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Arecibo radio telescope

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Title: Arecibo radio telescope  
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Subject: Ionosphere, Radio telescope, Timeline of telescopes, observatories, and observing technology, 1036 Ganymed, 3908 Nyx, Daedalus (crater), Arecibo message, February 2005 in science, Woodruff T. Sullivan III
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Arecibo radio telescope

Arecibo Radio Telescope
Aerial view of the Observatory
Organization SRI International
Location Arecibo, Puerto Rico, USA
Wavelength electromagnetic spectrum: (3.00 cm to 1.00 meter)
Built completed in 1963
Telescope style spherical reflector
Diameter 1,000 ft (300 m)
Collecting area 73,000 square meters (790,000 sq ft)
Mounting semi-transit telescope: fixed primary with secondary (Gregorian reflector) and a delay-line feed, each of which moves on tracks to point to different parts of the sky.
Dome none
National Astronomy and Ionosphere Center
Arecibo Observatory

18°20′39″N 66°45′10″W / 18.34417°N 66.75278°W / 18.34417; -66.75278Coordinates: 18°20′39″N 66°45′10″W / 18.34417°N 66.75278°W / 18.34417; -66.75278

Area 118 acres (480,000 m2)
Architect Gordon, William E; Kavanaugh, T.C.
Governing body Federal
NRHP Reference # 07000525
Added to NRHP September 23, 2008[1]

The Arecibo Observatory is a radio telescope in the municipality of Arecibo, Puerto Rico. This observatory is operated by SRI International, USRA and UMET, under cooperative agreement with the National Science Foundation (NSF).[2][3] This observatory is also called the National Astronomy and Ionosphere Center, although "NAIC" refers to both the observatory and the staff that operates it.[4] From its construction in the 1960s until 2011, the observatory was managed by Cornell University.

The observatory's 1,000 ft (305 m) radio telescope is the world's largest single-aperture telescope. It is used in three major areas of research: radio astronomy, aeronomy, and radar astronomy. Scientists who want to use the telescope submit proposals that are evaluated by an independent scientific board.

The telescope has made appearances in motion picture and television productions and got more recognition in 1999 when it began to collect data for the SETI@home project. It has been listed on the American National Register of Historic Places beginning in 2008.[1][5] It was the featured listing in the National Park Service's weekly list of October 3, 2008.[6] The center was named an IEEE Milestone in 2001.[7]

Ángel Ramos Foundation Visitor Center

Opened in 1997, the Ángel Ramos Foundation Visitor Center

General information

The main collecting dish is 1,000 ft (305 m) in diameter, constructed inside the depression left by a karst sinkhole.[9] It contains the largest curved focusing dish on Earth, giving Arecibo the largest electromagnetic-wave-gathering capacity.[10] The dish surface is made of 38,778 perforated aluminum panels, each about 3 by 6 feet (1 by 2 m), supported by a mesh of steel cables. The ground underneath is accessible and supports shade-tolerant vegetation.[11]

The telescope has three radar transmitters, with effective isotropic radiated powers of 20 TW at 2380 MHz, 2.5 TW (pulse peak) at 430 MHz, and 300 MW at 47 MHz.

The telescope is a spherical reflector of radius 870 ft, not a parabolic reflector. To aim the telescope, the receiver is moved to intercept signals reflected from different directions by the spherical dish surface. A parabolic mirror would have varying astigmatism when the receiver is off the focal point, but the error of a spherical mirror is the same in every direction.

The receiver is on a 900-ton platform suspended 150 m (500 ft) above the dish by 18 cables running from three reinforced concrete towers, one 110 m (365 ft) high and the other two 80 m (265 ft) high, placing their tops at the same elevation. The platform has a 93-meter-long rotating bow-shaped track, called the azimuth arm, carrying the receiving antennas and secondary and tertiary reflectors. This allows the telescope to observe any region of the sky in a forty-degree cone of visibility about the local zenith (between −1 and 38 degrees of declination). Puerto Rico's location near the Northern Tropic allows Arecibo to view the planets in the Solar System over the Northern half of their orbit. The round trip light time to objects beyond Saturn is longer than the 2.6 hour time that the telescope can track a celestial position, preventing radar observations of more distant objects.

