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59-463: The Green Bank Telescope operates at meter to millimeter wavelengths. Its 100-meter diameter collecting area, unblocked aperture, and good surface accuracy provide superb sensitivity across the telescope's full 0.1–116 GHz operating range. The GBT is fully steerable, and 85 percent of the local celestial hemisphere is accessible. It is used for astronomy about 6500 hours every year, with 2000–3000 hours per year going to high-frequency science. Part of

118-549: A Stewart platform coupled with virtual reality to do advanced biomechanical and clinical research. Dr. J. Charles Taylor used the Stewart platform to develop the Taylor Spatial Frame , an external fixator used in orthopedic surgery for the correction of bone deformities and treatment of complex fractures. The Ampelmann system is a motion-compensated gangway using a Stewart platform. This allows access from

177-411: A few minutes. Operational frequencies range from 290 MHz to 115 GHz. As an azimuth-elevation mounting telescope, the azimuth adjustments are driven by four trucks with four wheels each on a 210-foot (64 m) diameter rail. The 16 thirty-horsepower motors can change azimuth at the rate of up to 40 degrees per minute. Azimuth axis is also supported by a pintle bearing at the center point of

236-797: A joint project between the two observatories with participation by Canada and Spain (the latter became a member of ESO later). A series of resolutions and agreements led to the choice of "Atacama Large Millimeter Array", or ALMA, as the name of the new array in March 1999 and the signing of the ALMA Agreement on 25 February 2003, between the North American and European parties. ("Alma" means "soul" in Spanish and "learned" or "knowledgeable" in Arabic.) Following mutual discussions over several years,

295-730: A large angular size, such as molecular clouds and nearby galaxies. The antennae forming the Atacama Compact Array, four 12-meter antennae and twelve 7-meter antennae, were produced and delivered by Japan. In 2013, the Atacama Compact Array was named the Morita Array after Professor Koh-ichiro Morita, a member of the Japanese ALMA team and designer of the ACA, who died on 7 May 2012 in Santiago. In August 2013, workers at

354-453: A subtotal of fifty antennae, that compose the main array. The participating East Asian countries are contributing 16 antennae (four 12-meter diameter and twelve 7-meter diameter antennae) in the form of the Atacama Compact Array (ACA), which is part of the enhanced ALMA. By using smaller antennae than the main ALMA array, larger fields of view can be imaged at a given frequency using ACA. Placing

413-475: A young (100,000-1,000,000-year-old) system, so the new data spurred renewed theories of protoplanetary development. One theory suggests that the faster accretion rate might be due to the complex magnetic field of the protoplanetary disc. ALMA participated in the Event Horizon Telescope project, which produced the first direct image of a black hole , published in 2019. ALMA participated in

472-500: Is an international partnership amongst Europe , the United States , Canada , Japan , South Korea , Taiwan , and Chile . Costing about US$ 1.4 billion, it is the most expensive ground-based telescope in operation. ALMA began scientific observations in the second half of 2011 and the first images were released to the press on 3 October 2011. The array has been fully operational since March 2013. The initial ALMA array

531-776: Is awaiting additional measurements . The Atacama Large Millimeter/submillimeter Array (ALMA), an international astronomy facility, is a partnership of Europe, North America and East Asia in cooperation with the Republic of Chile. ALMA is funded in Europe by the European Southern Observatory (ESO), in North America by the U.S. National Science Foundation (NSF) in cooperation with the National Research Council of Canada (NRC) and

590-422: Is commonly referred to as a motion base . It is sometimes called a six-axis platform or 6-DoF platform because of its possible motions and, because the motions are produced by a combination of movements of multiple actuators, it may be referred to as a synergistic motion platform , due to the synergy (mutual interaction) between the way that the actuators are programmed. Because the device has six actuators, it

649-597: Is composed of 66 high-precision antennae, and operates at wavelengths of 3.6 to 0.32 millimeters (31 to 1000 GHz). The array has much higher sensitivity and higher resolution than earlier submillimeter telescopes such as the single-dish James Clerk Maxwell Telescope or existing interferometer networks such as the Submillimeter Array or the Institut de Radio Astronomie Millimétrique (IRAM) Plateau de Bure facility. The antennae can be moved across

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708-517: Is extensively used in flight simulators , particularly in the full flight simulator which requires all 6 degrees of freedom. This application was developed by Redifon , whose simulators featuring it became available for the Boeing 707, Douglas DC-8, Sud Aviation Caravelle , Canadair CL-44 , Boeing 727 , Comet, Vickers Viscount , Vickers Vanguard , Convair CV 990 , Lockheed C-130 Hercules , Vickers VC10 , and Fokker F-27 by 1962. In this role,

