Milestones:First Digitally Processed Image from a Spaceborne Synthetic Aperture Radar, 1978 and Milestones:NAIC/Arecibo Radiotelescope, 1963: Difference between pages

Revision as of 18:46, 6 January 2015

NAIC/Arecibo Radiotelescope, 1963

Arecibo, Puerto Rico, November 2001, IEEE Puerto Rico & Caribbean Section

(IEEE Milestone and ASME Landmark)

The Arecibo Observatory, the world's largest radiotelescope, was dedicated in 1963. Its design and implementation led to advances in the electrical engineering areas of antenna design, signal processing, and electronic instrumentation, and in the mechanical engineering areas of antenna suspension and drive systems. The drive system positions all active parts of the antenna with millimeter precision, regardless of temperature changes, enabling the telescope to maintain an accurate focus. Its subsequent operation led to advances in the scientific fields of radioastronomy, planetary studies, and space and atmospheric sciences.

The plaque can be viewed at the Arecibo observatory, approximately 20 km south of Arecibo, Puerto Rico, at the end of road 625.

In order to use radio waves to explore space, scientists had to overcome one crucial obstacle: the weakness of cosmic signals. Cosmic radio signals are so weak, in fact, that all the energy collected by all the radio telescopes on our planet during the more than sixty-year history of radio astronomy amounts to no more than the energy released when a few raindrops hit the ground. An enormously sensitive collector of radio waves, such as the giant Arecibo radio-radar telescope, was needed to capture these signals. The Arecibo radar telescope was conceived by William E. Gordon, then a professor of electrical engineering at Cornell University. Gordon wanted to study the properties of the Earth's upper atmosphere, the ionosphere, and thought that he could use a radar system to measure the density and temperature in this difficult-to-study atmospheric region. His calculations indicated that an antenna approximately 305 meters (1,000 feet) in diameter would do the job, but would be far too expensive to build using existing designs for radio and radar antennas. To construct a telescope of the size he needed, Gordon hit on the idea of using a spherical, bowl-shaped reflector fixed in the ground, with a movable receiver hanging above it. This permitted the beam to point in a 20-degree range of directions around the zenith, or overhead direction. Such a telescope would be most useful in a location where the Sun, Moon, and planets pass almost directly overhead. Puerto Rico offered the extra advantage of Karst terrain-small, deep valleys surrounded by limestone hills-and a natural sinkhole south of the city of Arecibo provided an economical way to support the spherical reflector. Built in three years, the Arecibo Ionospheric Observatory began operations in 1963. Gordon's concept of using radar to study the ionosphere-called incoherent scatter radar-was successful. In addition, the telescope allowed radio measurements of a host of objects in the solar system, in our galaxy, and beyond. Arecibo Observatory is now part of the National Astronomy and Ionosphere Center (NAIC), a national research center operated by Cornell University under cooperative agreement with the National Science Foundation. The observatory is used by scientists from all parts of the United States and around the world.

With the completion in 1997 of the $25 million Gregorian reflector system suspended 137 meters (450 feet) above the telescope's 305-meter (1 ,000-foot) diameter dish, together with the construction of a ground screen and powerful new radar transmitter, the Arecibo telescope remains unmatched in its sensitivity and versatility for radio studies of the atmosphere, the solar system, and the universe.

Facts & Figures

Arecibo Observatory sits on a 48-hectare (118-acre) site outside of the city of Arecibo, Puerto Rico. There are 140 staff members at the site, and another fifteen at NAIC headquarters on the Cornell University campus in Ithaca, New York.
The observatory cost $9.3 million when it was completed in 1963. The 1974 upgrade cost another $9 million. The most recent upgrade completed in 1997, the addition of the Gregorian, a new radar transmitter, and ground screen cost $25 million. If the entire facility were to be built today, it would cost in excess of $100 million.
More than 8 kilometers (five miles) of 2.5 cm. (1-inch)-thick steel cables and approximately 40 kilometers (25 miles) of 0.6 cm. (quarter-inch)-thick cables support the reflector. They keep it from changing shape as temperatures fluctuate and winds blow.
The dish, 305 meters (1,000 feet) across, has a surface area of eighteen acres, the equivalent of 26 football fields.
An on-site plant processed 270,000 kg (300 tons) of aluminum to fabricate the perforated panels that form the spherical surface. There are 38,778 of them, each measuring 101 cm. x 203 cm. (40 x 80 inches).
Arecibo's azimuth arm is 93 meters (304 feet) long, 3.7 meters (12 feet) wide, and 10 meters (33) feet deep. It rotates on a circular track 42.7 meters (140 feet) in diameter.
There are three towers supporting the structure. One is 111 meters (365 feet) high, and the other two are each 81 meters (265 feet) high. All three tops are at the same elevation.
The 363 kilometers (227 miles) of aluminum angle used to make the frames supporting the main reflector panels could have made a guardrail all the way around the island of Puerto Rico.
The dome that houses the Gregorian reflectors is six stories high, is suspended 137 meters (450 feet) above the main reflector, and, although made of aluminum to minimize its weight, still weighs 68,000 kg (75 tons).