The Arecibo Telescope as viewed from the observation deck, October 2013

Design and architecture

The Arecibo telescope was built between mid-1960 and November 1963, and designed by William E. Gordon of Cornell University, who intended to use it to study Earth's ionosphere.[12][13][14] Originally, a fixed parabolic reflector was envisioned, pointing in a fixed direction with a 150 m (500 ft) tower to hold equipment at the focus. This design would have limited its use in other areas of research, such as planetary science and radio astronomy, which require the ability to point at different positions in the sky and to track those positions for an extended period as Earth rotates. Ward Low of the Advanced Research Projects Agency (ARPA) pointed out this flaw, and put Gordon in touch with the Air Force Cambridge Research Laboratory (AFCRL) in Boston, Massachusetts, where one group headed by Phil Blacksmith was working on spherical reflectors and another group was studying the propagation of radio waves in and through the upper atmosphere. Cornell University proposed the project to ARPA in mid-1958 and a contract was signed between the AFCRL and the University in November 1959. Cornell University and Zachary Sears published a request for proposals (RFP) asking for a design to support a feed moving along a spherical surface 435 feet (133 m) above the stationary reflector. The RFP suggested a tripod or a tower in the center to support the feed. At Cornell University on the day the project for the design and construction of the antenna was announced, Gordon had also envisioned a 435 ft (133 m) tower centered in the 1,000 ft (300 m) reflector to support the feed.

George Doundoulakis, who directed research at General Bronze Corporation in Garden City, New York, along with Zachary Sears, who directed Internal Design at Digital B & E Corporation, New York, received the RFP from Cornell University for the antenna design, and studied the idea of suspending the feed with his brother, Helias Doundoulakis, a civil engineer. George Doundoulakis identified the problem that a tower or tripod would have presented around the center, the most important area of the reflector, and devised a better approach by suspending the feed. He presented his proposal to Cornell for a doughnut truss suspended by four cables from four towers above the reflector, having along its edge a rail track for the azimuthal positioning of the feed. A second truss, in the form of an arc, or arch, was to be suspended below, which would rotate on the rails through 360 degrees. The arc also had rails on which the unit supporting the feed would move for the elevational positioning of the feed. A counter-weight would move symmetrically opposite to the feed for stability, and the entire feed could be lowered and raised if a hurricane were present. Helias Doundoulakis designed the cable suspension system which was finally adopted. Although the present configuration is substantially the same as the original drawings by George and Helias (though with three towers instead of the original four), the U.S. Patent office granted Helias a patent[15] for the brothers' innovative idea. William J. Casey, later to be the director of the Central Intelligence Agency under President Ronald Reagan, was also an assignee on the patent.

Construction began in mid-1960, with the official opening on November 1, 1963.[16] As the primary dish is spherical, its focus is along a line rather than at a single point (as would be the case for a parabolic reflector); therefore, complicated line feeds had to be used to carry out observations. Each line feed covered a narrow frequency band (2–5% of the center frequency of the band) and a limited number of line feeds could be used at any one time, limiting the flexibility of the telescope.

The telescope has been upgraded several times. Initially, when the maximum expected operating frequency was about 500 MHz, the surface consisted of half-inch galvanized wire mesh laid directly on the support cables. In 1974 a high-precision surface consisting of thousands of individually adjustable aluminum panels replaced the old wire mesh, and the highest usable frequency was raised to about 5,000 MHz. A Gregorian reflector system was installed in 1997, incorporating secondary and tertiary reflectors to focus radio waves at a single point. This allowed the installation of a suite of receivers, covering the whole 1–10 GHz range, that could be easily moved onto the focal point, giving Arecibo more flexibility. At the same time, a ground screen was installed around the perimeter to block the ground's thermal radiation from reaching the feed antennas, and a more powerful 2,400 MHz transmitter was installed.

Research and discoveries

Many scientific discoveries have been made using the Arecibo telescope. On April 7, 1964, shortly after it began operations, Gordon Pettengill's team used it to determine that the rotation rate of Mercury was not 88 days, as previously thought, but only 59 days.[17] In 1968, the discovery of the periodicity of the Crab Pulsar (33 milliseconds) by Lovelace and others provided the first solid evidence that neutron stars exist.[18] In 1974, Hulse and Taylor discovered the first binary pulsar PSR B1913+16,[19] an accomplishment for which they later received the Nobel Prize in Physics. In 1982, the first millisecond pulsar, PSR B1937+21, was discovered by Donald C. Backer, Shrinivas Kulkarni, Carl Heiles, Michael Davis, and Miller Goss.[20] This object spins 642 times per second, and until the discovery of PSR J1748-2446ad in 2005, it was the fastest-spinning pulsar known.