767-553: Is how to mix the two. James S. Albus of the National Institute of Standards and Technology (NIST) developed the Robocrane , where the platform hangs from six cables instead of being supported by six jacks. The Low Impact Docking System developed by NASA uses a Stewart platform to manipulate space vehicles during the docking process. The Computer Assisted Rehabilitation Environment developed by Motek Medical uses

826-527: Is often called a hexapod (six legs) in common usage, a name which was originally trademarked by Geodetic Technology for Stewart platforms used in machine tools . This specialised six-jack layout was first used by V E (Eric) Gough of the UK and was operational in 1954, the design later being publicised in a 1965 paper by D Stewart to the UK Institution of Mechanical Engineers . In 1962, prior to

885-463: Is to use two custom 28-wheel self-loading heavy haulers . The vehicles were made by Scheuerle Fahrzeugfabrik  [ de ] in Germany and are 10 m wide, 20 m long and 6 m high, weighing 130 tonnes. They are powered by twin turbocharged 500 kW Diesel engines . The transporters, which feature a driver's seat designed to accommodate an oxygen tank to aid breathing

944-584: Is used to scan for radio signals possibly emitted by extraterrestrial technologies. In late 2017, the telescope was used to scan ʻOumuamua for signs of extraterrestrial intelligence . Atacama Large Millimeter Array The Atacama Large Millimeter/submillimeter Array ( ALMA ) is an astronomical interferometer of 66 radio telescopes in the Atacama Desert of northern Chile , which observe electromagnetic radiation at millimeter and submillimeter wavelengths . The array has been constructed on

1003-484: The Allegheny Mountains shield it from some radio interference. The telescope's location has been the site of important radio astronomy telescopes since 1957. It currently houses seven additional telescopes, and in spite of its somewhat remote location, receives about 40,000 visitors each year. The structure weighs 7,600 metric tons (8,400 short tons) and is 485 feet (148 m) tall. The surface area of

1062-539: The COVID-19 pandemic . It also delayed the cycle 8 proposal submission deadline and suspended public visits to the site. On October 29, 2022, ALMA suspended observations due to a cyber attack. Observations were restarted 48 days later, on December 16, 2022. Stewart platform A Stewart platform is a type of parallel manipulator that has six prismatic actuators , commonly hydraulic jacks or electric linear actuators , attached in pairs to three positions on

1121-488: The National Astronomical Observatory of Japan (NAOJ). The Joint ALMA Observatory (JAO) provides the unified leadership and management of the construction, commissioning and operation of ALMA. Its current director since February 2018 is Sean Dougherty . The ALMA regional centre (ARC) has been designed as an interface between user communities of the major contributors of the ALMA project and

1180-835: The National Science Council of Taiwan (NSC) and in East Asia by the National Institutes of Natural Sciences of Japan (NINS) in cooperation with the Academia Sinica (AS) in Taiwan. ALMA construction and operations are led on behalf of Europe by ESO, on behalf of North America by the National Radio Astronomy Observatory (NRAO), which is managed by Associated Universities, Inc (AUI) and on behalf of East Asia by

1239-476: The Very Large Array since 2002. General Dynamics C4 Systems and its SATCOM Technologies division was contracted by Associated Universities, Inc. to provide twenty-five of the 12 m antennae, while European manufacturer Thales Alenia Space provided the other twenty-five principal antennae (in the largest-ever European industrial contract in ground-based astronomy). Japan's Mitsubishi Electric

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1298-656: The Very Long Baseline Array , and other high-angular resolution interferometers. Facilities of the Green Bank Observatory are also used for other scientific research, for many programs in education and public outreach, and for training students and teachers. The telescope began regular science operations in 2001, making it one of the newest astronomical facilities of the US National Science Foundation (NSF). It

1357-475: The inverse kinematics of rotary actuators also exists, as shown by Robert Eisele Stewart platforms have applications in flight simulators, machine tool technology, animatronics , crane technology, underwater research, simulation of earthquakes, air-to-sea rescue, mechanical bulls , satellite dish positioning, the Hexapod-Telescope , robotics, and orthopedic surgery. The Stewart platform design

