The 305-meter telescope at Puerto Rico’s Arecibo Observatory has survived decades of hurricanes, including Hurricane Maria in 2017, and earthquakes, including unusually strong ones in early January 2020. It has also survived the trials of its owner, the National Foundation. for Science in the US, to reduce its funding. But in the early morning of December 1, 2020, its 900-ton suspended instrument platform collapsed, destroying the 57-year-old telescope.
Arecibo has contributed to many significant discoveries, including observations of Nobel Prize-winning pulsars and the first confirmed exoplanets. Closer to home, the observatory’s radar equipment emitted radio signals to identify the shape, rotation and speed of asteroids potentially dangerous to NASA. The telescope also monitored dwarf stars, planets in our solar system, and disturbances in the Earth’s atmosphere.
The fall of Arecibo was a blow to what was already a year of losses. The pandemic has forced my interactions with online students and colleagues and worries me about my family’s health: my octogenarian parents, as well as my wife, a nurse who lost a friend and colleague to COVID- 19. In such times, it can be a comfort to remember the beginnings.
I was 12 years old when I first visited the Arecibo Observatory. In 1981, visits were scheduled and I called from a pay phone to try to make a reservation. Garred ‘Gerry’ Giles, the head of the observatory’s scientific services, answered the phone in broken Spanish and gave me a day and an hour. My parents agreed to go for two hours. We all knew my enthusiasm for astronomy, but I don’t think anyone predicted that I would be a physicist and astrobiologist at the University of Puerto Rico in Arecibo.
Gerry showed us the control room of the observatory, where a large window overlooked the massive suspended platform, a rotating structure that held the receivers in which the radio signals reflected by the antenna below came into focus. In that year, the observer’s measurements were used to create the first radar maps of Venus’ surface: the planet’s thick clouds had prevented optical observations, but Arecibo’s strong radio signals could pass and return. I still have the printed photos of Venus that Gerry gave me that day.
My parents and I got under the boat, riding in a Jeep on a dirt road. From a distance, the vessel looked like a solid shell, but it was made of many mesh-like plates through which light reached the ground. The area was humid, calm and lush with vegetation. The ship was far above us, and the suspended platform visible even higher, through the net.
Decades later, I gave my first scientific lecture at the observatory as a visiting scientist. My research is about the habitability of the planets, understanding the conditions necessary for any life, from microbial to intelligent. A week before I arrived, I looked for Gerry in an old telephone directory, unsure if he was still in Puerto Rico. I told him that more than 25 years ago, he gave a child a wonderful experience and told him the date and time of my presentation. He had retired by then, but he came – and I was delighted.
More telescopes means more observations, confirmations and discoveries. Most radio telescopes, such as the world’s largest five-hundred-meter spherical telescope (FAST) in China, were designed only to receive signals, but Arecibo’s 305-meter antenna was both capable of receiving, as well as to transmit. The best tool to listen and talk to the Universe is now silent.
The last time Arecibo was used for a targeted search for signs of extraterrestrial technology, called technosignatures, was from 1998 to 2004, as part of the privately funded Phoenix project, led by the SETI Institute in Mountain View, California. The project noticed 800 stars nearby, but did not transmit transmissions. In 2019, NASA re-established funding for exoplanet and exobiology research to search for technosignatures.
No such project took place at the observatory when it collapsed, but I had decided to change that. My research students had planned to observe stellar systems with potentially habitable planets for longer than anyone else, and thus increase sensitivity to weak signals. We made our last observations of a red dwarf star in early August 2020, just four days before the first of the two cable failures shut down the observatory. Shortly afterwards, we became one of dozens of scientists – cosmologists, stellar physicists, atmospheric scientists – who met weekly to come up with ideas on how to save and improve the telescope. I did not give up after the December collapse; we intend to find support to rebuild Arecibo with a new, better telescope.
As a child, I learned from Gerry how a telescope, a moment, a person, can affect your life. It took me years of hard work to learn to use the Arecibo Observatory and it was hard for me to see how it went in less than a minute. Generations of Puerto Rican scientists are also saddened.
Although I record most of my observations electronically, I like to keep a notebook when I’m physically with the instruments. January 2020 was the time to start a new one, but with earthquakes, pandemics and remote work, we did not make a single entry. I’m going to start writing again in 2021 – although I will never regain that missing year, one in which we all lost so much.