In August 1989, the observatory directly imaged an asteroid for the first time in history: 4769 Castalia.[21] The following year, Polish astronomer Aleksander Wolszczan made the discovery of pulsar PSR B1257+12, which later led him to discover its three orbiting planets and a possible comet.[22][23] These were the first extrasolar planets discovered. In 1994, John Harmon used the Arecibo radio telescope to map the distribution of ice in the poles of Mercury.[24]

In January 2008, detection of prebiotic molecules methanimine and hydrogen cyanide were reported from Arecibo Observatory radio spectroscopy measurements of the distant starburst galaxy Arp 220.[25]


The Arecibo message

Main article: Arecibo message

In 1974, the Arecibo message, an attempt to communicate with potential extraterrestrial life, was transmitted from the radio telescope toward the globular cluster M13, about 25,000 light-years away.[26] The 1,679 bit pattern of 1s and 0s defined a 23 by 73 pixel bitmap image that included numbers, stick figures, chemical formulas, and a crude image of the telescope itself.[27]

The RuBisCo Stars

Main article: RuBisCo Stars

On November 7, 2009, as part of the 35th anniversary of the Drake/Sagan transmission to M13 the RuBisCO gene sequence was transmitted to three “nearby” stars: GJ 83.1, Teagarden's star SO 025300.5+165258, and Kappa Ceti (G5B). The project was by artist Joe Davis with support from Paul Gilster, Arecibo Observatory, Cornell University, and various others.

SETI searches

Main article: SETI

Arecibo is the source of data for the SETI@home and Astropulse distributed computing projects put forward by the Space Sciences Laboratory at the University of California, Berkeley and was used for the SETI Institute's Project Phoenix observations.[28] The Einstein@Home distributed computing project has discovered more than 20 pulsars in Arecibo data.[29]

Other uses

Terrestrial aeronomy experiments at Arecibo have included the Coqui 2 experiment, which were supported by NASA. The telescope also has had military intelligence uses; among them, locating Soviet radar installations by detecting their signals bouncing off the Moon.

Funding issues

A report by the division of Astronomical Sciences of the National Science Foundation, made public on November 3, 2006, recommended substantially decreased astronomy funding for Arecibo Observatory, ramping down from $10.5 million in 2007 to $4.0 million in 2011.[30][31] If other sources of money could not be obtained, the observatory would have to close. The report also advised that 80 percent of the observation time be allocated to the surveys already in progress, reducing the time available for smaller programs. NASA gradually eliminated its share of the planetary radar funding at Arecibo from 2001 thorough 2006.[32]

Academics and researchers responded by organizing to protect and advocate for the observatory. They established the Arecibo Science Advocacy Partnership (ASAP), which was meant to advance the scientific excellence of Arecibo Observatory research and to publicize its accomplishments in astronomy, aeronomy and planetary radar.[33] ASAP's goals include mobilizing the existing broad base of support for Arecibo science within the fields it serves directly, the broad scientific community; provide a forum for the Arecibo research community and enhance communication within it; promote the potential of Arecibo for groundbreaking science; suggest the paths that will maximize it into the foreseeable future; showcase the broad impact and far-reaching implications of the science currently carried out with this unique instrument.[33]

Contributions by the government of Puerto Rico may be one way to help fill the funding gap, but are controversial and uncertain. At town hall meetings about the potential closure, Puerto Rican Senate President Kenneth McClintock announced an initial local appropriation of $3.0 million during fiscal year 2008 to fund a major maintenance project to restore the three pillars that hold up the antenna platform to their original condition, pending inclusion in the next bond issue.[34] The bond authorization, with the $3.0 million appropriation, was approved by the Senate of Puerto Rico on November 14, 2007, on the first day of a special session called by Aníbal Acevedo Vilá.[35] The Puerto Rico House of Representatives repeated this action on June 30, 2008. The Governor of Puerto Rico signed the measure into law in August 2008.[36] These funds were made available in the second half of 2009.

José Enrique Serrano, a member of the U.S. House of Representatives Appropriations Committee, asked the National Science Foundation to keep Arecibo in operation in a letter published on September 19, 2007.[37]

Language similar to that in the letter of September 19 was included in the FY-2008 omnibus spending bill. In October 2007, Puerto Rico's then-Resident Commissioner, Luis Fortuño, along with Dana Rohrabacher, filed legislation to assure the continued operation of the observatory.[38] A similar bill was filed in the U.S. Senate in April 2008 by the junior Senator from New York, Hillary Clinton.[39]

Since the Arecibo observatory is owned by the Government of the United States, direct donations by private or corporate donors cannot be made. However, as non-profit (501(c)(3)) "public charities" under US law, Cornell University and subsequently SRI International can accept contributions on behalf of the Arecibo Observatory.[40]

In September 2007, in an open letter to researchers, the NSF clarified the status of the budget for NAIC, stating that the present plan could hit the targeted budgetary revision.[41] No mention of private funding was made. However, it need be noted that the NSF is undertaking studies to mothball or demolish the observatory to return it to its natural setting in the event that its budget target is not reached.