1416-592: The 5,000 m (16,000 ft) elevation Chajnantor plateau – near the Llano de Chajnantor Observatory and the Atacama Pathfinder Experiment . This location was chosen for its high elevation and low humidity , factors which are crucial to reduce noise and decrease signal attenuation due to Earth's atmosphere. ALMA provides insight on star birth during the early Stelliferous era and detailed imaging of local star and planet formation. ALMA

1475-543: The ALMA Project received a proposal from the National Astronomical Observatory of Japan (NAOJ) whereby Japan would provide the ACA (Atacama Compact Array) and three additional receiver bands for the large array, to form Enhanced ALMA. Further discussions between ALMA and NAOJ led to the signing of a high-level agreement on 14 September 2004 that makes Japan an official participant in Enhanced ALMA, to be known as

1534-642: The Atacama Large Millimeter/submillimeter Array (ALMA) for the first time, that detailed the distribution of HCN , HNC , H 2 CO , and dust inside the comae of comets C/2012 F6 (Lemmon) and C/2012 S1 (ISON) . An image of the protoplanetary disc surrounding HL Tauri (a very young T Tauri star in the constellation Taurus ) was made public in 2014, showing a series of concentric bright rings separated by gaps, indicating protoplanet formation. As of 2014 , most theories did not expect planetary formation in such

1593-437: The Atacama Large Millimeter/submillimeter Array. A groundbreaking ceremony was held on November 6, 2003 and the ALMA logo was unveiled. During an early stage of the planning of ALMA, it was decided to employ ALMA antennae designed and constructed by known companies in North America, Europe, and Japan, rather than using one single design. This was mainly for political reasons. Although very different approaches have been chosen by

1652-775: The GBT in that fiscal year. The facility then began looking for partners to help fund its $ 10 million annual operating costs. On October 1, 2016, the National Radio Astronomy Observatory at Green Bank separated from the NSF and began accepting funding from private sources to stay operational as an independent institution, the Green Bank Observatory . The telescope is a key facility of the Breakthrough Listen project, in which it

1711-445: The GBT is a 100 by 110 meter active surface with 2,209 actuators (small motors used to adjust the position) for the 2,004 surface panels, making the total collecting area of 2.3 acres (9,300 m). The panels are made from aluminum manufactured to a surface accuracy of better than 50 micrometres (0.0020 in) RMS . The actuators adjust the panel positions to compensate for sagging, or bending under its own weight, which changes as

1770-572: The JAO. Activates for operating the ARC have also divided into the three main regions involved (Europe, North America and East Asia). The European ARC (led by ESO ) has been further subdivided into ARC-nodes located across Europe in Bonn-Bochum-Cologne, Bologna, Ondřejov, Onsala , IRAM (Grenoble), Leiden and JBCA (Manchester). The core purpose of the ARC is to assist the user community with

1829-695: The antennae closer together enables the imaging of sources of larger angular extent. The ACA works together with the main array in order to enhance the latter's wide-field imaging capability. ALMA has its conceptual roots in three astronomical projects: the Millimeter Array (MMA) of the United States, the Large Southern Array (LSA) of Europe, and the Large Millimeter Array (LMA) of Japan. The first step toward

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1888-411: The azimuth track. The elevation wheel structure provides tilting capability to adjust elevations between 5 and 95 degrees. The 98-foot (30 m) radius bull gear on the elevation wheel is driven by eight 40 horsepower motors with a capability of changing the elevations up to 20 degrees per minute. The 98-foot (30 m) long and 8-foot (2.4 m) diameter elevation shaft provides primary support of

1947-412: The claimed detection of phosphine , a biomarker, in the air of Venus. As no known non-biological source of phosphine on Venus could produce phosphine in the concentrations detected, this would have indicated the presence of biological organisms in the atmosphere of Venus. Later reanalyses cast doubt on the detection, although later analyses confirmed the results. The detection remains controversial, and

2006-522: The creation of what would become ALMA came in 1997, when the National Radio Astronomy Observatory (NRAO) and the European Southern Observatory (ESO) agreed to pursue a common project that merged the MMA and LSA. The merged array combined the sensitivity of the LSA with the frequency coverage and superior site of the MMA. ESO and NRAO worked together in technical, science, and management groups to define and organise

2065-652: The desert plateau over distances from 150 m to 16 km, which will give ALMA a powerful variable "zoom", similar in its concept to that employed at the centimeter-wavelength Very Large Array (VLA) site in New Mexico, United States . The high sensitivity is mainly achieved through the large numbers of antenna dishes that make up the array. The telescopes were provided by the European, North American and East Asian partners of ALMA. The American and European partners each provided twenty-five 12-meter diameter antennae, for

