Arecibo Observatory

Beez Neez
Skipper and First Mate Millard (Big Bear and Pepe)
Fri 12 Feb 2010 22:49
Arecibo Observatory




After breakfast at the Coral by the Sea, we drove toward Arecibo, followed the windy road to the Observatory. Our first glimpse. The sign at the gate.




They take sponsorship from wide and varied companies, this endorsement from 7up. The first exhibit in the very informative Visitors Centre

The Angel Ramos Foundation Visitor Center opened in 1997, the Angel Ramos Foundation Visitor Centre features interactive exhibits and displays about the operations of the radio telescope, astronomy and atmospheric science. The center is named after the foundation created by Angel Ramos, the founder of Telemundo, which provided one half of the construction costs for building the centre.




Big Bear in fascinated learning mode, a veritable "boys toys" type of place.


 The Arecibo Observatory is a radio telescope located close to the city of Arecibo. It is operated by Cornell University under cooperative agreement with the National Science Foundation. The observatory works as the National Astronomy and Ionosphere Center (NAIC) although both names are officially used to refer to it. NAIC more properly refers to the organization that runs both the observatory and associated offices at Cornell University. The observatory's three hundred and five metre radio telescope is the largest single-aperture telescope ever constructed and nestles a depression left by a karst sinkhole. It carries out three major areas of research: radio astronomy, aeronomy (using both the 305 m telescope and the observatory's lidar facility), and radar astronomy observations of solar system objects. Usage of the telescope is gained by submitting proposals to the observatory, which are evaluated by an independent board of referees. The dish is the largest curved focusing dish on Earth, giving Arecibo the largest electromagnetic-wave-gathering capacity. The Arecibo telescope's dish surface is made of 38,778 perforated aluminum panels, each measuring about six feet by three, supported by a mesh of steel cables. The centre was listed on the US National Register of Historic Places in 2008.




A piece of Mars called the Zagami Village Meteorite and Bear stroking Gibeon - found in Namibia in 1836, it is iron-octahedrite and weighs three hundred and fifty pounds


In 1962, a farmer chasing crows away from his cornfield near Zagami Rock village in Nigeria, heard a very loud explosion, followed by a thud and a puff of smoke. A forty pound piece of Mars had landed about ten feet from him, burying itself in a two foot hole. The meteorite was recovered and taken to a museum. Now known as the Zagami Meteorite, it is the largest piece of Mars ever recovered on the Earth. Most meteorites discovered are small fragments of comets or asteroids. But a small number have been identified as coming from the Moon or Mars, about two dozen. The Zagami Meteorite started off as a volcanic rock that cooled on the surface of Mars about two hundred million years ago. A comet slammed into Mars about three million years ago, launching a meteor weighing about three hundred and thirty pounds into space. As it crossed the Earth's atmosphere in about 1962, it disintegrated to the surviving meteorite that fell in the farmers field in Zagami Rock village. This was cut in various sizes for study, tests and analysis, this piece weighs twenty eight grams.

OK so I learned something I had always wanted to understand. The Cosmic Landscape is immense. To use miles or kilometres to measure distances would quickly take up pages of zeros. As a result, astronomers have developed new units of measurement for these large distances. For example, to measure distances to objects that are relatively nearby, astronomers often use the mean distance between the Earth and the Sun as a yardstick. This distance, which is roughly one hundred and fifty million kilometres, is called one "Astronomical Unit", or 1 AU. Jupiter is 5.2 AU from the sun. Another unit of measurement is the "Light Year". This is the distance light will travel in a vacuum in one year. Light is used because nothing can travel faster. Since light travels about three hundred thousand kilometres per second, in a year it will have gone about ninety billion kilometres. For this reason, if you travel to the moon at one hundred kilometres per hour, it will take you about four thousand hours or one hundred and sixty six days, but light takes a bit over a second. It will take eight minutes for light from the Sun to reach Earth. It takes four years for light from Proxima Centauri, the nearest known star.

This means that when we look at distant celestial objects from Earth, we "see" these objects not as they are today, but as they were when light left them. Astronomers studying light (electromagnetic radiation) from these objects are looking back in time. This means astronomy can be like a time machine - the astrological equivalent of digging through geological strata on Earth.




What I just learned was exhibited in several examples in the Visitors Centre, this is one of them.


