The Arecibo Big Dish has reached the end of the line

The Arecibo Big Dish has reached the end of the line
Zoom in / An aerial view of the Arecibo facility, showing the increasingly fragile cables supporting the instrument platform, as well as the wound caused by the failure of one of these cables.

The National Science Foundation today announced the closure of its popular Arecibo radio observatory. The main dish of the observatory is built on top of a hill in Puerto Rico, and is more than 300 meters wide. Feature in popular culture From James Bond movies to video games. But despite its long history of scientific contributions, the observatory has struggled for funding for more than a decade, and the two cables supporting it have failed this year, leaving it in an unstable state.

After engineering studies determined that there was no way to repair the devices without putting workers at risk, NSF made the decision to close the observatory.

More than a large dish

While the sheer size of the Arecibo main course captured the most attention, the dish was merely a reflector. The end of the telescope’s actual work, sensing radio waves, was an instrument platform suspended above it by cables suspended from three towers. The device’s platform contains a receiver that can be moved to various locations above the disk, giving it the ability to resolve signals from more directions than a stationary plate might suggest.

Since its inception in the 1960s, the observatory has played a role in many discoveries, particularly in the field of pulsars, a class of radio-emitting neutron stars. She has also participated in SETI searches, submitting a photo to a star group on the assumption that any smart life out there might participate in her SETI program. But over the past 15 years or so, the National Salvation Front, Arecibo’s main support, cut its funding to the observatory, which has struggled to maintain its full operations during this period.

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But it wasn’t money that ultimately wiped Arecibo; Instead, it was the tools platform. In August of this year, one of the auxiliary cables that help support the platform was cut off, causing a wound to the reflective plate of the radio below. While making plans to replace this cable and fix the plate – replacement cables were already in order – one of the 7.5cm main cables was cut onto the same tower on November 6.

A later engineering analysis determined that this cable failure occurred despite the fact that the stress on it was only about 60 percent of what should be the minimum breaking strength. This raised serious questions about the stability of the remaining cables, and thus the chassis’s ability to support its hardware platform. The analysis concluded that it is not safe to know; The platform can collapse without warning, and any severed cables will pose a risk to any operator in the towers, as large cables will move at very high speeds after a break. Of three additional engineering firms that NSF and University of Central Florida consulted, two agreed with this assessment.

“Until these assessments came, our question was not whether or not the observatory should be reformed but how,” said NSF’s Ralph Gaum. “But in the end, the abundance of data showed that we simply could not do it safely. This is a line that we cannot cross.”

The end is near

For now, NSF is simply announcing that it will begin planning the decommissioning process. Work was already underway to move data archives from the device to the cloud, and it is clear that plans to safely remove the platform will involve lots of additional engineering analyzes. The NSF said many other science programs associated with the site will remain open. The observatory also functions as a major center of communication between the scientific community and the Puerto Rican community – understanding how to maintain this dynamic in the absence of an active tool will also require further study.

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It’s hard to argue with the risk analysis. And it’s not hard to imagine that more modern and flexible tools can accomplish the science we expect from Arecibo at a lower cost, which explains why Arecibo has struggled with funding for over a decade. Given these two factors, it is clear that the time for Arecibo has come.

But it’s still hard to accept losing a code like this.

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