Using the Moon as an Echo [video]

> radio telescope

From the title I thought it might be about using lasers against lunar retroreflectors, passive arrangements of precise mirrors that (usually) reflect light back to its source.

https://en.wikipedia.org/wiki/List_of_retroreflectors_on_the...

My understanding is that before the development of observation satellites in the 1960s, radio echos from the Moon were used to detect nuclear explosions (testing or military use) from the far side of the Earth. Even if direct observations were not possible / were limited, so long as the Moon was observable both over the test site and a US-friendly (not necessarily US-based) receiving station, such signals could be detected.

The Arecibo’s site origins trace back to the 1950s, when Cornell University proposed its construction to the Department of Defense’s Advanced Research Projects Agency (ARPA), which is today known as the Defense Advanced Research Projects Agency (DARPA). A desire to better understand the composition of the ionosphere and how it might impact objects passing through, including ballistic missile reentry vehicles carrying nuclear warheads, was a key reason for its construction. At the time, ARPA was in charge of a broad ballistic missile defense program known as Project Defender. It was believed that nuclear warheads would produce a distinct signature when reentering the atmosphere, making it possible to distinguish them from decoys, so long as that signature could be quickly identified and categorized. The plan was to use the Arecibo Telescope to help gather general, but still valuable information about the ionosphere in support of this effort.

https://www.twz.com/37898/collapsed-arecibo-radio-telescope-...>

What a useful tool that saves me time. My weekend project this week was literally just writing a canon for modular synth that used a moon bounce for the second voice. I figured I could compose it with a delay set to 2.7sec, and then play with the clock via Maths for a performance- but their plugin sounds like this is more complex and interesting.

Lunar bounce canons could become an entire form arising from that 2.7sec constraint.

This is really cool. A small niche of ham radio operators perform EME (Earth Moon Earth) contacts all the time

Moon bounce was quite the thing as a ham radio operator in the 1960s and 1970s when I got started. I was trying to put together my own system for the world's first EME bounce on 220Mhz back then but was eventually beat out as life, and my first job out of school, got in the way.