Fabled Arecibo Observatory to Be Shut Down After Twin Mishaps

The Arecibo Observatory space telescope on November 7, 2020. Photo: UCF/Handout via Reuters.

New Delhi: The Arecibo Observatory will close down – and its enormous structure dismantled – after 57 years, following two mishaps that left it on the brink of collapse.

The US National Science Foundation, which is in charge of the observatory in Puerto Rico, announced the decision on Thursday, November 19.

The Wire Science had previously reported how the failure of supportive cables had led the massive space telescope’s suspended dome platform to have become dangerously precarious.

This 900-tonne dome hangs 500 m above the vast dish of the telescope with the help of 18 thick steel cables attached to three concrete towers.

In August, one of these cables slipped and fell onto the dish below, resulting in a “gash” in the dish about 30 m long, having ripped off its reflective panels. This cable was an auxiliary one, which meant that the dome was not directly held up by it.

Another cable then broke earlier this month, tearing a new hole in the dish and damaging nearby cables. This was one of the four primary cables, each of which should have been capable of holding 544 tonnes – but “snapped under only” 283 tonnes, according to a report then by the Associated Press.

This new mishap exposed the dish to the risk of the entire dome collapsing on it. The dome, as described by National Geographic, is large enough to fit an entire house.

Photographs released by Planet and put together by The Wire Science shows the damage to the dish after mishaps in August (left) and November.

That the damage was significant is evident from satellite photographs released by Reuters, from a handout by Planet, an American company that operates a small fleet of Earth-observing satellites. The photo on the left, taken on September 15, shows a patch of green near the dish’s centre, where the gash lies. The photo on the right, from November 17, shows several more tears.

Engineers scrambled to devise a plan to preserve the crippled structure but have struggled to figure out why the initial cable failed.

An engineering firm hired by the University of Central Florida, which manages the observatory for NSF under a five-year and $20 million agreement, concluded in a report to the university last week “that if an additional main cable fails, a catastrophic collapse of the entire structure will soon follow.”

“NSF has concluded that this recent damage to the 305-meter telescope cannot be addressed without risking the lives and safety of work crews and staff,” Reuters quoted Sean Jones, assistant director of the Mathematical and Physical Sciences Directorate at NSF, as having said.

Citing safety concerns, the engineering firm had ruled out efforts to repair the observatory and recommended a controlled demolition.

“NSF has decided to begin the process of planning for a controlled decommissioning of the … telescope,” Jones said.

The Arecibo Observatory space telescope, which was damaged in August and again in November from broken cables which tore holes in the structure, is seen in Arecibo, Puerto Rico November 7, 2020. Photo: UCF/Handout via Reuters.

Ralph Gaume, the director of NSF’s astronomy division, told Science that the agency wants to preserve other instruments at the site, as well as the visitor and outreach centre.

Several science news outlets quoted managerial officials noting that the decision to dismantle the observatory hinged solely on safety concerns and that it doesn’t reflect on the telescope’s merit.

Nature reported that the telescope had been regularly upgraded, with several new instruments set to be installed in the coming years. “The telescope is in no way obsolete,” Christopher Salter, an astronomer at the National Radio Astronomy Observatory in West Virginia, who worked at Arecibo for years, told Nature.

Yet news of the observatory’s end isn’t likely to be welcome for scientists who have, for many decades, banked on it for observations of distant stars and galaxies, to spot potentially hazardous asteroids and to hunt for potential signatures of extraterrestrial life.

The observatory’s striking location – in the middle of a heavy forest – also made it a tourist spot and earned it several film appearances.

To quote from The Wire Science‘s previous report, “In 1974, a group of astronomers used the observatory to beam a signal containing information about Earth and its humans in the direction of the M13 globular star cluster.” While the observatory will soon cease to exist, its interplanetary message will live on – as will the memories of its use in astronomers’ archives.

(With Reuters inputs)

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