For decades, the words “Arecibo Observatory‘was a shorthand for the facility’s massive radio telescope, one of the rare tools to achieve iconic status outside its core science community.
But cable failures shattered the telescope and much of the expanded dish last year, forcing the observatory to take stock of the science it can still do without the iconic telescope. In the months since the Puerto Rican telescopeAfter the fall, scientists at the site gathered to look ahead to the immediate future of research at the site, using the tools that remain.
“Our focus has really shifted to a lot of this other equipment,” Francisco Córdova, director of Arecibo Observatory, told Space.com. “Everyone was in operation throughout. They were certainly not the highlight of the site, but did work.”
Related: If the Arecibo Observatory were lost, scientists would create a hole that could not be filled
Unusually flexible scientific thinking has always been one of Arecibo’s strengths. Although the massive radio dish was originally designed for atmospheric scientists to study the ionosphere, the facility flourished to play a key role in two other scientific communities as well: radio astronomy and planetary science.
That history means that Arecibo Observatory is used to offers a variety of research – even if the radio telescope provided the spotlight – and prepared the observatory to manage an eclectic research portfolio.
Arecibo and beyond
On the main campus of Arecibo Observatory, located in the mountainous lush vegetation of Puerto Rico, scientists are gathering the remaining tools to continue Arecibo’s scientific legacy. Although the massive radio telescope dominated the site, it was hardly the only equipment that had built up over the decades long history of the observatory.
One of the other instruments available is a 12 meter long radio antenna. It was originally brought to the site to simplify the work of the main telescope on very long base interferometry, which otherwise required complicated steering maneuvers of massive equipment.
“Now that it’s going to be our most important instrument for astronomy for a while, we’re shifting the priorities there,” Córdova said. First, on the agenda for the smaller dish, which is on a hill overlooking the main telescope, it should only join existing interferometry networks with a very long base, as such cooperation increases the power of individual instruments. Observers are also hoping to add a cryogenic cooling system to the antenna so that the smaller telescope can do more meaningful research.
There are also two member systems, or light detection and switching systems, available on the main area of Arecibo. Such systems bounce off lasers (in this case) the atmosphere to better understand its ingredients and structure. One is restored as the observatory continues hurricane recovery Maria, which plagued Puerto Rico in September 2017, but Córdova estimates that it would work normally by the end of this year.
The ionospheric heating systems of the plant are in a more difficult state. Atmospheric scientists use such systems during week-long experiments that locally change the top layer Earth’s atmosphere. Such systems, for example, can create so-called “artificial auroras” that look, but are much fainter, than the light rays created by charged particles that strike molecules in the upper atmosphere. Scientists who study how the atmosphere naturally responds to such events, which can affect navigation and communications satellites, find experiments a useful complementary approach.
“It’s very unique equipment,” Córdova said. “They’ve been around for a while, but it’s always been a science that is a niche. It’s very unique and it’s not quite understood yet, so there are a lot of opportunities.”
The systems depend on antennas housed in the center of the massive radio dish; out of six antennas offered by the observatory, there are three more. The one, however, caused damage, and the remaining antennas were a maladaptive set. Once the antennas are secure to access, the observatory must move, repair and repair them.
“We feel it is an ability that we can recover fairly quickly,” Córdova said, noting that the exact timeline depends on how quickly staff can remove debris from the crash. In addition, the system previously worked with a device called an incoherent distribution radar, which was housed on the hanging platform above the radio dish and was destroyed during the crash and which the observatory could not fully mimic.
The observatory will also need to find a structure that will fulfill the role of reflector instead of the massive radio dish. “We are currently exploring different alternatives for what the right approach would be,” Córdova said. “We’re trying to get a little creative with that aspect.”
Related: Puerto Rican scientists mourn the loss of the iconic telescope of Arecibo Observatory
But the projects least affected by the collapse of the radio telescope are projects not located near the now-destroyed dish. These include those known as the Remote Optical Facility, a fairly new facility on the small island of Culebra, which is about 17 mi (17 miles) east of Puerto Rico.
At the moment, the main equipment there is an airspace camera that, along with another located on the main observation site, watches all day what is happening overhead, which is unusual, Córdova said. “Our astronomical observations are typically very pointed,” he said. “This equipment is therefore very interesting in the sense that it gives you the ability to make 24/7 type observations.”
One phenomenon that airspace cameras can spot is meteors penetrating the Earth’s atmosphere, and Arecibo plans to have a second instrument at the Culebra site to study such objects as well, this one a meteor radar system, a partnership with the University of Illinois. The arrival of the equipment comes from Chile to the site, a journey delayed by restrictions set to delay the equipment coronavirus pandemic, but the observatory hopes to set up the meteor radar system later this year.
Radar is a well-known area for the Arecibo Observatory; the radio telescope’s planetary radar system was the most powerful in the world. But the system is no more, and the meteor radar system will be completely different, Córdova stressed. “[It’s] nowhere near our old planetary radar, but it does not have to be, because the idea is that we study meteors as they enter the earth’s atmosphere, but we do not want to go beyond that.
Before the collapse of the radio telescope, there was also a second instrument that would join Culebra, a member to study aerosols in the atmosphere, especially the Substance of the Sahara which blows from Africa across the Atlantic Ocean and can wash over the island. The new instrument can determine how high the dust and other aerosols are in the atmosphere, a relatively difficult measurement to make. “There is very little equipment that can be used to study it,” Córdova said.
Turn the clock back
And then, of course, there is the task of managing the rich legacy of decades of observations through the lost radio telescope itself. First, the observatory is working on completing a project to gather Arecibo data from the various locations where it is held to compile one complete archive stored in the digital cloud, Córdova said. The project should be completed within a few months, he added.
Then scientists work with software engineers to develop automated algorithms to search old data, looking for phenomena that were completely unknown when the telescope started working but are now commonplace.
“We have had many recent discoveries that we did not know about 20 to 30 years ago, such as FRBs and exoplanets,” Córdova said, referring to the mysterious fast radio bars which has astonished astronomers for more than a decade.
“Is there a possibility that many of the discoveries in Arecibo were hidden in older datasets? Could someone have picked up an FRB in the ’70s or’ 80s or an exoplanet in the ’70s or’ 80s? did not know, because they never really had the computing power? ‘
The observatory team also hopes that the algorithm work will eventually apply to another of the telescope’s previous activities, studying the shape of asteroids near Earth. Although scientists can work directly with the observations, one important product of planetary radar is a so-called shape model that sharpens their understanding of the exact shape of an object.
There is only one problem: producing a mold model takes at least six months, sometimes up to a year, far too long to keep up with Arecibo’s lost planetary radar system. “In a given year, we would see 100 different near-Earth objects with our planetary radar. If you can only map two of them, it will take you a while,” Córdova said.
But for now, the team is working on the algorithm to detect fast radio bursts. Arecibo Telescope conducted its final survey for rapid radio bursts in March 2020, Córdova said, and it takes about nine months to examine observatory scientists by going through all the data the survey collected. So the hope is that an algorithm will speed it up – perhaps so important that scientists can gather follow-up observations guided by interesting data.
Then it’s time to do the same exoplanet. About how much such alien worlds could hide in old Arecibo data, Córdova said there is no way to know.
“We really have no idea, and that’s one of the very cool things that everyone is a little bit excited about,” he said. “There could be hundreds of these things we didn’t know all along, or maybe it’s one or two we don’t know.”
Email Meghan Bartels at [email protected] or follow her on Twitter @meghanbartels. Follow us on Twitter @Spacedotcom and on Facebook.