[Music]
Narrator: On the first day of the final month of 2020,
suspension cables forming part of the iconic Arecibo telescope snapped,
releasing an instrument platform as heavy as 2,000 grand pianos.
The thunder of its collapse reverberated across the karst landscape of Puerto Rico.
Even those unfamiliar with the telescope’s name might know it by sight.
The dramatic size of Arecibo—
the largest telescope in the world for more than 50 years—
inspired scenes in movies like Goldeneye and Contact,
burning its image into the public’s consciousness.
For radio astronomers, the telescope was far more than a backdrop;
it was a living tool for science.
Its career began as a U.S. Defense project,
tucked into a sinkhole to shield it from radio interference
as it scanned the ionosphere for missile trails.
In 1969, the National Science Foundation took over Arecibo,
and in 1974, replaced the dish’s wire mesh surface
with 38,000 aluminum panels,
so it could operate at higher frequencies.
One of the telescope’s antenna, called the 430-megahertz line feed,
bounced radar beams off the ionosphere
from its perch on a 900-ton platform,
which hung 137 meters above the dish,
suspended by cables attached to three support towers.
The dish had a spherical shape–unlike the usual parabola–
so Arecibo could view areas of sky not directly overhead.
To “point” at these off-zenith objects,
receivers underneath the platform could be moved using an azimuth arm.
The drawback of the spherical shape
was that it focused incoming rays into a line.
Decades later, engineers installed the Gregorian dome,
which housed additional reflectors to focus rays to a point,
making the telescope more flexible.
The telescope can claim some important discoveries of 20th and 21st century astronomy:
It revealed the first indirect evidence of gravitational waves;
mapped Venus’s cloud-veiled surface;
and detected the first planets outside our Solar System.
The telescope also bounced radio waves off planets and asteroids;
heated plasma in the Earth’s atmosphere to create artificial auroras;
and beamed a message to the stars.
[Sound: Arecibo transmission to M13]
But as its achievements mounted,
age began to creep up on Arecibo.
A moist tropical climate, hurricanes,
and earthquakes all took a toll.
In the 1970s, to combat water seeping into the cables and causing corrosion,
caretakers painted the cables and
installed air pumps to keep them dry.
The Gregorian dome also added weight to the structure,
so engineers had to tack on auxiliary cables
to support the instrument platform.
One of these cables was the first to fail
leading up to the collapse.
It’s possible Arecibo didn’t receive all the care it needed in recent years.
As the National Science Foundation turned its attention
to newer astronomy projects,
it reduced its funding for the aging telescope.
A panel of experts has proposed
building a new, more capable telescope in Arecibo’s stead,
but its $400M price tag may meet roadblocks.
Wanda Vázquez Garced [translated from Spanish]:
It is a pleasure for me
to have signed this executive order today
so that we can see our wish come true
that we once again have the Arecibo radio telescope
in better condition and with all the scientific advances.
If funded, an expansive telescope project
would provide a boost for Puerto Rico,
which has reeled in the wake of several natural disasters,
including 2017’s Hurricane Maria.
A new scope might also steer the next generation of astronomers,
both in the tropics and round the globe,
toward another half-century of profound discovery.
[Music]