More accurately, the call was a microwave radio signal, and rather than expecting a message back, scientists were trying to create what became known as moon bounce, or earth-moon-earth (EME) communications.
|The Diana antenna, made from four|
existing conventional radar antennas.
Colonel John DeWitt and his Camp Evans-based team were charged with the task in the closing months of the war. Before they could work on detection, however, they had to prove that a radio signal could pierce the earth's atmosphere as the V1 and V2 could. A few years earlier, a British communications scientist had theorized that existing technology would be capable of bouncing microwave signals off the moon which, at 238,900 miles away, would serve as an ideal target.
In September 1945, Evans Signal Labs personnel got to work designing and building the necessary equipment: a sufficiently powerful transmitter and receiver along with an antenna array to capture the return signal. (If you're an engineer, astronomer or physicist, you might enjoy reading a more technical description and schematics written by one of the participants.) Three months later, their initial tests were hampered by a series of malfunctions and outright equipment failures.
A new year and heavily redesigned equipment brought better results. At moonrise on January 10, 1946, they succeeded, receiving a return signal 2.5 seconds after transmission. It took some time to determine the right conditions to repeat the achievement, but Evans professionals had made theory a reality.
The first experiment in radio astronomy, Project Diana's impact reached far beyond national defense. Many consider that first successful radio bounce to be the true birth of the space program. Had scientists not proven that human-created radio signals could leave our atmosphere, people on Earth would not have be able to communicate with astronauts in orbit or on the moon. Skylab and the International Space Station would have been pipe dreams. Nor would we have been able to receive signals from long-distance spacecraft like Voyager I and II, which have been returning information to us by radio since their launches in 1977.
And, of course, this experiment on The Big Bang Theory would have been totally impossible.
The original Diana antenna no longer exists, but a support building remains at Camp Evans, now the site of the InfoAge Science History Learning Center and Museum. As we discovered during our visit last July, the expansive yet utilitarian-looking property holds a wealth and breadth of history well worth exploring.