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Arecibo Observatory faces demolition after cable failures
November 19, 2020 William Harwood


The damaged dish at Arecibo Observatory. Credit: University of Central Florida

After withstanding hurricanes and earthquakes, playing central roles in movies like “GoldenEye” and “Contact,” Puerto Rico’s famed Arecibo Observatory, once the largest radio telescope in the world, will be demolished because of cable failures that left its huge detector platform too unstable to attempt repairs.

“After reviewing the engineering assessment, we have found no path forward that would allow us to do so safely,” said Sean Jones, assistant director for the Mathematical and Physical Sciences Directorate at the National Science Foundation.

“We know that a delay in decision making leaves the entire facility at risk of an uncontrolled collapse, unnecessarily jeopardizing people and also the additional facilities.”

Operated by the NSF through the University of Central Florida, the iconic observatory is made up of a fixed 1,000-foot-wide dish antenna built into a bowl-like depression that reflects radio waves or radar beams to a 900-ton instrument platform suspended 450 feet above by cables stretching from three support towers.

For 57 years, the observatory has played a leading role observing deep space targets, bodies in the solar system and, using powerful lasers, the composition and behavior of Earth’s upper atmosphere.

But the beginning of the end came on Aug. 10 when an auxiliary cable installed in the 1990s pulled free of its socket on one support tower and crashed onto the dish below, ripping a 100-foot-long gash.

Engineers were developing repair plans when one of the main 3-inch-wide cables attached to the same tower unexpectedly snapped on Nov. 6, causing the instrument platform to tilt and putting additional stress on the remaining cables.

An analysis showed the cable failed in calm weather at about 60 percent of of its minimum breaking strength. Inspections of other cables showed fresh wire breaks and slippage in several auxiliary cable sockets that were added to the structure in the 1990s.

An engineering firm hired by the University of Central Florida to assess the structure concluded it would be unsafe to proceed with repairs. Even stress tests to determine the strength of the remaining cables could trigger a catastrophic collapse.

Instead, engineers recommended a controlled demolition, bringing down the suspended instrument platform in a way that will prevent damage to other structures at the periphery of the dish by making sure the towers themselves don’t collapse and by ensuring no cables whip into those structures.

“The telescope is at serious risk of an unexpected, uncontrolled collapse,” said Ralph Gaume, director of NSF’s Division of Astronomical Sciences. “According to engineering assessment, even attempted stabilization, or testing the table could result in accelerating the catastrophic failure.

“Engineers cannot tell us the safety margin of the structure, but they have advised NSF that the structure will collapse in the near future on its own.”

Plans for bringing down the instrument platform have not yet been finalized and it’s not yet known whether explosives will be used in a controlled demolition or whether it might be possible to somehow lower the platform to the dish below.

However it plays out, the 1,000-foot-wide telescope will essentially be destroyed. While the laser facility and visitor’s center will hopefully be preserved, the radio telescope itself will be no more.

“For 57 years, this facility has served as a resource for radio astronomy, solar system radar astronomy, space and atmospheric science,” said Gaume. “The Arecibo 305-meter telescope had powerful, unique capabilities, advantages especially valuable.

“That said, we’re confident in the resilience of the astrophysics community and that NSF will be encouraging other facilities to work directly with the Arecibo scientific community and investigators to provide them with appropriate support now.”

Completed in 1963, the Arecibo Observatory was the largest single-dish radio telescope in the world until China’s Five hundred meter Aperture Spherical Telescope, or FAST, began operations in 2016.

The dish antenna, made up of nearly 40,000 aluminum panels, was built into a depression left by a sinkhole. While the dish itself only moves with Earth’s rotation, the instrument platform features a moveable receiver pallet that allows astronomers to “look” at targets up to 40 degrees away from the telescope’s vertical axis.

Along with a half century of astronomical observations, the observatory has been featured in movies ranging from the James Bond thriller “GoldenEye” to “Contact,” based on Carl Sagan’s novel about first contact with aliens.

