Damage to the iconic Arecibo Observatory from an earthquake earlier this year has been repaired and the telescope is now back to full service. On January 13, 2014, the William E. Gordon radio telescope sustained damage following a 6.4 magnitude earthquake that was centered 37 miles northwest of Arecibo. A large cable that supports the telescope’s receiver platform had “serious damage,” according to Bob Kerr, the Director of the Arecibo Observatory.
“In an abundance of caution, telescope motion had been very limited since the earthquake,” said Kerr in a press release issued today. “Nevertheless, the telescope continued its science mission, including participation in a 10-day global ionospheric study in late January and continuing a productive search for pulsars in the sky above Arecibo.”
The platform hangs above the Arecibo dish, supported by cables. Via Cornell University.
The cable that was damaged was one of 18 cables that supports the 900-ton focal platform of the telescope. This particular cable was actually a known potential problem, Kerr told Universe Today in a previous interview. He said that during original construction of the telescope in 1962, one of the original platform suspension cables that was delivered to the observatory was too short, and another short cable section was “spliced” to provide sufficient reach to the platform.
“That cable segment and splice near the top of one of the telescope towers was consequently more rigid than the balance of the suspension system,” Kerr said. “When the earthquake shook the site, just after midnight on January 13, it is that short cable and splice that suffered damage.”
“You might say that our structural Achilles heel was exposed,” Kerr added.
Inspectors from New York’s Ammann & Whitney Bridge Construction, who have been inspecting the Arecibo observatory site since 1972, were brought in to access the situation and Kerr said a relatively low-cost (less than $100,000) repair option was designed and carried out, bringing the telescope back into full service as of March 13, exactly two months from when the earthquake occurred.
The Arecibo Observatory is operated by SRI International, teaming with Universidad Metropolitana and the Universities Space Research Association, in a cooperative agreement with the National Science Foundation.
The Arecibo Observatory’s 305 meter (1,000 ft) radio telescope is undergoing emergency repair after being damaged during a 6.4 magnitude earthquake on January 13, 2014. A large cable that supports the telescope’s receiver platform had “serious damage,” according to Bob Kerr, the Director of the Arecibo Observatory.
“A protocol structural survey following the January 13 earthquake revealed serious damage to [a] short cable section, with apparent breach of several cable strands,” Kerr told Universe Today via email. “An experienced structural engineering firm was brought to assess the damage, and to consider repair options.”
The earthquake’s epicenter was located in the ocean about 60 kilometers (37 miles) northwest of Arecibo and was one of the largest to hit Puerto Rico in several years. The quake caused some floor cracking in buildings and homes on the island, as well as power outages, but no major damages or injuries, officials said. There were, however, at least 70 aftershocks with at least three of a magnitude 3.5 or greater.
The platform hangs above the Arecibo dish, supported by cables. Via Cornell University.
The famous radio observatory is located near Puerto Rico’s north coast, and opened in 1963. It was built inside a depression left by a sinkhole and is the largest curved focusing dish on Earth. The dish’s surface is made of thousands of perforated aluminum panels, each about 1 by 2 meters (3 by 6 feet), supported by a mesh of steel cables. The receiver is on a 900-ton platform suspended 137 meters (450 feet) above the dish by 18 cables running from three reinforced concrete towers.
It was one of these 18 cables that was damaged, and this particular cable was actually a known potential problem. Kerr said that during original construction of the telescope in 1962, one of the original platform suspension cables that was delivered to the observatory was too short, and another short cable section was “spliced” to provide sufficient reach to the platform.
“That cable segment and splice near the top of one of the telescope towers was consequently more rigid than the balance of the suspension system,” Kerr said. “When the earthquake shook the site, just after midnight on January 13, it is that short cable and splice that suffered damage.”
“You might say that our structural Achilles heel was exposed,” Kerr added.
Inspectors from New York’s Ammann & Whitney Bridge Construction, who have been inspecting the Arecibo observatory site since 1972, were brought in to access the situation. Kerr said a relatively low-cost (less than $100,000) repair option was designed, and materials are now being procured to complete a repair that is expected to bring the telescope back into full service.
“While the project awaits full review by the National Science Foundation, necessary steel materials for the repair are being shipped to the Observatory at this writing,” Kerr said. “Our estimated completion date for this project is March 11, 2014.”