2124-550: The dish as a radar transmitting antenna to observe solar system objects such as asteroids. In 2002, astronomers detected three new millisecond pulsars in the globular cluster Messier 62 . In 2006, several discoveries were announced, including a large coil-shaped magnetic field in the Orion molecular cloud , and a large hydrogen gas superbubble 23,000 light years away, named the Ophiuchus Superbubble . In 2019,

2183-417: The feed horn in front of the 8 m subreflector. For Gregorian focus operation, the prime focus boom is retracted. The subreflector, positioned by a Stewart platform with 6 degrees of freedom, reflects incoming radio waves toward eight higher-frequency feeds on a rotating turret located on top of the receiver room. The computerized controlled turret can rotate a particular receiver into the position within

2242-507: The first three antennae were transported one-by-one to the Array Operations Site. At the end of 2009, a team of ALMA astronomers and engineers successfully linked three antennae at the 5,000-metre (16,000 ft) elevation observing site thus finishing the first stage of assembly and integration of the fledgling array. Linking three antennae allows corrections of errors that can arise when only two antennae are used, thus paving

2301-638: The future as the scale of the array continues to increase. The target of the observation was a pair of colliding galaxies with dramatically distorted shapes, known as the Antennae Galaxies . Although ALMA did not observe the entire galaxy merger, the result is the best submillimeter-wavelength image ever made of the Antennae Galaxies, showing the clouds of dense cold gas from which new stars form, which cannot be seen using visible light. On 11 August 2014, astronomers released studies, using

2360-685: The heart of the United States National Radio Quiet Zone , a unique area located in the town of Green Bank, West Virginia, where authorities limit all radio transmissions to avoid emissions toward the GBT and the Sugar Grove Station . The location of the telescope within the Radio Quiet Zone allows for the detection of faint radio-frequency signals which human-made signals might otherwise mask. The observatory borders National Forest land, and

2419-678: The help of the other Japanese, Taiwanese, and Chilean partners. ALMA is the largest and most expensive ground-based astronomical project, costing between US$ 1.4 and 1.5 billion. (However, various space astronomy projects including the Hubble Space Telescope , the James Webb Space Telescope , and several major planet probes have cost considerably more). The complex was built primarily by European, U.S., Japanese, and Canadian companies and universities . Three prototype antennae have undergone evaluation at

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2478-709: The most massive neutron star PSR J0740+6620 to date was detected. Since 2004, 28 new complex molecules have been discovered in the interstellar medium with the Green Bank Telescope. In response to limited budgetary issues, the Division of Astronomical Sciences (AST) of the National Science Foundation (NSF) commissioned a portfolio review committee, which conducted its work between September 2011 and August 2012. The committee, which reviewed all AST-supported facilities and activities,

2537-474: The original Stewart platform had a slightly different design, while others argue that the contributions of all three engineers should be recognized. In industrial applications, linear actuators (hydraulic or electric) are typically used for their simple and unique inverse kinematics closed form solution and their good strength and acceleration. For prototyping and low budget applications, typically rotary servo motors are used. A unique closed form solution for

2596-403: The payload is a replica cockpit and a visual display system, normally of several channels, for showing the outside-world visual scene to the aircraft crew that are being trained. Similar platforms are used in driving simulators , typically mounted on large X-Y tables to simulate short term acceleration. Long term acceleration can be simulated by tilting the platform, and an active research area

2655-499: The platform's baseplate, crossing over to three mounting points on a top plate. All 12 connections are made via universal joints . Devices placed on the top plate can be moved in the six degrees of freedom in which it is possible for a freely-suspended body to move: three linear movements x, y, z (lateral, longitudinal, and vertical), and the three rotations (pitch, roll, and yaw). Stewart platforms are known by various other names. In many applications, including in flight simulators, it

2714-479: The preparation of observing proposals, ensure observing programs meet their scientific goals efficiently, run a help-desk for submitting proposals and observing programs, delivering the data to principal investigators, maintenance of the ALMA data archive, assistance with the calibration of data and providing user feedback. The Atacama Compact Array, ACA, is a subset of 16 closely separated antennae that will greatly improve ALMA's ability to study celestial objects with

