[6] In the 1950s, the United States Department of Defense (DoD)'s Advanced Research Projects Agency (ARPA) was seeking a means to detect missiles in Earth's ionosphere.

On November 6, 1959, Cornell University entered into a contract with ARPA to carry out development studies for a large-scale ionospheric radar probe.

[12] In 2011, NSF delisted Arecibo as an FFRDC, which allowed the observatory to seek funding from a wider variety of sources; the agency also replaced Cornell as the site operator with a team led by SRI International.

The remaining support cables from one tower failed around 7:56 a.m. local time on December 1, 2020, causing the receiver platform to fall into the dish and collapsing the telescope.

[27] The investigation concluded that "a combination of low socket design margin and a high percentage of sustained loading revealed an unexpected vulnerability to zinc creep and environments, resulting in long-term cumulative damage and progressive zinc/wire failure".

Opened in 1997, the Ángel Ramos Foundation Visitor Center features interactive exhibits and displays about the operations of the radio telescope, astronomy and atmospheric sciences.

[30] The center is named after the financial foundation that honors Ángel Ramos, owner of the El Mundo newspaper and founder of Telemundo.

The Foundation provided half of the funds to build the Visitor Center, with the remainder received from private donations and Cornell University.

The purposes of the center are to increase public interest in astronomy, the observatory's research successes, and space endeavors.