posted 11-19-2020 10:49 AM               

NSF begins planning for decommissioning of Arecibo Observatory's 305-meter telescope due to safety concerns

Following a review of engineering assessments that found damage to the Arecibo Observatory cannot be stabilized without risk to construction workers and staff at the facility, the U.S. National Science Foundation will begin plans to decommission the 305-meter telescope, which for 57 years has served as a world-class resource for radio astronomy, planetary, solar system and geospace research.

The decision comes after NSF evaluated multiple assessments by independent engineering companies that found the telescope structure is in danger of a catastrophic failure and its cables may no longer be capable of carrying the loads they were designed to support. Furthermore, several assessments stated that any attempts at repairs could put workers in potentially life-threatening danger. Even in the event of repairs going forward, engineers found that the structure would likely present long-term stability issues.

"NSF prioritizes the safety of workers, Arecibo Observatory's staff and visitors, which makes this decision necessary, although unfortunate," said NSF Director Sethuraman Panchanathan. "For nearly six decades, the Arecibo Observatory has served as a beacon for breakthrough science and what a partnership with a community can look like. While this is a profound change, we will be looking for ways to assist the scientific community and maintain that strong relationship with the people of Puerto Rico."

Engineers have been examining the Arecibo Observatory 305-meter telescope since August, when one of its support cables detached. NSF authorized the University of Central Florida, which manages Arecibo, to take all reasonable steps and use available funds to address the situation while ensuring safety remained the highest priority. UCF acted quickly, and the evaluation process was following its expected timeline, considering the age of the facility, the complexity of the design and the potential risk to workers.

The engineering teams had designed and were ready to implement emergency structural stabilization of the auxiliary cable system. While the observatory was arranging for delivery of two replacement auxiliary cables, as well as two temporary cables, a main cable broke on the same tower Nov. 6. Based on the stresses on the second broken cable -- which should have been well within its ability to function without breaking -- engineers concluded that the remaining cables are likely weaker than originally projected.

"Leadership at Arecibo Observatory and UCF did a commendable job addressing this situation, acting quickly and pursuing every possible option to save this incredible instrument," said Ralph Gaume, director of NSF's Division of Astronomical Sciences. "Until these assessments came in, our question was not if the observatory should be repaired but how. But in the end, a preponderance of data showed that we simply could not do this safely. And that is a line we cannot cross."

The scope of NSF's decommissioning plan would focus only on the 305-meter telescope and is intended to safely preserve other parts of the observatory that could be damaged or destroyed in the event of an unplanned, catastrophic collapse. The plan aims to retain as much as possible of the remaining infrastructure of Arecibo Observatory, so that it remains available for future research and educational missions.

The decommissioning process involves developing a technical execution plan and ensuring compliance with a series of legal, environmental, safety and cultural requirements over the coming weeks. NSF has authorized a high-resolution photographic survey using drones, and is considering options for forensic evaluation of the broken cable -- if such action could be done safely -- to see if any new evidence could inform the ongoing plans. This work has already begun and will continue throughout the decommissioning planning. Equipment and other materials will be temporarily moved to buildings outside the danger zone. When all necessary preparations have been made, the telescope would be subject to a controlled disassembly.

After the telescope decommissioning, NSF would intend to restore operations at assets such as the Arecibo Observatory LIDAR facility -- a valuable geospace research tool -- as well as at the visitor center and offsite Culebra facility, which analyzes cloud cover and precipitation data. NSF would also seek to explore possibilities for expanding the educational capacities of the learning center. Safety precautions due to the COVID-19 pandemic will remain in place as appropriate.

Some Arecibo operations involving the analysis and cataloging of archived data collected by the telescope would continue. UCF secured enhanced cloud storage and analytics capabilities in 2019 through an agreement with Microsoft, and the observatory is working to migrate on-site data to servers outside of the affected area.