In November 2007, The Planetary Society urged the U.S. Congress to prevent the Arecibo Observatory from closing because of insufficient funding since its radar contributes greatly to the accuracy of predictions of asteroid impacts on the Earth.[42] The Planetary Society believes that continued operation of the observatory will reduce the cost of mitigation (that is, deflection of a near-Earth asteroid on collision to Earth), should that be necessary.

Also in November of that year The New York Times described the consequences of the budget cuts at the site.[43] In July 2008, the British newspaper The Daily Telegraph reported that the funding crisis, due to federal budget cuts, was still very much alive.[44]

The SETI@home program is using the telescope as a primary source for the research. The program is urging people to send a letter to their political representatives, in support of full federal funding of the observatory.[45]

The NAIC received $3.1 million from the American Recovery and Reinvestment Act of 2009, and this was used for basic maintenance and for a second, much smaller, antenna to be used for very long baseline interferometry, new Klystron amplifiers for the planetary radar system, and for student training.[46] This allotment was an increase of around 30 percent over the FY-2009 budget. However, the FY-2010 funding request by NSF was cut by $1.2 million (−12.5 percent) over the FY-2009 budget) in light of their continued plans to reduce funding.[47]

The 2011 NSF budget was reduced by a further $1.6 million, −15 percent compared to 2010, with a further $1.0 million reduction projected by FY-2014.[48] Beginning in FY-2010, NASA began contributing $2.0 million per year for planetary science, particularly the study of near-Earth objects, at Arecibo. NASA implemented this funding through its Near Earth Object Observations program.[49]

Also in 2010, the NSF issued a call for new proposals for the management of NAIC beginning in FY-2012.[4] On May 12, 2011, the agency informed Cornell University that it would no longer be the operator of the NAIC, and thus of the Arecibo Observatory, as of October 1, 2011. At that time, Cornell transferred its operations to SRI International, along with two other managing partners, Universities Space Research Association and Universidad Metropolitana de Puerto Rico, with a number of other collaborators.[3][50] Upon the award of the new cooperative agreement for NAIC management and operation, NSF also decertified NAIC as a Federally Funded Research and Development Center (FFRDC),[48] with the stated goal of providing the NAIC with greater freedom to establish broader scientific partnerships and pursue funding opportunities for activities beyond the scope of those supported by the NSF.[51]

In popular culture

  • The Arecibo Observatory was featured on Cosmos: A Personal Voyage in Part 12 "Encyclopaedia Galactica."
  • The Arecibo Observatory is featured at the end of James Burke's TV series Connections in Part 3 "Distant Voices."
  • Arecibo Observatory was used as a filming location in the climax of the James Bond movie GoldenEye (1995) and as a level in the accompanying Nintendo 64 videogame GoldenEye 007.
  • Season 2 episode 22 of the cartoon Jackie Chan Adventures featured a spoof of the James Bond movie GoldenEye, and similarly ended the plot at the Arecibo Observatory.
  • The film Contact (1997), based on the Carl Sagan 1985 novel of the same name, features Arecibo, where the main character uses the facility as part of a SETI project.
  • Fox Mulder was sent to the Arecibo Observatory in The X-Files episode "Little Green Men".
  • Songwriter and author Jimmy Buffett mentions the "giant telescope" in his book Where Is Joe Merchant?, and in the lyrics to the song "Desdemona's Building A Rocket Ship".
  • The musicians Boxcutter, Lustmord, and Little Boots have all released albums named Arecibo.
  • The observatory is featured in the film Species (1995), the James Gunn novel The Listeners (1972), the Robert J. Sawyer novel Rollback, and the Mary Doria Russell novel The Sparrow.
  • Arecibo Observatory also featured in the action movie The Losers (2010).
  • In the video game Just Cause 2 there is a large radio observatory called PAN MILSAT that is very similar in appearance to Arecibo Observatory.
  • Internet radio station Arecibo Radio is named after the observatory.[52]
  • The Arecibo Observatory was featured in an episode Covert Affairs called "Loving the Alien" as a stand-in for the Lourdes SIGINT Station.
  • The Arecibo Observatory was mentioned in an episode of Korean TV Drama Playful Kiss in 2010.
  • The Arecibo Observatory is part of the backstory in the Ingress/Niantic LabsARG (2012).
  • An observatory similiar to the Arecibo Observatory is featured in Battlefield 4 as a multiplayer map named "Rogue Transmission".

Arecibo Observatory Directors

See also

Puerto Rico portal


Further reading

  • Entry into the National Register of Historic Places

External links

  • Arecibo Observatory
  • Arecibo Science Advocacy Partnership
  • Ángel Ramos Foundation Visitor Center
  • SETI@home
  • IEEE History Center – IEEE Milestones: NAIC/Arecibo Radiotelescope
  • Lofar
  • The Arecibo Observatory Contributions Site
  • Letter to save Arecibo Observatory
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