This bit is for serious geeks and the interested


The telescope: has three radar transmitters, with effective isotropic radiated powers of 20TW at 2380 MHz, 2.5TW (pulse peak) at 430 MHz, and 300MW at 47 MHz. The telescope is a spherical reflector (as opposed to a parabolic reflector). This form is due to the method used to aim the telescope: the telescope's dish is fixed in place, and the receiver is repositioned to intercept signals reflected from different directions by the spherical dish surface. A parabolic mirror would induce a varying astigmatism when the receiver is in different positions off the focal point, but the error of a spherical mirror is the same in every direction. The receiver is located on a nine hundred ton platform which is suspended five hundred feet in the air above the dish by eighteen cables running from three reinforced concrete towers, one of which is 110 m (365 ft) high and the other two of which are two hundred and sixty five feet high (the tops of the three towers are at the same elevation). The platform has a ninety three metre long rotating bow-shaped track called the azimuth arm on which receiving antennas, secondary and tertiary reflectors are mounted. This allows the telescope to observe any region of the sky within a forty degree cone of visibility about the local zenith (between -1 and 38 degrees of declination). Puerto Rico's location near the equator allows Arecibo to view all of the planets in the solar system, though the round trip light time to objects beyond Saturn is longer than the time the telescope can track it, preventing radar observations of more distant objects.

Design and architecture

A detailed view of the beam-steering mechanism and some antennas. The triangular platform at the top is fixed, and the azimuth arm rotates beneath it. To the left is the Gregorian sub-reflector, and to the right is the ninety six foot long line feed tuned to 430 MHz. Just visible at the upper right is part of the rectangular waveguide that brings the 2.5 MW 430 MHz radar transmitter's signal up to the focal region.

The construction of the Arecibo telescope was initiated in the summer of 1960 and completed in November 1963 by Professor William E Gordon of Cornell University, who originally intended to use it for the study of Earth's ionosphere. Originally, a fixed parabolic reflector was envisioned, pointing in a fixed direction with a five hundred foot tower to hold equipment at the focus. This design would have had a very limited use for other potential 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 a 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 the summer of 1958 and a contract was signed between the AFCRL and the University in November 1959. Cornell University 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.

George Doundoulakis, director of research for the antenna design company General Bronze Corp in Garden City, N.Y. received the RFP from Cornell and studied it with his brother, Helias Doundoulakis, a civil engineer. The brothers devised a more efficient way to suspend the feed, and finally designed the cable suspension system that was used in final construction. The US Patent Office granted Helias Doundoulakis a patent on this approach.

Construction began in the summer of 1960, with the official opening on the 1st of November 1963. 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), thus 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 undergone significant upgrades. 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 5000 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 a new 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 2400 MHz transmitter was installed.

Research and discoveries

Many significant scientific discoveries have been made using the Arecibo telescope. On the 7th April 1964, shortly after its inauguration, 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. 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 in the Universe. In 1974 Hulse and Taylor (Don, you busy boy) discovered the first binary pulsar PSR B1913+16, for which they were later awarded 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. 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. 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. These were the first extra-solar planets ever discovered. In 1994, John Harmon used the Arecibo radio telescope to map the distribution of ice in the poles of Mercury. 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.




Joseph H Taylor and his Nobel Prize Certificate




The actual Nobel Prize front and back. Bear and I have had the privilege of talking to a Nobel Laureate. When we asked about the most nerve racking bit - he answered - "Signing the book". Apparently you get taken into a very long room, handed a quill pen and shown where to sign in the book, he said he was OK until he looked up the list of signatures and saw the likes of Einstein and his hand began to shake. A stern headmistress type lady took the quill from him, stood him in the corner with a scrap of paper and a biro until he could do it. She led him back to the great book, told him not to make a mess of HER book and get on with it.


Other usage

The telescope also had military intelligence uses, for example locating Soviet radar installations by detecting their signals bouncing back off the Moon. Arecibo is also the source of data for the SETI {CHANGE TO AT} 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. In 1974, the Arecibo message, an attempt to communicate with extraterrestrial life, was transmitted from the radio telescope toward the globular cluster M13, about 25,000 light-years away. 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. Terrestrial aeronomy experiments include the Coqui 2 experiment.

Funding issues

A report by the division of Astronomical Sciences of the National Science Foundation, made public on 2006-11-03, recommended substantially decreased astronomy funding for Arecibo Observatory, ramping down from USD 10.5M in 2007 to USD 4M in 2011. If other sources of funding cannot be obtained, this would mean the closure of the observatory. The report also advised that 80% of the observation time be allocated to the surveys already in progress, reducing the time available for other scientific work. NASA gradually eliminated its share of the planetary radar funding at Arecibo from 2001–2006.

There have been all kinds of Government talks re funding - even a suggestion that Google be allowed to pay for advertising on the telescope.

................ A similar bill was filed in the United States Senate in April, 2008 by the junior Senator from New York, Hilary Clinton. Interesting

In July 2008, our own - Daily Telegraph reported that the funding crisis, due to federal budget cuts, was still very much alive. The SETI {CHANGE TO AT} 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.





Arecibo in popular culture

The telescope is visually distinctive and has been used in the filming of notable motion picture and television productions: as the villain's antenna in the James Bond movie GoldenEye, as itself in the film Contact, the X-Files episode Little Green Men, and the docu-drama Super Comet: After the Impact. The Arecibo Observatory was also featured in the film Species, as the main setting for the James Gunn novel The Listeners (1972), and as a prominent element in the Mary Doria Russell novel The Sparrow (1996).