Areas of the observatory that could be affected by an uncontrolled collapse have been evacuated since the November cable break and will remain closed to unauthorized personnel during the decommissioning. NSF and UCF will work to minimize risk in the area in the event of an unexpected collapse. NSF has prioritized a swift, thorough process with the intent of avoiding such an event.

NSF recognizes the cultural and economic significance of Arecibo Observatory to Puerto Rico, and how the telescope serves as an inspiration for Puerto Ricans considering education and employment in STEM. NSF's goal is to work with the Puerto Rican government and other stakeholders and partners to explore the possibility of applying resources from Arecibo Observatory for educational purposes.

"Over its lifetime, Arecibo Observatory has helped transform our understanding of the ionosphere, showing us how density, composition and other factors interact to shape this critical region where Earth's atmosphere meets space," said Michael Wiltberger, head of NSF's Geospace Section. "While I am disappointed by the loss of investigative capabilities, I believe this process is a necessary step to preserve the research community's ability to use Arecibo Observatory's other assets and hopefully ensure that important work can continue at the facility."

Engineering summary

Arecibo Observatory's telescope consists of a radio dish 1,000 feet (305 meters) wide in diameter with a 900-ton instrument platform hanging 450 feet above. The platform is suspended by cables connected to three towers.

On Aug. 10, 2020, an auxiliary cable failed, slipping from its socket in one of the towers and leaving a 100-foot gash in the dish below. NSF authorized Arecibo Observatory to take all reasonable steps and use available funds, which amounted to millions of dollars, to secure the analysis and equipment needed to address the situation. Engineers were working to determine how to repair the damage and determine the integrity of the structure when a main cable connected to the same tower broke Nov. 6.

The second broken cable was unexpected -- engineering assessments following the auxiliary cable failure indicated the structure was stable and the planning process to restore the telescope to operation was underway. Engineers subsequently found this 3-inch main cable snapped at about 60% of what should have been its minimum breaking strength during a period of calm weather, raising the possibility of other cables being weaker than expected.

Inspections of the other cables revealed new wire breaks on some of the main cables, which were original to the structure, and evidence of significant slippage at several sockets holding the remaining auxiliary cables, which were added during a refit in the 1990s that added weight to the instrument platform.

Thornton Tomasetti, the engineering firm of record hired by UCF to assess the structure, found that given the likelihood of another cable failing, repair work on the telescope -- including mitigation measures to stabilize it for additional work -- would be unsafe. Stress tests to capture a more accurate measure of the remaining cables' strength could collapse the structure, Thornton Tomasetti found. The firm recommended a controlled demolition to eliminate the danger of an unexpected collapse.

"Although it saddens us to make this recommendation, we believe the structure should be demolished in a controlled way as soon as pragmatically possible, " said the recommendation for action letter submitted by Thornton Tomasetti. "It is therefore our recommendation to expeditiously plan for decommissioning of the observatory and execute a controlled demolition of the telescope."

UCF also hired two other engineering firms to provide assessments of the situation. One recommended immediate stabilization action. The other, after reviewing Thornton Tomasetti's model, concurred that there is no course of action that could safely verify the structure's stability and advised against allowing personnel on the telescope's platforms or towers.

"Critical work remains to be done in the area of atmospheric sciences, planetary sciences, radio astronomy and radar astronomy," UCF President Alexander N. Cartwright said. "UCF stands ready to utilize its experience with the observatory to join other stakeholders in pursuing the kind of commitment and funding needed to continue and build on Arecibo's contributions to science."

After receiving the contracted assessments, NSF brought in an independent engineering firm and the Army Corps of Engineers to review the findings. The firm NSF hired concurred with the recommendations of Thornton Tomasetti and expressed concern about significant danger from uncontrolled collapse. The Army Corps of Engineers recommended gathering additional photographic evidence of the facility and a complete forensic evaluation of the broken cable.