The observatory also played a role in the search for extraterrestrial intelligence, or SETI. In 1974, the dish was used to beam a crude message into deep space. More recently, the observatory provided the data used by the SETI@home project, which looked for signals using the computing power of thousands of on-line personal computers.


Source: https://spaceflightnow.com/2020/11/19/arecibo-observatory-faces-demolition-after-cable-failures/

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Odp: [SFN] Arecibo Observatory faces demolition after cable failures
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Jedni laduja na Ksiezycu a u innych wszystko sie wali ...
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Odp: [SFN] Arecibo Observatory faces demolition after cable failures
« Odpowiedź #2 dnia: Grudzień 03, 2020, 01:24 »
Arecibo Observatory collapses as scientists lament loss of deep space radar
December 1, 2020 Stephen Clark


The instrument platform of the Arecibo Observatory — seen here in an earlier photo — collapsed onto the telescope’s dish Dec. 1. Credit: National Science Foundation

The 900-ton suspended platform of Puerto Rico’s famed Arecibo Observatory collapsed Tuesday after cable failures, crashing into the radio telescope’s iconic dish and shattering a research instrument used for nearly 60 years to study pulsars, galaxies, planets, and asteroids that might threaten Earth.

The National Science Foundation, which owns the facility, confirmed the instrument deck fell around 7:55 a.m. local time Tuesday in Puerto Rico, “resulting in damage to the dish and surrounding facilities.”

No injuries were reported in the accident.

The NSF announced last month that it would decommission and demolish the observatory after a series of cable breaks rendered the facility unsafe. The first suspension cable snapped Aug. 10, causing a gash in the observatory’s 1,000-foot (305-meter) reflecting dish.

While officials assessed repair options, another cable broke Nov. 6. Inspections and analyses showed other cables were in danger of failing, and the NSF announced Nov. 19 that engineers recommended a controlled demolition of the structure, which officials said then was in danger of a collapse on its own in the near future.

The collapse happened Tuesday before crews could start the demolition. The failure shattered sensitive radio receivers and a planetary radar instrument as the platform fell onto the dish some 450 feet (137 meters) below.

Completed in 1963, the observatory was the second-largest radio telescope in the world and featured in films like “Contact” and “GoldenEye.” The giant dish reflected faint radio signals from deep space onto sensors suspended on the instrument platform.


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Muy tristes las fotos desde el Observatorio de Arecibo.



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“We are saddened by this situation but thankful that no one was hurt,” said Sethuraman Panchanathan, NSF’s director, in a statement. “When engineers advised NSF that the structure was unstable and presented a danger to work teams and Arecibo staff, we took their warnings seriously and continued to emphasize the importance of safety for everyone involved.

“Our focus is now on assessing the damage, finding ways to restore operations at other parts of the observatory, and working to continue supporting the scientific community, and the people of Puerto Rico,” Panchanathan said.

“Initial findings indicate that the top section of all three of the 305-meter telescope’s support towers broke off. As the 900-ton instrument platform fell, the telescope’s support cables also dropped,” the NSF said in a statement.

Officials said the observatory’s learning center also “sustained significant damage” from the falling cables.

Saddened by the collapse, astronomers shared memories of their work at Arecibo on social media. Some scientists called on the observatory to be rebuilt.

“Many scientists have worked on this telescope over the last 50-plus years,” said Thomas Zurbuchen, head of NASA’s science directorate. “Those observations have provided tremendous insights in some of the most energetic parts of our universe, pulsars. They have provided important planetary science looking at the moon and Mars … And also they have contributed tremendously to planetary defense objectives.”

With a planetary radar, Arecibo Observatory allowed scientists to characterize the shape, make-up, and orbits of asteroids on trajectories that intersect Earth’s orbit.



These radar images of near-Earth asteroid 3200 Phaethon were generated by astronomers at the National Science Foundation’s Arecibo Observatory on Dec. 17, 2017. Credit: Arecibo Observatory/NASA/NSF

“Our hearts are heavy about this,” Zurbuchen said Tuesday in a meeting of the NASA Advisory Council’s Science Committee.