Dedication Ceremony

<youtube>xniCER6LV0A</youtube>

Map

Loading map...

@@ Line 1: / Line 1: @@
-{{MilestoneLayout|citation=In November 1978, a team from MacDonald, Dettwiler and Associates Ltd. (MDA) became the first to use a digital processor to reconstruct an image from Seasat-A, the first civilian spaceborne synthetic aperture radar (SAR). MDA engineers subsequently developed three of the four most important SAR digital processing algorithms that replaced the optical processing methods used previously.|gps=13800 Commerce Parkway  Richmond, BC V6V 2J3
+== NAIC/Arecibo Radiotelescope, 1963  ==
-latitude, longitude:	49.1753696, -123.0704193|plaque=We propose to mount the plaque in the lobby of MDA's headquarters.|secured=The plaque will be located in the lobby, which is outside the secure area of the building. All visitors to MDA will be able to view the plaque alongside other historical exhibits including a scale model of the Prince Albert Earth Station, the Canadarm, etc.|significance=From the time that Carl A. Wiley of Goodyear Aircraft Co. introduced the synthetic aperture radar (SAR) concept in 1951, optical correlators based upon various combinations of exotic lenses and optical film had been used to reconstruct synthetic aperture radar imagery. While reconstruction could be accomplished in reasonable time using such techniques, the results suffered from various artifacts associated with slight physical imperfections in the optical system and the limited dynamic range of the optical system. While the possibility of using digital technology to process SAR data had been recognized early on, the processing requirements greatly exceeded the capabilities of the general purpose computers available to researchers in the 1950's and 1960's. The state of the art as of 1970 is summarized in [1].
-At the same time, it had been recognized that a synthetic aperture radar carried by an orbiting satellite would offer many important advantages over airborne SARs. First, orbiting Earth observation satellites can achieve worldwide coverage with an ease that airborne platforms cannot match. Second, orbiting SARs are not buffeted by the atmospheric turbulence that shakes airborne SARs; the path that they take through airless space is ultra smooth and highly predictable. These advantages are only partially offset by the reduced resolution and lower signal-to-noise ratio achievable with orbital SAR imagery due to their much greater height above the Earth's surface.
-Tremendous advances in minicomputer technology during the early 1970's renewed interest in the possibility of placing a synthetic aperture radar in low earth orbit and using general purpose computers to produce high quality imagery from the downlinked data. Seasat-A. the world's first orbital SAR, was launched by NASA in 1978. Although it failed within 90 days of achieving orbit due to a power system defect, Seasat-A demonstrated the enormous potential of orbital SARs and ushered in three decades of innovation that saw orbital SARs of ever increasing power and capability launched by NASA, the European Space Agency and the Canadian Space Agency.
-Several teams competed to be the first to reconstruct a scene by digitally processing Seasat-A SAR data. However, the general purpose minicomputers available to engineers in the late 1970's were only barely capable of supplying the enormous processing power required. It was widely expected that a large, well-funded team from NASA's Jet Propulsion Laboratory would prevail. Instead, a small, upstart team from Canada's MacDonald Dettwiler and Associates that had begun their task two years earlier won the race in November 1978 [2].
-So significant was the accomplishment that this first image was featured in the 26 February 1979 issue of Aviation Week and Space Technology [3]. Details were reported at several conferences early in 1979 [4],[5]. JPL was behind and as recently as 1980 was still reporting results that had been processed using the less capable optical techniques [6].|features=The events of November 1978 marked a turning point in the history of synthetic aperture radar. Demonstration that data from spaceborne SARs could be digitally processed using general purpose digital computers helped to dramatically  reduce the cost of SAR imagery and make it much more widely available for civilian applications. Until 1978, military applications of SAR were predominant. Since 1978, civilian applications of SAR have assumed steadily increasing importance.
-The reputation that MDA earned from this accomplishment fuelled its rapid growth into the world's largest supplier of SAR processors and Canada's largest space technology company.|references=[1] R. O. Harger, |support=}}
-<div class="header"><span class="head1">INNOVATION</span><span class="head2">  MAP</span></div>
+[[Image:Arecibo Radiotelescope.jpg|thumb]]Arecibo, Puerto Rico, November 2001, [[IEEE Puerto Rico & Caribbean Section History|IEEE Puerto Rico &amp; Caribbean Section]]
-<googlemap controls="small" height="250" width="300" zoom="10" lon="-123.0704193" lat="49.1753696" version="0.9">
+(IEEE Milestone and [http://www.asme.org/about-asme/history/landmarks ASME Landmark])&nbsp;
-.1753696, -123.0704193,
-Single-element Unidirectional Microphone - Shure Unidyne, 1939,
+''The Arecibo Observatory, the world's largest radiotelescope, was dedicated in 1963. Its design and implementation led to advances in the electrical engineering areas of antenna design, signal processing, and electronic instrumentation, and in the mechanical engineering areas of antenna suspension and drive systems. The drive system positions all active parts of the antenna with millimeter precision, regardless of temperature changes, enabling the telescope to maintain an accurate focus. Its subsequent operation led to advances in the scientific fields of radioastronomy, planetary studies, and space and atmospheric sciences.''