Given the fact that any stabilization or repair scenario would require workers to be on or near the telescope structure, the degree of uncertainty about the cables' strength and the extreme forces at work, NSF accepted the recommendation to prepare for controlled decommissioning of the 305-meter telescope.

posted 11-19-2020 05:09 PM               

NASA Statement on NSF's Planned Controlled Decommissioning of Arecibo Radio Telescope

On Nov. 18, NASA was informed by the National Science Foundation (NSF) that, after careful assessment and consideration, they have decided to decommission the 305m radio telescope at the Arecibo Observatory in Puerto Rico, which recently sustained structural damage from failed cables. The planetary radar capability at Arecibo, funded by NASA's Near-Earth Object (NEO) Observations Program, has served as one of two major planetary radar capabilities. It has allowed NASA to fully characterize the precise orbits, sizes, and shapes of some NEOs passing within radar range after they are discovered by wide-field optical telescope survey projects.

For decades, the facility has been an important emblem of Puerto Rico's commitment to international science research and education, and the discoveries enabled by Arecibo's 305m radio telescope will continue to inspire the next generation of explorers. While the 305m radio telescope is being decommissioned, the Arecibo facility and its STEM education and other assets will continue.

While NASA was not directly involved in the investigation of what led to the observatory's damage in August, the NSF communicated with stakeholders, including NASA, as their investigation proceeded. NASA respects the National Science Foundation's decision to put the safety of those who work, visit, and study at the historic observatory above all else. NASA has facilitated some engineering assistance from NASA Centers at NSF's request.

NASA's Goldstone Observatory in California, another planetary radar, recently returned to full operations after successful delivery and testing of a new klystron tube for its high-power transmitter. Radars such as those at Goldstone and Arecibo are used only to characterize known NEOs, not to discover previously unknown asteroids and comets, so NASA's NEO search efforts are not impacted by the planned decommissioning of Arecibo's 305m radio telescope.

posted 12-01-2020 08:35 AM               

The instrument platform of the 305m telescope at Arecibo Observatory in Puerto Rico fell overnight. No injuries were reported. NSF is working with stakeholders to assess the situation. Our top priority is maintaining safety. NSF will release more details when they are confirmed.

NSF is saddened by this development. 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.

posted 12-01-2020 01:31 PM               

Arecibo Observatory's 305-meter telescope suffers collapse

The instrument platform of the 305-meter telescope at Arecibo Observatory in Puerto Rico fell at approximately 7:55 a.m. Atlantic Standard Time Dec. 1, resulting in damage to the dish and surrounding facilities.

No injuries were reported as a result of the collapse. The U.S. National Science Foundation ordered the area around the telescope to be cleared of unauthorized personnel since the failure of a cable Nov. 6. Local authorities will keep the area cordoned off as engineers work to assess the stability of the observatory's other structures.

Top priorities are maintaining safety at the site, conducting a complete damage assessment as quickly as possible, and taking action to contain and mitigate any environmental damage caused by the structure or its materials. While the telescope was a key part of the facility, the observatory has other scientific and educational infrastructure that NSF will work with stakeholders to bring back online.

"We are saddened by this situation but thankful that no one was hurt," said NSF Director Sethuraman Panchanathan. "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."

The investigation into the platform's fall is ongoing. 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.

Preliminary assessments indicate the observatory's learning center sustained significant damage from falling cables.

Engineers arrived on-site today. Working with the University of Central Florida, which manages the observatory, NSF expects to have environmental assessment workers on-site as early as tomorrow. Workers at the observatory will take appropriate safety precautions as a full assessment of the site's safety is underway.

NSF intends to continue to authorize UCF to pay Arecibo staff and take actions to continue research work at the observatory, such as repairing the 12-meter telescope used for radio astronomy research and the roof of the LIDAR facility, a valuable geospace research tool. These repairs were funded through supplemental congressional appropriations aimed at addressing damage from Hurricane Maria.

