摘要
The weather was clear over the northwestern Soviet Union on 16 September 1967,offering excellent photographic conditions for the US spy satellite passing overhead.Part of a top secret pro-gram known as Corona,the satellite shot a strip of film and contin-ued its orbit.Whether those particular images provided any important Cold War intelligence is unknown,but more than 50 years later,they have proven crucial for Volker Radeloff,a pro-fessor of forest and wildlife ecology at the University of Wisconsin-Madison,who studies how land use patterns change over time.