-Niles, IL, U.S.A
-</googlemap>
+'''The plaque can be viewed at the Arecibo observatory, approximately 20 km south of Arecibo, Puerto Rico, at the end of road 625.'''
+In order to use radio waves to explore space, scientists had to overcome one crucial obstacle: the weakness of cosmic signals. Cosmic radio signals are so weak, in fact, that all the energy collected by all the radio telescopes on our planet during the more than sixty-year history of radio astronomy amounts to no more than the energy released when a few raindrops hit the ground. An enormously sensitive collector of radio waves, such as the giant Arecibo radio-radar telescope, was needed to capture these signals. The Arecibo radar telescope was conceived by William E. Gordon, then a professor of electrical engineering at Cornell University. Gordon wanted to study the properties of the Earth's upper atmosphere, the ionosphere, and thought that he could use a radar system to measure the density and temperature in this difficult-to-study atmospheric region. His calculations indicated that an antenna approximately 305 meters (1,000 feet) in diameter would do the job, but would be far too expensive to build using existing designs for radio and radar antennas. To construct a telescope of the size he needed, Gordon hit on the idea of using a spherical, bowl-shaped reflector fixed in the ground, with a movable receiver hanging above it. This permitted the beam to point in a 20-degree range of directions around the zenith, or overhead direction. Such a telescope would be most useful in a location where the Sun, Moon, and planets pass almost directly overhead. Puerto Rico offered the extra advantage of Karst terrain-small, deep valleys surrounded by limestone hills-and a natural sinkhole south of the city of Arecibo provided an economical way to support the spherical reflector. Built in three years, the Arecibo Ionospheric Observatory began operations in 1963. Gordon's concept of using radar to study the ionosphere-called incoherent scatter radar-was successful. In addition, the telescope allowed radio measurements of a host of objects in the solar system, in our galaxy, and beyond. Arecibo Observatory is now part of the National Astronomy and Ionosphere Center (NAIC), a national research center operated by Cornell University under cooperative agreement with the National Science Foundation. The observatory is used by scientists from all parts of the United States and around the world.
+With the completion in 1997 of the $25 million Gregorian reflector system suspended 137 meters (450 feet) above the telescope's 305-meter (1 ,000-foot) diameter dish, together with the construction of a ground screen and powerful new radar transmitter, the Arecibo telescope remains unmatched in its sensitivity and versatility for radio studies of the atmosphere, the solar system, and the universe.
+== Facts &amp; Figures ==
+*Arecibo Observatory sits on a 48-hectare (118-acre) site outside of the city of Arecibo, Puerto Rico. There are 140 staff members at the site, and another fifteen at NAIC headquarters on the Cornell University campus in Ithaca, New York.
+*The observatory cost $9.3 million when it was completed in 1963. The 1974 upgrade cost another $9 million. The most recent upgrade completed in 1997, the addition of the Gregorian, a new radar transmitter, and ground screen cost $25 million. If the entire facility were to be built today, it would cost in excess of $100 million.
+*More than 8 kilometers (five miles) of 2.5 cm. (1-inch)-thick steel cables and approximately 40 kilometers (25 miles) of 0.6 cm. (quarter-inch)-thick cables support the reflector. They keep it from changing shape as temperatures fluctuate and winds blow.
+*The dish, 305 meters (1,000 feet) across, has a surface area of eighteen acres, the equivalent of 26 football fields.
+*An on-site plant processed 270,000 kg (300 tons) of aluminum to fabricate the perforated panels that form the spherical surface. There are 38,778 of them, each measuring 101 cm. x 203 cm. (40 x 80 inches).
+*Arecibo's azimuth arm is 93 meters (304 feet) long, 3.7 meters (12 feet) wide, and 10 meters (33) feet deep. It rotates on a circular track 42.7 meters (140 feet) in diameter.
+*There are three towers supporting the structure. One is 111 meters (365 feet) high, and the other two are each 81 meters (265 feet) high. All three tops are at the same elevation.
+*The 363 kilometers (227 miles) of aluminum angle used to make the frames supporting the main reflector panels could have made a guardrail all the way around the island of Puerto Rico.
+*The dome that houses the Gregorian reflectors is six stories high, is suspended 137 meters (450 feet) above the main reflector, and, although made of aluminum to minimize its weight, still weighs 68,000 kg (75 tons).
+== Dedication Ceremony ==
+<youtube>xniCER6LV0A</youtube>
+== Map ==
+{{#display_map:18.344424, -66.753144~ ~ ~ ~ ~Arecibo Observatory, Arecibo, Puerto Rico|height=250|zoom=10|static=yes|center=18.344424, -66.753144}}
+[[Category:Environment|Radiotelescope]] [[Category:Atmosphere|Radiotelescope]] [[Category:Ionosphere|Radiotelescope]] [[Category:Fields, waves & electromagnetics|Radiotelescope]] [[Category:Antennas|Radiotelescope]] [[Category:Antennas|Radiotelescope]] [[Category:Radio astronomy|Radiotelescope]] [[Category:Signals|Radiotelescope]] [[Category:Signal detection|Radiotelescope]]