Last January, Science Magazine did a deep dive into the Arecibo collapse.
https://www.sciencemag.org/news/2021/01/how-famed-arecibo-telescope-fell-and-how-it-might-rise-again
“The telescope’s cables were designed with a safety factor of just over two, so everyday loads on the cables would be less than half of the load that would break them. That surprises Robert Lark, a civil engineer at Cardiff University, who says that bridge cables typically have safety factors of six or more.”
There’s a $400 million proposal for replacement, with a new design sporting 1000 9-meter dishes on a moveable platform that can tilt up to 45 degrees off the horizontal. The radar would be 4 times as powerful (which is good, because power declines with the 4th power of distance) and cover a wider field of view (also good, as they want to peer into the Milky Way’s galactic core).
Odds of funding are deemed slim. Planet Earth used to have 2 high powered radar astronomy observatories, which are useful for tracking killer asteroids. Now we have one:
Its website was last updated in January 2016:
OTOH, $400 million is a lot of money and planetary defense is boring. Besides, bad surprises rarely happen, and when they do we handle them well. Sure, we could probably make good use of lead times of 50 to 200 years, but some of us are betting men and I’m one of them. What’s the alternative?
More seriously, we know this project won’t come in under budget, if it happens. Still.