Lindley Johnson, NASA’s planetary defense officer, said the loss of the Arecibo Observatory will not affect scientists’ ability to detect asteroids that might be on a collision course with Earth.

NASA has a radar imager at its Goldstone tracking station in California that can see a wider swath of the sky with finer resolution than Arecibo.

“But Arecibo had the range, so some of the planetary science at more distant objects will probably suffer the greatest impact,” J0hnson said Monday, before the observatory’s collapse. “We will no longer have the range that Arecibo offered.

“It’s really time to be looking at the next generation of planetary radar capabilities,” Johnson said. “Large dish radio telescopes is probably not the way to go with modern capabilities and processing. An array dish approach is probably the way.”



Damage to the Arecibo Observatory after the Dec. 1 collapse of its instrument platform. Credit: National Science Foundation

With its high-power transmitter, Arecibo’s radar could study objects in the asteroid belt and deeper into the solar system.

“It all comes down to power, really,” Johnson said. “Arecibo had the higher-power transmitter than Goldstone does, so the opportunities may not be as great with just Goldstone.”

Goldstone’s antenna is also used to communicate with deep space probes, so any scientific radar observations must be scheduled around spacecraft requirements, Johnson said.

The Arecibo Observatory is managed by the University of Central Florida. The NSF said it will continue to authorize UCF to pay Arecibo staff and continue research work at Arecibo, including the repair of a smaller telescope for radio astronomy research and other infrastructure repairs to address damage from Hurricane Maria in 2017.

“We knew this was a possibility, but it is still heartbreaking to see,” said Elizabeth Klonoff, UCF’s vice president for research. “Safety of personnel is our number one priority. We already have engineers on site to help assess the damage and determine the stability and safety of the remaining structure. We will continue to work with the NSF and other stakeholders to find ways to support the science mission at Arecibo.”


Source: https://spaceflightnow.com/2020/12/01/arecibo-observatory-collapses-as-scientists-lament-loss-of-deep-space-radar/
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Odp: [SFN] Arecibo Observatory faces demolition after cable failures
« Odpowiedź #3 dnia: Grudzień 03, 2020, 17:33 »
Tak to sie zaczelo:

a tak skonczylo:
https://twitter.com/DeborahTiempo/status/1334530900655304706
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Odp: [SFN] Arecibo Observatory faces demolition after cable failures
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Odp: [SFN] Arecibo Observatory faces demolition after cable failures
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tu jest to samo z początku plus dalej jest pokazana jedna z wież z drona z bliska.

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Odp: [SFN] Arecibo Observatory faces demolition after cable failures
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https://players.brightcove.net/679256133001/EkLWnGuil_default/index.html?videoId=6213883083001
to samo z innego zrodla i chyba z lepsza jakoscia. Z powazaniem
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Odp: [SN] Arecibo replacement could support space situational awareness
« Odpowiedź #6 dnia: Styczeń 24, 2021, 17:45 »
Arecibo replacement could support space situational awareness
by Jeff Foust — January 22, 2021


Arecibo Observatory's 305-meter radio telescope before its collapse in December 2020. A potential replacement for that telescope could be used for space object tracking as well as scientific research. Credit: NAIC - Arecibo Observatory, a facility of the NSF

WASHINGTON — A proposal to replace the giant radio telescope at Arecibo Observatory in Puerto Rico with a new facility suggests it could be used for tracking space objects as well as for scientific research.

Plans for a potential replacement of the 305-meter radio telescope at Arecibo, whose observing platform collapsed Dec. 1, are still in their early phases. One proposal, developed by observatory staff and submitted to the National Science Foundation (NSF) in a recent white paper, calls for replacing the giant dish with an array of up to 1,000 small dishes, each nine meters across, on a platform spanning the current dish.

