[UPDATED 2020-12-02 @1609 UTC] The 900-ton instrument platform of the 305-meter radio telescope at Arecibo Observatory in Puerto Rico fell some 400 feet Tuesday morning, crashing into the huge, already-damaged dish below, the National Science Foundation (NSF) reported in a December 1 Tweet. “No injuries were reported,” NSF said, adding that it is still assessing the situation. “Our top priority is maintaining safety.” The calamity not only was a final and fatal blow for the observatory but for the people of Puerto Rico.

Head of Telescope Operations Angel Vazquez, WP3R, called December 1 “indeed a sad day.” Vazquez was in the Observatory’s control room at the time, salvaging important instruments when he heard a loud noise.

“At around 7:55 AM, the platform collapsed due to the extra stress on the existing cables because of the main cable failure in November. Strands were starting to pop all weekend long, and it was just a matter of time,” he told ARRL. “It came off the easternmost tower (T4) and took about 15 seconds. The azimuth arm that housed the dome came off the track, fell into the dish a little north of center and the triangle was pulled by the other existing cables to the northwestern part of the dish. The tops of the towers broke as well. This was a 900-ton platform, and the dome was smashed like an eggshell.”

The towers supported the massive instrument platform, which was suspended on cables above the dish. On August 10, an auxiliary cable that helped to support the platform snapped and fell, causing a 100-foot gash in the reflector dish. After an extensive evaluation, NSF announced on November 19 that the damaged radio telescope — in service for nearly 60 years — was beyond repair and would be decommissioned due to safety concerns. Arecibo, which, among other accomplishments had contributed to the observation of black holes, was the second-largest radio telescope in the world.

The iconic dish has served as a backdrop for several science fiction movies. The Arecibo Observatory Amateur Radio Club, KP4AO, is headquartered at the research facility, and several other radio amateurs are employed there in addition to Vazquez. Operations at the world-famous observatory have been managed by the University of Central Florida (UCF).

Engineers were ready to implement emergency structural stabilization of the auxiliary cable system, but while arranging delivery of two replacement cables and two temporary cables, a main cable broke on the same tower on November 6. Based on the stresses borne by the second broken cable, engineers concluded that the remaining cables were likely weaker than originally projected.

Antenna designer and electrical engineer Jim Breakall, WA3FET, who conducted research at the world-famous facility over more than 45 years, told ARRL that his experience with Arecibo began in 1974 when he was a student, and he worked on the first HF ionospheric heating design and calibration of the dish for ionospheric research. He also conducted amateur radio moonbounce experiments there. Later, he designed feeds for radio astronomy and designed and built the HF ionosphere modification facility that fed the dish with a dipole array at the bottom of the huge dish, after Hurricane Georges destroyed the first HF facility some 10 miles away in 1998.

“I built a super contest station on my farm there about 2 miles away using Angel’s call sign, WP3R. It got destroyed in Hurricane Maria in 2017,” Breakall recounted. “I also was on the team for KP4AO in 2010 for EME [moonbounce] and my photo was on the cover of QST with Joe Taylor, K1JT.”

“I was prepared for this, but still never wanted to hear it,” Breakall told ARRL. “It is like losing a loved one when you know they are dying. Wow. Who would have ever believed it.”

NSF said it was saddened by the latest development regarding the aging radio telescope. “As we move forward, we will be looking for ways to assist the scientific community and maintain our strong relationship with the people of Puerto Rico.”