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Few telescopes will receive an emotional response from the general public when it is finally announced that they will be deactivated. In the case of the Arecibo Observatory in Arecibo, Puerto Rico, in recent months not only astronomers but also countless people around the world have waited with bated breath after the first reports of damage to the giant radio telescope dish.
When the National Science Foundation announced that it would disable the telescope, there was an understandable display of pain and shock. Not only is Arecibo a landmark in Puerto Rico, it’s the telescope of iconic films like Golden Eye (1995) and Contact (1997). Its data has fueled public programs such as the Seti @ Home and Einstein @ Home projects.
Was the disappearance of Arecibo really inevitable and what does it mean for the scientific community?
What defines Arecibo
The real question is: what have we lost? Are there any successors to Arecibo who are able to fill the huge gap that the scientific community now faces? Looking at the aspects of the telescope that made it unique helps us find those answers.
Telescopes are essentially highly sensitive instruments for observing remote sources of electromagnetic radiation. In the case of optical telescopes, this means the visible part of the EM spectrum. Radio telescopes work similarly but are tuned to receive radio frequencies. Arecibo was able to acquire between 1-10 GHz with multiple receivers using 221 effective meters of its 304 meter diameter. Just as the primary mirror of an optical telescope largely determines the amount of light that will eventually reach the sensor, so do the size and shape of a radio telescope’s primary (flat) mirror.
Most telescopes can be adjusted to point the reflector at different parts of the sky. This is primarily a question of what mechanics and engineering allow, with the Green Bank Telescope in West Virginia currently the largest fully steerable radio telescope with a diameter of 100 meters. Puerto Rico’s Arecibo radio telescope and Chinese FAST radio telescope have fixed reflectors that exploit the natural depressions in the ground left by a karst sinkhole. Within this bowl-shaped depression the elements that make up the dish are installed, largely following those contours, with a mobile receiver array to aim the telescope. While convenient, this limits the view of these telescopes to a fairly narrow part of the sky.
Both newer and physically larger, it would seem obvious that the Chinese FAST telescope is superior to Arecibo, this is not entirely true. Arecibo’s parabolic reflectors are mounted more rigidly than those of FAST. While the latter is more flexible with winches capable of adjusting the shape of the reflector net, this one comes with trade-offs at these higher frequencies. Even with updates to FAST receivers similar to the updates Arecibo received in 1997, FAST would only be able to cover frequencies up to around 5 GHz, only half the performance of Arecibo.
In addition to these properties, there is also the issue of radar astronomy, which requires the transmission of powerful radar signals. Arecibo has four radar transmitters, 20 TW (continuous), 2.5 TW (pulsed), 300 MW and 6 MW. These take up a significant amount of space and therefore cannot be mounted on FAST’s secondary platform together with its receivers due to weight and space issues. Arecibo is just one of two telescopes that have seen regular use in radar astronomy, the other being the 70-meter Goldstone Solar System Radar, with a 500 kW transmitter.
As asteroid and comet detection is an essential part of Arecibo’s radar astronomy tasks (tracking and early warning system), this has left a major blind spot. Without Arecibo, we have to rely primarily on optical telescopes to track these objects as they traverse the solar system.
The Infrastructure Budget Dance
Perhaps unsurprisingly, Arecibo is a Cold War artifact, envisioned as part of an anti-ballistic missile (ABM) shield. Installations like Arecibo would provide detection tasks, presumably being sensitive enough to filter true warheads from fake ones inside a MIRV ICBM by their radar signature. Without a solid understanding of the exact physics of a re-entering ICBM, Arecibo was part of an ARPA-led effort to fill the knowledge gaps here.
As the Cold War dragged on and priorities shifted before the Soviet Union finally dissolved, Arecibo saw itself in a situation not unlike the rust and peeling paint wonders of the Soviet Union. Unnecessary as a military asset, it has seen its operating budget shrink from year to year. Even with asteroid research as one of its unique mission profiles, NASA announced in 2001 that it would cut funding by 27% and “encourage” the National Science Foundation (NSF) to fund the $ 11 million budget of the. ‘entire program.
In 2007, the NSF announced that due to its budget reduction, it would have to close Arecibo unless other sources of funding could be found. Interestingly, Puerto Rico itself is quite poor, with its government not having the financial means to support even such an iconic telescope, and no senators in Washington DC lobbying on its behalf due to Puerto Rico not is a state of the United States.
NASA funding for the telescope was restored in 2010, with an increase in 2012 to $ 3.5 million per year. Despite this, the NSF made changes to the way the Arecibo Observatory was run during this time, seeking business and other partners and removing Cornell University from the project. By 2015, NSF was reporting that it was considering decommissioning the plant.
When Hurricane Maria damaged the 430 MHz power line and part of the primary dish in 2017, a consortium led by the University of Central Florida (UCF) managed to prevent the observatory from being dismantled through financial support, but then On August 10, 2020, one of the secondary platform support cables broke, damaging the primary dish and the receiver platform.
As decades of limping with minimal operating budget reached reality, November 7 saw a second cable break, further damaging the primary dish. After engineers examined the facility following this second incident, the press statement states that:
Preliminary analysis indicates that the main cable, which failed on November 6, should have easily handled the additional load based on design capacity. Engineers suspect the second cable is likely to have failed because it has degraded over time and has carried an additional load since August.
All this seems to indicate the lack of a maintenance budget which has led to the situation where the numerous cables of the Arecibo Observatory have not been regularly inspected, maintained or replaced. Especially in a fairly humid and hot climate such as Puerto Rico where corrosion of steel cables would accelerate, a lack of maintenance would cause reductions in load capacity.
What could have been
A big problem with science installations like Arecibo is that they aren’t flashy or attractive enough to warrant a steady stream of funding, with some administrations worse than others. The main reason is that a lot of science mostly involves waiting, digging into years of data, more waiting, and crunching more numbers and running models in the hope that a confirmed theorem will be seen.
When a politician or average person on the street is asked what their thoughts are on Arecibo’s disappearance, it is unlikely that many can summarize what the facility was used for and why its loss is felt far beyond the astronomy community. .
The Visitor Center of the Ángel Ramos Foundation, located near the observatory, was opened in 1997. It serves as an educational center with exhibits and displays not only on the Arecibo Observatory, but also on astronomy and atmospheric sciences. With the loss of the observatory, the future of this center and Puerto Rico’s role in astronomy is put into question.
For the future
In a world where some people count their value in the billions and Wall Street progresses in the trillions, the operating and maintenance budget for a facility like Arecibo is microscopically small. Despite this, there seems to be no indication that the decision to deactivate Arecibo will be reversed. At this point, whether or not a replacement facility will be built in Puerto Rico or anywhere else in the United States is still pending.
All we know for sure right now is that despite its different geographic location and lack of radar transmission capability, the FAST telescope along with a number of smaller radio telescopes will be able to detect most of the game. Due to China’s treatment of large science projects as a sign of prestige, in addition to building FAST, the country’s fully steerable 110-meter Qitai radio telescope is also slated to go online in 2023, which would make it the largest in the world. its kind in the world.
One can only hope that the United States and others will take the bait and enter into friendly competition with China to build the best and most useful telescopes and other science projects to further reach humanity’s stars. Because in the end, having only crumbling sites like Arecibo to show for your economic prowess isn’t worth it at all when that one large asteroid manages to avoid Earth.
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