Atacama Large Millimeter Array (ALMA)
Atacama Desert, Chile
23° 1' 9.42" S, 67° 45' 11.44" W
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Ground breaking ceremony for the Atacama Large Millimeter Array (ALMA)

Scientists and dignitaries from Europe, North America and Chile are breaking ground today on what will be the world's largest, most sensitive radio telescope operating at millimeter wavelengths .

ALMA - the "Atacama Large Millimeter Array" - will be a single instrument composed of 64 high-precision antennas located in the II Region of Chile, in the District of San Pedro de Atacama, at the Chajnantor altiplano, 5,000 metres above sea level. ALMA 's primary function will be to observe and image with unprecedented clarity the enigmatic cold regions of the Universe, which are optically dark, yet shine brightly in the millimetre portion of the electromagnetic spectrum.

ALMA is an international astronomy facility. ALMA is an equal partnership between Europe and North America, in cooperation with the Republic of Chile, and is funded in North America by the U.S. National Science Foundation (NSF) in cooperation with the National Research Council of Canada (NRC), and in Europe by the European Southern Observatory (ESO) and Spain. ALMA construction and operations are led on behalf of North America by the National Radio Astronomy Observatory (NRAO), which is managed by Associated Universities, Inc. (AUI), and on behalf of Europe by ESO.

"ALMA will be a giant leap forward for our studies of this relatively little explored spectral window towards the Universe" , said Dr. Catherine Cesarsky , Director General of ESO. "With ESO leading the European part of this ambitious and forward-looking project, the impact of ALMA will be felt in wide circles on our continent. Together with our partners in North America and Chile, we are all looking forward to the truly outstanding opportunities that will be offered by ALMA , also to young scientists and engineers" .

"The U.S. National Science Foundation joins today with our North American partner, Canada, and with the European Southern Observatory, Spain, and Chile to prepare for a spectacular new instrument, " stated Dr. Rita Colwell , director of the U.S. National Science Foundation. " ALMA will expand our vision of the Universe with "eyes" that pierce the shrouded mantles of space through which light cannot penetrate." On the occasion of this groundbreaking, the ALMA logo was unveiled

SOURCE: ALMA Observatory
Atacama Large Millimeter Array
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The first successful movement of an ALMA antenna took place at the Operations Support Facility (OSF) on 8 July 2008. The antenna transporter "Lore", one of the two units manufactured by Scheuerle under contract by ESO and delivered recently at the OSF, has been used to move one 12-m antenna from their site erection facility to an external antenna pad for sky testing. 2008 - Source: www.eso.org/gallery

Atacama Large Millimeter Array
 

The Atacama Large Millimeter/submillimeter Array (ALMA) is an international astronomy project that consists of an astronomical interferometer formed from an array of radio telescopes, located at Llano de Chajnantor Observatory in the Atacama desert in northern Chile. The telescope is expected to revolutionize modern astronomy by providing an insight on star formation in the early universe and imaging local star and planet formation in great detail. With a cost in excess of one billion US dollars, it is the most ambitious ground-based telescope currently under construction.

Overview

The telescopes and their receivers are capable of detecting sub-millimeter and millimeter wavelengths. The array will have much higher sensitivity and higher resolution than existing sub-millimeter telescopes such as the single-dish James Clerk Maxwell Telescope or existing interferometer networks such as the Submillimeter Array or the IRAMPlateau de Bure facility. By moving the antennas at regular intervals, the resolution of the array and the size of object that can be imaged will be altered, producing a "zoom-lens" capability, similar to that employed at the VLA site in New Mexico. The high sensitivity is mainly achieved through the large numbers of telescopes that will make up the array. While sixty-four 12 metres (39 ft) dishes were originally envisaged, it is now possible that there will ultimately only be fifty built. The American and European partners have each placed orders for twenty-five antennas, with options for an additional seven. Japan is also contributing antennas in the form of the Atacama Compact Array (ACA) which will also be located at the ALMA site. By using smaller antennas than ALMA (twelve 7 m and four 12 m dishes are planned) larger fields of view can be imaged at a given frequency. The ability to move them closer together also results in the possibility to image sources of larger angular extent. The ACA will work together with ALMA in order to enhance the latter's wide-field imaging capability.

