taking detailed photographs of Earth's weather systems. By doing so, it was believed to provide valuable insights into climate change research.

However, the exact capabilities of these satellites may have been exaggerated for propaganda purposes during the Cold War, given their potential to reveal sensitive information. It is worth noting that advanced spying technologies continue to evolve, and many modern satellites have far greater abilities than those of the Keyhole series.