This repair is considered temporary, however, and Kerr said a more comprehensive long-term cable repair design is being developed.
But the repair to the cable is by no means easy. The Arecibo Observatory maintenance staff will be doing the repairs themselves, working high above the ground on the 900-ton steel suspension bridge-like suspension system.
Kerr said they hope to complete this emergency repair “as expeditiously and safely as possible,” and that “it is testimony to the remarkable expertise, capability, and bravery of the Arecibo staff. I am dubious that a parallel capability exists at any other U.S. science facility.”
In the meantime, the telescope is being used only sparingly and with an “abundance of caution,” using only limited motion of the telescope. Kerr said that despite the damage, the telescope was able to continue its science mission by participation in a ten-day global ionospheric study in late January, in addition to continuing a search for pulsars in the sky above Arecibo, and searching for fast radio bursts (FRBs). Because radio telescopes can work at all times of day and in all kinds of weather, the observatory normally operates 24 hours a day. The Angel Ramos Visitor Center at the Observatory was closed for a few days, but reopened on January 22, with normal access and visiting hours.
The Observatory is recognized as one of the most important national centers for research in radio astronomy, planetary radar and terrestrial aeronomy. During its 50-plus years of use, findings from Arecibo have contributed to better understanding of the Earth’s atmosphere, the Moon, asteroids, other planets, exotic stars, our galaxy, and the large-scale galactic structure of the universe. The facility was featured in the movies “Contact” and “Golden Eye,” as well as dozens or TV shows and books, and is one of the most popular tourist attractions in Puerto Rico.
It is operated by SRI International, teaming with The Universidad Metropolitana and the Universities Space Research Association, in cooperative agreement with the National Science Foundation.
The mighty Arecibo Radio Observatory is one of the most powerful radio telescopes ever built – it’s certainly the larger single aperture radio telescope on Earth, nestled into a natural sinkhole in Puerto Rico. We’re celebrating the 50th anniversary of the construction of the observatory with a special episode of Astronomy Cast.
An asteroid that recently passed by Earth is about twice as large as originally estimated, and it would have had serious global consequences if it had impacted Earth. Asteroid 2012 LZ1 was only discovered on June 10, 2012 by Rob McNaught at the Siding Spring Observatory in Australia. This Near Earth Object was thought to be fairly large, 502 meters (1,650 feet) wide, and quite bright. But astronomers using the planetary radar system at Arecibo Observatory were able to better determine the asteroid’s size, rotation rate and shape and found it to be about 1 kilometer (0.6 miles) wide and actually quite dark.
Scientists consider a kilometer-wide asteroid is at the size threshold that could set off an extinction-level event if it were to hit Earth.
“This object turned out to be quite a bit bigger than we expected, said Dr. Ellen Howell from Arecibo, “which shows how important radar observations can be, because we’re still learning a lot about the population of asteroids.”
2012 LZ1 sneaked by our planet at about 5.3 million km (3.35 million) miles away, or about 14 times the distance between Earth and the Moon on June 14, and it won’t be back in Earth’s vicinity again until June 12th, 2053, and then will be about 3 times as distant.
The Arecibo astronomers have determined it won’t be a threat to Earth for at least 750 years.
“The sensitivity of our radar has permitted us to measure this asteroid’s properties and determine that it will not impact the Earth at least in the next 750 years,” said Dr. Mike Nolan, Director of Planetary Radar Sciences at the Arecibo Observatory.
Several amateur astronomers were able to image 2012 LZ1, and the original thinking was that it was very bright. Instead, the new size determination suggests that 2012 LZ1 must be quite dark, reflecting only 2-4% of the light that hits it.
This is another reminder that we don’t know everything about all the potential asteroid threats that are out there, and more searches need to be done to find and track as many of the near Earth asteroid population as possible. Asteroid 2012 LZ1 has been classified as a Potentially Hazardous Asteroid, which are asteroids larger than approximately 100 meters that can come closer to our planet than 0.05 AU (7.4 million km, 4.65 million miles). As of now, none of the known PHAs is on a collision course with our planet, but both amateur and professional astronomers are finding new ones all the time, sometimes with just a few hours’ notice of a close approach.
Lead image caption: Asteroid 2012 LZ1 as seen by the Haleakala-Faulkes Telescope North on June 13, 2012. Credit: Nick Howes, Ernesto Guido & Giovanni Sostero.