2773-489: The providers, each of the antenna designs appears to be able to meet ALMA's stringent requirements. The components designed and manufactured across Europe were transported by specialist aerospace and astrospace logistics company Route To Space Alliance, 26 in total which were delivered to Antwerp for onward shipment to Chile. ALMA was initially a 50-50 collaboration between the National Radio Astronomy Observatory and European Southern Observatory (ESO) and later extended with

2832-404: The publication of Stewart's paper, American engineer Klaus Cappel independently developed the same hexapod. Klaus patented his design and licensed it to the first flight simulator companies, and built the first commercial octahedral hexapod motion simulators. Although the title Stewart platform is commonly used, some have posited that Gough–Stewart platform is a more appropriate name because

2891-589: The scientific strength of the GBT is its flexibility and ease of use, allowing for rapid response to new scientific ideas. It is scheduled dynamically to match project needs to the available weather. The GBT is also readily reconfigured with new and experimental hardware. The high-sensitivity mapping capability of the GBT makes it a vital complement to the Atacama Large Millimeter Array , the Expanded Very Large Array ,

2950-420: The side of the dish, so that it and its retractable support boom do not obstruct the incoming radio waves, as occurs in conventional radio telescope designs with the feed located on the telescope's beam axis. The 200-foot (61 m) offset support arm houses a prime focus receiver on a retractable boom in front of a subreflector , and a receiver room. For prime focus operation, the boom is extended to position

3009-428: The telescope moves. Without this so-called "active surface" adjustment, observations at frequencies above 4 GHz would not be as efficient. Unusual for a radio telescope, the primary reflector is an off-axis segment of a paraboloid. This is the same design used in smaller (eg., 45-100cm) home satellite television dishes. The asymmetric reflector allows the telescope's focal point and feed horn to be located at

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3068-412: The telescope went on strike to demand better pay and working conditions. This is one of the first strikes to affect an astronomical observatory. The work stoppage began after the observatory failed to reach an agreement with the workers' union. After 17 days an agreement was reached providing for reduced schedules and higher pay for work done at high altitude. In March 2020, ALMA was shut down due to

3127-670: The thin high-altitude air, place the antennae precisely on the pads. The first vehicle was completed and tested in July 2007. Both transporters were delivered to the ALMA Operations Support Facility (OSF) in Chile on 15 February 2008. On 7 July 2008, an ALMA transporter moved an antenna for the first time, from inside the antenna assembly building (Site Erection Facility) to a pad outside the building for testing (holographic surface measurements). During Autumn 2009,

3186-471: The way for precise, high-resolution imaging. With this key step, commissioning of the instrument began 22 January 2010. On 28 July 2011, the first European antenna for ALMA arrived at the Chajnantor plateau, 5,000 meters above sea level, to join 15 antennae already in place from the other international partners. This was the number of antennae specified for ALMA to begin its first science observations, and

3245-456: The wheel structure. The elevation wheel also contains concrete-filled counterweight to balance with the surface and the feed arm structure. Because of its height (at 148 meters or 485 feet tall, it is 60% taller than the Statue of Liberty ) and bulk (16 million pounds), locals sometimes refer to the GBT as the “Great Big Thing”. The telescope's capabilities include the ngRADAR system which use

3304-574: Was composed of 17 external scientists and chaired by Daniel Eisenstein of Harvard University. As part of the committee's August 2012 recommendation for the closure of six facilities, was that the Robert C. Byrd Green Bank Telescope (GBT) should be defunded over a five-year period. In July 2014, the United States Senate Committee on Appropriations approved the NSF's fiscal year 2014 budget, which did not call for divestment of

3363-455: Was constructed following the collapse of a previous telescope at Green Bank, the 300 Foot Radio Telescope , a 90.44 m paraboloid that began observations in October 1961. This previous telescope collapsed on 15 November 1988 due to the failure of a gusset plate in the box girder assembly, which was a key component for the structural integrity of the telescope. The telescope sits near

3422-588: Was contracted to assemble NAOJ's 16 antennae. The antennae were delivered to the site from December 2008 to September 2013. Transporting the 115  tonne antennae from the Operations Support Facility at 2900 m altitude to the site at 5000 m, or moving antennae around the site to change the array size, presents enormous challenges; as portrayed in the television documentary Monster Moves: Mountain Mission . The solution chosen

3481-470: Was therefore an important milestone for the project. In October 2012, 43 of the 66 antennae had been set up. By the summer of 2011, sufficient telescopes were operational during the extensive program of testing prior to the Early Science phase for the first images to be captured. These early images gave a first glimpse of the potential of the new array that will produce much better quality images in

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