A view of the Arecibo Observatory, which is to be decommissioned after a second cable break. (Arecibo Observatory/ U.S. National Science Foundation)
Arecibo’s end and Canada’s bright radio future

This biweekly column focuses on a trending news topic in Canadian astronomy. This week: as Arecibo sees last light, Canadian projects could help pick up the scientific slack.

The nearly 60-year-old Arecibo telescope has collapsed after hurricane damage and cable problems sidelined the observatory permanently. It is a loss to the scientific community around the world — but a new Canadian telescope array under consideration could take on some of the work.

On November 19, the United States National Science Foundation announced that the venerable radio telescope would need to cease its multi-decade mission of probing the universe in radar, doing everything from looking for alien signals under the SETI program to scanning near-Earth asteroids to learn their shape and size. A press release states that the engineering firm that assessed the structure found repair work on the telescope could lead to another cable failure and the structure’s collapse. The telescope collapsed Tuesday, December 1, resulting in damage to the dish and surrounding facilities. No injuries were reported.

A view of the Arecibo Observatory, which is to be decommissioned after a second cable break. (Arecibo Observatory/ U.S. National Science Foundation)

Canadian astronomers are among those mourning the observatory’s loss. In 2018, for example, a University of Toronto-led team used Arecibo to ferret out then-unprecedented detail in a pulsar located roughly 6,500 light-years from Earth. Despite its age, Arecibo was so sensitive that — along with using a lucky alignment of cosmic objects — the observation was equivalent to using a telescope on Earth to see a flea on the surface of Pluto, according to a press release from the Dunlap Institute for Astronomy and Astrophysics. The study charted the movement of gas to better understand the environment around these strange objects.

This Canadian-led research project was just one of many from teams worldwide that Arecibo supported, to push forward the science of pulsars — dense, rapidly spinning neutron stars first observed in 1967.

“It [Arecibo] detected the first double neutron star binary system and observed the first indirect evidence of the existence of gravitational waves, which led to the 1993 Nobel Prize in physics,” said pulsar astronomer Cherry Ng, a researcher at U of T’s Dunlap Institute not involved in the 2018 pulsar study.

Ng is also involved in fast radio burst (FRB) astronomy, the study of transient radio bursts in the cosmos from some astronomical object or objects.

“Arecibo has also discovered the first repeating fast radio burst,” she added. “These are just some of the ‘first’ astronomical breakthroughs Arecibo has given us. The legacy of Arecibo will surely be missed.”

Ng is also a member of the North American Nanohertz Observatory for Gravitational Waves (NANOGrav) collaboration, which aims to directly detect low-frequency gravitational waves using pulsars. Arecibo was one of the two main telescopes that provided regular pulsar observations to the collaboration, she noted.

“The Arecibo data set is extremely valuable, both because of the unparalleled sensitivity of Arecibo and because of the 15-plus years of consistency,” she said. “Arecibo provided some of the highest precision pulsar observations we have ever had.”

Canadian observing projects

Fortunately for Canadians, there is another radio observatory available that saw first light in 2017 — and an even more advanced telescope array on the drawing board.

Located south of Penticton, the CHIME (Canadian Hydrogen Intensity Mapping Experiment) radio telescope at the Dominion Radio Astrophysical Observatory in British Columbia links four individual receivers together through a process called interferometry.

“CHIME is proving itself to be an amazing pulsar instrument. It is observing of the order of 500 pulsars per day,” Ng said. While CHIME — which commenced science operations in 2018 — is less sensitive than Arecibo, it can observe individual pulsars more frequently, allowing astronomers a better sense of how these objects evolve over time.

An even more powerful upgraded telescope called CHORD (Canadian Hydrogen Observatory and Radio-transient Detector) could come to Canada in the future, Ng pointed out. This “pan-Canadian” project is supposed to build on the success of CHIME, but use a central array of 512 six-metre dishes and a pair of distant stations, each of these stations including cylinders and a 64-dish array.

“CHORD will measure the distribution of matter over a huge swath of the universe, detect and localize tens of thousands of fast radio bursts (FRBs), and undertake cutting-edge measurements of fundamental physics,” according to a white paper of the telescope’s capabilities uploaded in 2019 to the scientific prepublishing site Arxiv.

Earlier this year, the Canadian Astronomical Society held a consultation concerning our country’s long-range plans for astronomy and astrophysics, which helps the community determine priorities in asking for funds for ambitious projects. In a report released in September, CHORD was the recommended top priority for new mid-scale investments in future facilities, with an estimated construction cost of $23 million.

The CHORD consortium (which includes the University of Toronto) recently sent a proposal to the Canada Foundation for Innovation requesting a grant to support construction at Dominion, money that would be added to other seed funding and in-kind funding that is already allocated to the project. The current estimated timeline calls for completion of construction in 2023, subject to considerations such as finding appropriate land in consultation with Indigenous communities.

“I am excited that the innovative designs of these telescopes will open up a new window in pulsar astronomy,” Ng said, since CHIME has higher revisit rates of pulsars and the proposed CHORD allows for wide frequency observations of FRBs and pulsars. But the loss of Arecibo will be acutely felt in the astronomy community, no matter the worthiness of its successors.

Elizabeth Howell (Ph.D.) is a Canadian space journalist who has been obsessed with the topic ever since she, as a young teenager, saw the movie Apollo 13 in 1996. She grew up wanting to be an astronaut. While that hasn’t happened (yet), Elizabeth has seen five human spaceflight launches — including two from Kazakhstan — and she participated in a simulated Red Planet mission at the Mars Society’s Mars Desert Research Station in Utah.

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