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Few telescopes will receive an emotional response from the general public when it is finally announced that they will be decommissioned. In the case of the Arecibo Observatory in Arecibo, Puerto Rico, the past few months have seen not only astronomers, but also countless people around the world anxiously awaiting after the first reports of damage to the gigantic antenna. radio telescope.
When the National Science Foundation announced it was going to decommission the telescope, there was an understandable wave of grief and shock. Arecibo is not just a landmark in Puerto Rico, it is the telescope of iconic films such as Golden eye (1995) and Contact (1997). Its data fed into public programs such as the Seti @ Home and Einstein @ Home projects.
Was Arecibo’s demise really inevitable and what does this mean for the scientific community?
What defines Arecibo
The real question is: what have we lost? Are there Arecibo successors capable of filling the very great void facing the scientific community? Examining the aspects of the telescope that made it unique helps us find these answers.
Telescopes are essentially very sensitive instruments for observing distant sources of electromagnetic radiation. In the case of optical telescopes, this means the visible part of the EM spectrum. Radio telescopes work the same way but are tuned to receive radio frequencies. Arecibo was able to capture between 1 and 10 GHz with multiple receivers using 221 effective meters of its diameter of 304 meters. Just as how the primary mirror of an optical telescope largely determines how much light will ultimately reach the sensor, so does the size and shape of a radio telescope’s primary mirror (dish).
Most telescopes can be adjusted to point the reflector at different parts of the sky. It’s mostly a question of what the mechanics and engineering allow, with the Green Bank Telescope in West Virginia currently the largest fully steerable radio telescope with a dish diameter of 100 meters. Puerto Rico’s Arecibo and China’s FAST Radio Telescope have fixed reflectors that use natural depressions in the terrain left by a karst chasm. In this bowl-shaped depression, the elements that make up the parabola are installed, largely following these contours, with a mobile receiving network to aim the telescope. While convenient, this limits the view from 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 in place more rigidly than those of FAST. While the latter is more flexible with winches capable of adjusting the shape of the reflector mesh, this comes with tradeoffs at these higher frequencies. Even with upgrades to FAST receivers similar to the upgrades Arecibo received in 1997, FAST could only cover frequencies up to around 5 GHz, which is only half of Arecibo’s performance.
In addition to these properties, there is also the question of radar astronomy, which requires the transmission of powerful radar signals. Arecibo has four radar transmitters, of 20 TW (continuous), 2.5 TW (pulsed), 300 MW and 6 MW. These take up a lot of space and therefore cannot be mounted on FAST’s secondary platform alongside its receivers due to weight and space issues. Arecibo is just one of two telescopes that have been used regularly in radar astronomy, the other being the 70-meter Goldstone Solar System Radar, with a 500 kW transmitter.
With the detection of asteroids and comets being an essential part of Arecibo’s radar astronomy tasks (tracking and early warning system), this left a major blind spot. Without Arecibo, we mainly have to rely on optical telescopes to track these objects as they pass through the solar system.
The infrastructure budget dance
It is perhaps not surprising that the Arecibo is a Cold War artifact, envisioned as part of an anti-ballistic missile (ABM) shield. Facilities like Arecibo would provide detection functions, presumably being sensitive enough to filter out real warheads from fake warheads in an ICBM MIRV from their radar signature. Without a solid understanding of the exact physics of a re-entrant 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 final dissolution of the Soviet Union, Arecibo found itself placed in a situation similar to that of the rusty and peeling paint marvels of the Soviet Union. Useless as a military asset, it has seen its operational budget reduced year after year. Even with asteroid research as one of its unique mission profiles, NASA announced in 2001 that it would cut funding by 27% and “ encouraged ” the National Science Foundation (NSF) to fund the budget. $ 11 million from the entire program.
In 2007, the NSF announced that due to its own budget cut, it would have to shut down Arecibo unless other sources of funding could be found. It should be noted here that Puerto Rico itself is rather poor, with its government lacking the financial means to support even such an iconic telescope, and no senator in Washington DC to lobby on its behalf because Puerto Rico does not. is not a US state.
NASA funding for the telescope was reinstated in 2010, increasing in 2012 to $ 3.5 million / year. Despite this, the NSF changed the way the Arecibo Observatory was run during this time, seeking out business and other partners and removing Cornell University from the project. In 2015, the NSF reported that it was considering decommissioning the facility.
When Hurricane Maria damaged the 430 MHz power line and part of the main antenna in 2017, a consortium led by the University of Central Florida (UCF) managed to prevent dismantling of the observatory thanks to financial support, but on August 10, 2020, one of the secondary platform support cables broke, damaging the main dish and the receiver platform.
As decades of limping on a minimal operating budget caught up with reality, November 7 saw a second cable break, further damaging the main antenna. After engineers reviewed the facility following this second crash, the press statement said:
Preliminary analysis indicates that the main cable, which failed on November 6, should have easily handled the extra load depending on design capacity. Engineers suspect that it is likely that the second cable failed because it has degraded over time and has been carrying additional load since August.
All this seems to indicate the lack of maintenance budget leading to a situation where the numerous cables of the Arecibo Observatory were not regularly inspected, maintained or replaced. Especially in a fairly humid and hot climate like that of Puerto Rico where corrosion of the steel cables would be accelerated, a lack of maintenance would have led to reductions in load capacity.
What could have been
A major problem with science facilities like Arecibo is that they aren’t flashy or cool enough to warrant a constant flow of funding, with some administrations being worse than others. The main reason is that a lot of science mainly involves waiting, digging through years of data, more waiting and more calculations, and running models in the hope of seeing a theorem confirmed.
When you ask a politician or the average person on the street what they think of Arecibo’s disappearance, it’s unlikely that many can sum up what the facility was for and why his loss is felt far beyond it. of the astronomical community.
The Ángel Ramos Foundation Visitor Center located near the observatory was opened in 1997. It serves as an educational center with exhibits and exhibits 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 are strongly questioned.
For the future
In a world where some people count their worth in billions and where Wall Street marks its progress in the trillions, the operating and maintenance budget for a facility like Arecibo is microscopically small. Despite this, there is no indication that the decision to downgrade Arecibo will be overturned. Whether a replacement facility will be built in Puerto Rico or elsewhere in the United States is still open at this point.
All we know for sure at the moment is that despite its different geographic location and lack of radar transmission capability, the FAST telescope along with a host of smaller radio telescopes will be able to take the major part of the slack. Due to China’s treatment of large science projects as a sign of prestige, in addition to building FAST, they are also expected to bring the country’s 110-meter fully steerable Qitai radio telescope online in 2023, which would make it the largest in the world. kind in the country. world.
One can only hope that the United States and others will take the bait and enter into a friendly competition with China on the construction of the best telescopes and other most useful science projects to advance humanity to the stars. . Because in the end, having only crumbling sites like Arecibo to show off its economic prowess isn’t worth much when this big asteroid manages to not avoid Earth.
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