Arecibo Observatory collapses
ON NOVEMBER 19, 2020, the U.S. National Science Foundation (NSF) announced it would decommission the famed Arecibo Observatory in Puerto Rico. The statement came following a three-month period that saw the failure of first an auxiliary cable, then a main support cable, both connecting the telescope’s 900-ton receiving platform to one of three support towers. Engineers had determined repairs could not be made without risking further damage to the telescope or, more importantly, the safety of construction workers and facility staff.
NSF planned to execute a controlled demolition. But the observatory had other ideas. Around 8 A.M. local time Dec. 1, the receiving platform fell nearly 500 feet (152 meters) into the 1,000-foot-wide (305 m) dish below, destroying both with a crash.
“The loss of Arecibo was shocking — there were several virtual online vigils held in mourning by those who worked with the telescope, and for the broader radio astronomy community,” says Yvette Cendes, a postdoctoral researcher and radio astronomer at the Harvard-Smithsonian Center for Astrophysics in Cambridge, Massachusetts.
For 57 years, Arecibo’s huge white dish was an icon amid the lush green jungle.
More than that, its scientific legacy stood unmatched. The observatory had several historic notches in its belt, from spotting the first binary pulsar system in 1974 to identifying the first extrasolar planets in 1992. And although Arecibo had in recent years been surpassed in size by the Five-hundred-meter Aperture Spherical radio Telescope (FAST) in China, the newer facility is not a direct replacement. FAST currently lacks Arecibo’s planetary radar capability, which is needed to characterize the size and spin of near-Earth asteroids.
Arecibo was also a vital link in the North American Nanohertz Observatory for Gravitational Waves, or NANOGrav. This network of observatories is searching for gravitational waves by studying how passing ripples in space-time affect the signals Earth receives from pulsars. Although NANOGrav’s ability to detect gravitational waves in the future will certainly diminish without Arecibo’s contributions, researchers do still have a wealth of past observations with the facility they can refer back to, according to the collaboration’s website.
Naturally, researchers are looking to what comes next. On April 1, the National Astronomical Observatories of the Chinese Academy of Sciences opened FAST to the international community, accepting proposals from researchers around the world. Around the same time, “there was a call for white papers on ideas on how to replace Arecibo, and what to do with the site in general,” Cendes says.