Once safety on site is established, other work at the observatory will be carried out as conditions permit.

posted 12-03-2020 10:30 AM               

This video, which starts with a view of the top of Tower 4, was taken from the vantage point of an Arecibo Observatory drone, utilized for monitoring the condition of Tower 4 support cables. Four cables are seen in the center of this video. The top cable does not support the telescope platform, but instead supports the catwalk described in the narrative for the previous video.

The three lower cables are, from left to right, M4-1, M4-2, and M4-3. Note that a number of individual wire strands of the M4-1 and M4-2 cables are noticeably broken at the beginning of this video. The M4-3 cable does not appear to have any broken wires at the beginning of this video.

The first indication of the coming failure is the breaking of another M4-2 wire, accompanied by a puff of "smoke" and chips of paint flying away from the surface of the cable. Four seconds later the entire M4-2 cable appears to disintegrate. The failure of M4-2 is followed a fraction of a second later by the demise of M4-1, followed a fraction of a second later by the failure of M4-3.

The drone operator then swings the drone around to view the reflector dish and fallen platform, azimuth arm, Gregorian dome and the falling cables and catwalk. The top section of Tower 12, near the Visitor Center, can be seen tumbling down the hill to the left of the operations building. The Tower 12 backstay cables that connect the top of Tower 12 to the ground cause damage behind Tower 12, well away from the edge of the telescope dish.

posted 10-13-2022 05:09 PM               

NSF to create new education center at Arecibo Observatory

Center to provide educational opportunities and community resources, and foster a strong technical workforce in Puerto Rico

The U.S. National Science Foundation issued a solicitation Oct. 13 for a new multidisciplinary, world-class educational center at the Arecibo Observatory in Puerto Rico that aims to serve as a hub for STEM education and outreach.

The center would expand upon existing education and outreach opportunities currently in place at the Arecibo Observatory site, while also implementing new STEM programs and initiatives. The new center is expected to open in 2023.

The scientific community has expressed broad support for an expanded educational facility. Specifically, the 2020 Decadal Survey for Astronomy and Astrophysics, or Astro2020, recognized that the observatory has, over the course of its nearly 60-year history, become a highly regarded part of the community for many of Puerto Rico's citizens, serving as a source of pride and local economic benefit while also providing access to training and employment for many in the community. Astro2020 called out support for its continuation as an important nexus for education, community, and developing a diversified STEM workforce.

The goals of the center would be to:

• Promote STEM education, learning, and teaching.
  
• Support fundamental and applied STEM and STEM education research.
  
• Broaden participation in STEM.
  
• Build and leverage existing and new collaborations and partnerships.

The center would have four primary functions aligned to its goals:

• Engage the public in STEM through education and outreach activities.
  
• Develop and implement a research and workforce development program.
  
• Support participation of individuals from underrepresented groups in STEM education and research.
  
• Cultivate and build authentic partnerships within and outside of Puerto Rico.

The solicitation calls for proposals to manage the education, STEM research, and outreach aspects of the center. Resources available on site include: a learning center, the Ángel Ramos Science and Visitor's center, exhibition space, laboratory space, auditorium, cafeteria, office space, and dormitories. A third-party contractor will be responsible for maintenance of the site resources listed above, in addition to grounds maintenance.

NSF program directors will work with awardees that have ongoing NSF-funded activities at the Arecibo Observatory to ensure continuity of programs. The solicitation does not include rebuilding the 305-meter telescope or operational support for current scientific infrastructure, such as the 12-meter radio telescope or Lidar facility. Teams seeking to utilize existing scientific infrastructure or proposing for new projects can submit proposals that are complementary to the scope of the new center. All proposals will go through the standard NSF merit review process. Interested parties are advised to contact a NSF program director in their program area to discuss the proposal prior to submission.

This new educational center opportunity is consistent with guidance provided in the "CHIPS and Science Act". The act "encourages the National Science Foundation, in consultation with other Federal agencies, to explore opportunities for strengthening and expanding the role of the Arecibo Observatory in Puerto Rico through education, outreach, and diversity programs, and future research capabilities and technology at the site."