The living quarters may be as spare as a college dorm room, and the nightlife is all work and little play. But when it comes to astronomy and awe, the Arecibo Observatory delivers big-time. Imagine a space station, hanging by cables 45 stories above a quarter-mile-wide lakebed of aluminum, and you get an idea of the awe. Imagine a 3-D map of the Milky Way, charted by means of radio waves, and you get an idea of the astronomy.
2003 marks the 40th anniversary of the observatory, the biggest single radio dish in the world. But rather than settling into middle age, the telescope is getting a $1 million makeover to open its window on the radio universe seven times wider.
The project calls for adding six more radio receivers to the current one at the observatory, creating a seven-feed system known as the Arecibo L-band Feed Array, or ALFA. Funded by the National Science Foundation and due for completion in 2004, the ALFA project would allow Arecibo to conduct large-scale sky surveys with unprecedented sensitivity. The receivers could also be tuned to monitor different frequencies simultaneously.
Such an instrument could produce dynamic 3-D maps of the distribution of hydrogen in the Milky Way galaxy and beyond — giving astronomers a better sense of the interstellar sea that bathes the stars. Those maps, in turn, could be processed to create a virtual “space flight through the galaxy,” said Chris Salter, who heads Arecibo’s radio astronomy group.
Other upgrades would let astronomers actively probe the ionosphere, a zone of the upper atmosphere that holds the key to many of Earth’s electromagnetic mysteries, and allow for faster processing of Arecibo’s ever-increasing stream of data.
Then there’s the search for extraterrestrial intelligence — the endeavor that made Arecibo famous. Arecibo’s telescope is currently used for the SETI Institute’s targeted search as well as Project Serendip’s full-sky SETI survey. Serendip provides the raw data for SETI@home, the world’s biggest distributed computing project with more than 4.5 million registered users. The telescope dish was also the site of the first intentional radio transmission to extraterrestrials, back in 1974.
“You can talk about pulsars and black holes and the ionosphere, but really the question that always comes up is, ‘What about the extraterrestrials?’” Daniel Altschuler, the observatory's director, acknowledged.
The view up close
If E.T. ever were to pay a visit to Arecibo, even the aliens might be impressed. It’s hard to convey in words, pictures or even movies (such as the James Bond thriller “Goldeneye” or the science-fiction saga “Contact”) just how big the 1,000-foot-wide (305-meter-wide) dish looks from up close.
Here’s a shot at some comparisons: The dish has as much area as the lake at New York’s Central Park (18 acres). The reflected radio signals are collected by instruments on a triangular platform that hangs 45 stories above the dish, which at 700 tons weighs more than the international space station ever will. That platform is suspended from three reinforced concrete towers that rise higher than the towers on the Brooklyn Bridge (365 feet above the ground vs. 276 feet above the water).
It’s one thing to spout the facility’s dimensions, but quite another to ride a cable car the size of a bathroom stall up 450 feet (137 meters) to the platform.
“Are you afraid of heights?” operations technician Wilfredo Portalatin asked in advance of the ride. Tony Acevedo, the head of Arecibo’s scientific services, said that question gets asked regularly because one visitor suffered a panic attack during the ride up.
At the top, you can look down from — and through — the grates of a catwalk at the aluminum dish below, or at the jungle hills around the observatory grounds. The site was selected in the late 1950s because of its location in Puerto Rico’s mountainous karst region, with a sinkhole serving as a natural foundation for the spherical reflector. Originally conceived primarily as a radar instrument for studying the ionosphere, the observatory began operations in 1963.
Since then, Arecibo has played a role in calculating how long a day on Mercury lasts, identifying the first extrasolar planets, and capturing radar images of celestial objects such as the “dog bone” asteroid known as Kleopatra.
Today, the observatory is part of the National Astronomy and Ionosphere Center, operated by Cornell University under an agreement with the National Science Foundation. About 140 full-time employees work at the observatory, plus a score or more of visiting researchers and students. A visitor center attracts 125,000 tourists annually. For residents, there’s a swimming pool, volleyball and basketball courts, a cafeteria that looks like Ma’s Diner, and housing facilities that range from motel-style dorm rooms (with no TV, but a high-speed Internet connection) to the cabin that Jodie Foster made famous in “Contact.”
There’s not much action at the pool, however: Researchers don’t expect high living at the Arecibo Observatory. “It’s not supposed to be a resort,” one resident said during the 90-minute drive from San Juan. And thanks to the control room’s Internet-based system for remote observing, the researchers don’t necessarily have to be in Arecibo at all.
Portalatin recalled that Penn State University’s Alex Wolszscan, the discoverer of those first extrasolar planets, was housebound in the middle of a snowstorm during some of his scheduled telescope time.
“Right from his home, in his bedroom, he was able to observe,” Portalatin said.
Full schedule ahead
The task of scheduling that time falls on the shoulders of Hector Hernandez, Arecibo’s service observing specialist. Amid the hum of the control room’s air conditioning, he sits down and fills in grids on a long sheet of paper, a task that could determine the career path of many an astronomer.
Hernandez also uses scheduling software to figure out whose project gets the telescope’s attention when — as well as when to fit in the necessary maintenance tasks. But there’s nothing like a long sheet of paper for showing six weeks’ worth of hourly blocks at a time.
“This is a time-consuming activity,” he said. Research proposals are accepted three times a year, then sent to referees for assessment, then prioritized by Arecibo’s scheduling committee. Projects with an “A” priority are guaranteed to get telescope time, “B” projects are conducted on a time-available basis, and “C” projects are done only if there are no “A” or “B” studies available for a particular open time.
“We have a lot of A’s and B’s we have to deal with,” Hernandez said.
The pressure could become greater as Arecibo’s capabilities expand and more astronomers clamor to study pulsars, black holes, gravitational waves, ionospheric phenomena and celestial radar targets — the observatory’s bread and butter. On the other hand, Arecibo’s highly visible role in the search for aliens could diminish as the SETI Institute turns its attention to the Allen Telescope Array, due for construction in California.
Altschuler, however, indicated that there’d always be a warm place in Arecibo’s heart for E.T.: The SETI Institute would get a sympathetic hearing “if they needed to continue” at Arecibo, he said. As for Serendip, “there’s absolutely no reason why they shouldn’t continue,” since the researchers operate their own receiver system on the radio telescope.
Will Arecibo’s new capabilities make it easier to bring in E.T.’s signal? What new discoveries will the seven-feed array make possible? As excited as Altschuler and Salter were about the mapping of the Milky Way, they said the biggest contributions of the new equipment couldn’t be foreseen.
“An instrument like this is useful for all kinds of searches,” Altschuler said. “The history of science is always that you open up a new window, and you see something unexpected.”