When was the arecibo observatory built

One reflector is 72 feet in diameter, the other, 26 feet. The whole structure is attached to trolleys that move along the foot-long curved feed arm suspended above the dish. Its range is as close as 4 miles 6 kilometers above the Earth to several billion light years away, at the edge of the known universe. It is sensitive enough to eavesdrop on a cellular phone conversation at the distance of Venus.

The new transmitter combined with the telescope forms the world's most powerful radar system. This can result in images of remarkable resolution: about one-half mile 1 km for the surface of Venus, down to 50 feet 15 meters for asteroids and comets.

That is sensitive enough to detect a steel golf ball at the distance of the moon. That is a constant. It never grows old. When the receiving platform at the legendary Arecibo Observatory came crashing down in a ton heap of twisted metal on Dec. Upon opening in , the telescope was called the Arecibo Ionosphere Observatory. Conceived by Cornell University electrical engineer William Gordon as an enormous radar to study the ionosphere, the facility was managed by Cornell and funded by the U.

Astronomy talked to Arecibo researchers who worked at the telescope throughout its long history. All interviews have been condensed and lightly edited for clarity. The Arecibo radio telescope stood for 57 years, working on the cutting edge of astronomical research. For most of its lifetime, it was the largest single radio telescope dish in the world, only surpassed in by the Five-hundred-meter Aperture Spherical Telescope in China.

The early years Gordon : Honestly, the observatory was built to study the upper atmosphere. Radar astronomy and radio astronomy were essentially fringe benefits. Donald Campbell, former Arecibo director: ARPA was interested in trying to figure out ways to detect incoming nuclear missiles by a wake that they might leave in the ionosphere.

While Gordon was primarily interested in studying the upper atmosphere, radio astronomers were intrigued as well. The field was still in its infancy, and the prospect of a facility as powerful as Arecibo drew attention. In , Gordon moved to Arecibo to supervise its construction, leading up to its dedication.

Gordon: It was a matter of who was in control, I guess. Gordon: It was Corson who finally, in , asked me to come back to Cornell. If you ask me, I was mad at the time. I thought I was removed from a job that I deserved to have. Gold is a very bright guy. He has lots of good ideas. Wait a minute. He has lots of ideas. Some of the ideas are good. But the people around him are snowed trying to sort out the good ideas from the chaff.

The big staff got along just fine with everybody. You always had occasional personal issues or something, but it was a very congenial group of people. Because to some degree, they were thrown together. And there was a lot of socializing that went on within the observatory, expatriate staff, et cetera. It was a lot of fun, actually, frankly. The staff was pretty young; there were quite a number of graduate students. Everybody was pretty excited about using it.

The Arecibo site lies in a natural concave sinkhole nestled in the karst mountains of Puerto Rico. On the pulse In , British astronomer Jocelyn Bell Burnell discovered radio pulses emanating from objects in space that were quickly dubbed pulsars. This unexpected find put radio astronomy front and center — and Arecibo took on a starring role. Campbell: Arecibo was perfect for pulsars. But Arecibo was equipped to do just that, because of the radars.

So everybody converted over to doing pulsars, including me. The first major upgrade to the facility began in and was completed in , greatly improving both its receiving and transmitting capabilities. In the s, pulsar astronomy continued to grow with the discovery of millisecond pulsars, which spin several hundred times per second.

For Aleksander Wolszczan, who arrived at Arecibo in from his native Poland, it was a heady time. There was a lot of stuff going on — I mean really, very good science. There was always a way to get some telescope time to test out some crazy stuff. A more powerful radar transmitter was also installed, allowing the telescope to better image potentially hazardous near-Earth asteroids. Six sets of auxiliary cables were installed, two on each tower, to handle the percent increase in platform weight.

Apparently, the Gregorian is a heavier weight than the structure was intended to support. Venus revealed Donald Campbell arrived at Arecibo in January , fresh from undergraduate studies in his native Australia. For his Ph. But the first-generation line feed did not perform as hoped. Campbell: This was the first time anyone had done something like this. And unfortunately, the line feed turned out to be far less efficient than expected, by about a factor of two.

So that limited the capabilities in terms of resolution as well. That changed in the —74 upgrade, when Arecibo received a more efficient line feed and a new high-power transmitter. Campbell: We got much, much improved images of Venus left — good enough to see craters and volcanoes and various other features on the surface. So for the first time, there were images covering about 30 percent of the surface of Venus that that you could actually interpret in terms of surface geology, so to speak.

That was pretty exciting. Arecibo stands completed in its initial configuration in August The first reflecting dish is made of a wire mesh through which the valley below can be seen. The line feed hangs over the reflector like a needle. Arecibo designer William Gordon stands on the catwalk over the dish that leads to the receiving platform. The only facility of its kind in Puerto Rico, it featured exhibits, an auditorium, and an observing deck with a spectacular view of the radio dish.

That was the reason I initially got into physics — because of Arecibo and the astronomy that was developed there. And a lot of people feel exactly the same way. The first exoplanets In , Arecibo underwent an extended period of maintenance.

Wolszczan: There were periodic inspections of the structure of the telescope. And during one, they actually discovered some signs of actual cracks in the structure supporting the platform, and they had to be replaced. Though the telescope was immobilized, science could still be done. Wolszczan: So I proposed to do a scientifically high-risk project, which was to look for millisecond pulsars away from the galactic disk.

Most of the types of searches, including millisecond pulsar searches at the time, were really focused on the galactic disk and the galactic center. But the variation in this pulsar was too irregular — as if there were something else pulling on the pulsar. Wolszczan was awarded more observing time and used Arecibo to track the pulsar regularly, and a clearer picture emerged. Wolszczan: A very interesting thing was that the amplitude of that effect was too small for a companion — or companions — to be stars.

When an auxiliary cable came out of its socket on Aug. Altschuler: I remember, even way before the Senior Review, that we were very worried about the future. We lived always under that Damocles sword. All those lines of investigation have now been shut down for good, although limited science will continue at some smaller facilities on the Arecibo site.

The cables that broke helped to support a tonne platform of scientific instruments, which hangs above the main telescope dish. The first cable slipped out of its socket and smashed panels at the edge of the dish, but the second broke in half and tore huge gashes in a central portion of the dish.

A second photograph, released this week by observatory officials, also reveals the destruction. These are some of the only public glimpses of the damage so far. A high-resolution satellite image of the Arecibo dish shows gashes in the main dish through which green vegetation below is visible.

Credit: Planet Labs, Inc. If any more cables fail — which could happen at any time — the entire platform could crash into the dish below.

Why ultra-powerful radio bursts are the most perplexing mystery in astronomy. So the NSF decided to close the Arecibo dish permanently. The closure comes as a shock to the wider astronomical community. A social-media campaign with the hashtag WhatAreciboMeansToMe sprung up almost immediately, with astronomers, engineers and other scientists — many from Puerto Rico — sharing stories of how the observatory had shaped their careers.

NSF officials insist that the cable failures came as a surprise. After the first, engineering teams spotted a handful of broken wires on the second cable, which was more crucial to holding up the platform, but they did not see it as a major problem because the weight it was carrying was well within its design capacity.

The main cable that failed experienced wire breaks shown before its sudden and unexpected collapse. But that main cable, which was installed in the early s, had apparently degraded over time. Over the years, external review committees have highlighted the ongoing need to maintain the ageing cables. Zauderer said that maintenance in recent years had been completed according to schedule. Before this year, the last major cable problems at the observatory were in January , when a magnitude