“As we move into the future, we feel that phased arrays are probably the right way to go, rather than continue to focus on large single-dish elements,” said Francisco Cordova, director of Arecibo Observatory, during a presentation at a Jan. 21 meeting of a committee supporting the ongoing planetary science decadal survey by the National Academies.

The concept in the white paper would double the sensitivity of the single-dish radio telescope and increase sky coverage by 250% compared to the fixed dish, as well as incorporate a new radar system. “From our perspective as the operator, we feel that the 305-meter was really an invaluable tool,” he said. “But, any future visions of the site really need to be centered around the development of a next-generation instrument.”

That new concept, Cordova said, could serve applications beyond astronomy and planetary science. One of the potential applications he listed on a slide in his presentation was space situational awareness (SSA).

“That particular capability really comes embedded into the concept of the next-generation telescope,” he said when asked by the committee about SSA. There has been strong interest by the “DOD community” for years in using Arecibo for SSA. “We’ve actually had many plans to incorporate those kinds of capabilities previously into the 305-meter, but we weren’t able to do it at the capacity we wanted to because of the limited sky coverage.”

The increased sky coverage of the proposed array, Cordova suggested, made it more useful for SSA applications. “That is something that would be baked into the instrument,” he said. “It is an area where we’ve gotten a lot of interest throughout the years, so we want to make sure that is also part of its capabilities.”

Cordova didn’t elaborate on that past interest by the Defense Department in Arecibo for SSA activities. The military has long operated its own radars for tracking objects, such as the new Space Fence. One company, LeoLabs, has established its own set of radars to support space traffic management services it offers commercially. None of these facilities are on the same scale as Arecibo.

It will be up to NSF to decide whether to build a replacement for Arecibo’s giant dish, and if so what form it will take and what applications it will serve. Congress, in its fiscal year 2021 omnibus appropriations bill, directed the NSF to provide a report within 60 days of the bill’s Dec. 27 enactment on options for repairing or replacing the telescope.

The discussion about Arecibo was part of a broader examination of planetary radar capabilities, used to study near Earth asteroids and other solar system objects. Arecibo was one of the few observatories in the world with a planetary radar capability, funded by NASA as part of its planetary defense program to refine the orbits of asteroids and determine their size and shape.

The loss of Arecibo leaves planetary scientists with primarily just a single radar at a NASA Deep Space Network antenna in Goldstone, California. “New planetary radar instruments are desperately needed,” Anne Virkki, a planetary scientist at the University of Central Florida and lead of the planetary radar science group at Arecibo Observatory, told the committee. “Relying on just Goldstone is not a long-term solution.”

“The two telescopes were highly complementary in terms of their capabilities,” said Lance Benner of the Jet Propulsion Laboratory, comparing Arecibo and Goldstone. Arecibo was 20 times more sensitive and could detect objects as twice the distance of Goldstone’s radar, while Goldstone could see more of the sky.

“Right now, we basically can’t replace it,” he said of Arecibo’s planetary radar. “There are no existing facilities that come even close to its capabilities that are currently available.”

However, there are radio telescopes that could provide some planetary radar capabilities in the relatively near future. The Green Bank Observatory in West Virginia tested a radar system on its 100-meter radio telescope in November, bounding radar signals off the moon that were then received by other antennas.

That test was intended to be a demonstration for a future, more powerful radar system, Karen O’Neil, director of Green Bank Observatory, told the committee. That later system could enter service as soon as 2024, she said, although it is still in the project definition phase.

The observatory is still working to secure funding for that radar. “We are talking in the tens of millions of dollars for the overall radar system,” she said.

An array of radio antennas with a radar would be even more expensive. A study by Caltech’s Keck Institute for Space Studies last year on next-generation planetary radar systems examined concepts for arrays of dozens to a hundred or more dishes, each tens of meters across. Such a system, Benner said, would likely cost half a billion dollars or more.


Source: https://spacenews.com/arecibo-replacement-could-support-space-situational-awareness/

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Odp: [SN] Arecibo replacement could support space situational awareness
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