Controversy

The original plan was for the project to employ a single antenna design. The intent of testing the three prototype antennas was to compete the designs to down-select (choose the best). Three factors conspired to alter the plan:

  • The size of the antenna production contract is substantial.
  • It was politically expedient (or necessary) for each of the major partners to realize some non-scientific, economic return on their investment (see realpolitik).
  • No arrangement was found to break up the antenna production into parts that could be parceled to the partners.
The evaluation of the prototypes yielded each partner finding technical justification to favor their own prototype. Since there was no clear winner, the plan was changed to allow different antenna designs. Each partner is now funding production of a portion of the antennas via associated contractors. This is a workable solution which allows the project to complete without any significant descope (erosion) of the science capabilities. The disadvantages with this solution are:
  • The complexity of combining the electronic signals from different antenna designs is significantly increased.
  • The overall costs of funding multiple contractors with smaller contracts increases (see Economies of Scale).
  • The additional overhead of integrating different antenna designs and managing multiple contractors likely results in an overall schedule delay.
A positive result of the new plan is some reduction of risks. Because some productive science can be accomplished with partial completion of the array, both technical and schedule risks are reduced.

Funding

ALMA was initially a 50-50 collaboration between the European Southern Observatory (ESO) and the North American partners. The array has been extended with the help of the new Japanese, Taiwanese, Spanish and Chilean partners. ALMA is the largest and most expensive ground-based astronomical project currently under construction (current cost estimate is US$1.3 billion).

Partners

Assembly
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One of the antennas under construction.. In this photograph a European ALMA antenna takes shape at the observatory's Operations Support Facility (OSF). ALMA, the Atacama Large Millimetre/sub-millimetre Array, is a revolutionary astronomical telescope, comprising an array of 66 giant 12-metre and 7-metre diameter antennas observing at millimetre and sub-millimetre wavelengths. The telescope is being built on the breathtaking location of the Chajnantor plateau, at 5000 metres altitude in the Chilean Andes. The OSF, at which the antennas are being assembled and tested, is at an altitude of 2900 metres. Date 7 September 2009(2009-09-07) Source www.eso.org/gallery

The complex will be built primarily by European, U.S., Japanese and Canadian companies (including General Dynamics) and universities. Three prototype antennas have undergone evaluation at the Very Large Array site in New Mexico since 2002. General Dynamics C4 Systems signed a contract with Associated Universities, Inc. to provide twenty-five to thirty-two 12m antennas. Alcatel Alenia Space, a consortium of manufacturers from France, Italy, and Germany, has been signed up to provide twenty-five of the antennas, the largest-ever European industrial contract. The first antenna will be delivered in 2007, and the rest at about one per month, finishing in 2011.

Transporting antennas to the site

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The 130-ton ALMA antenna transporter "Otto" during its naming ceremony. A display of sheer size! The sub-compact SMART car "undertakes" the 130-ton ALMA antenna transporter "Otto" during the naming ceremony.
Date  25 August 2009(2009-08-25) Source  www.eso.org/gallery Author ESO/H.H.Heyer
 
Transporting the 115 tonne antennas from the base camp at 2900 m altitude to the site at 5000 m presents enormous problems. The solution chosen is to use two custom 28-wheel self-loading heavy haulers. The vehicles are made by Scheuerle Fahrzeugfabrik in Germany and each is 10 m wide, 20 m long and 6 m high, weighing 130 tonnes. They are powered by twin 500 kW diesel engines. The transporters, which feature a driver's seat designed to accommodate an oxygen tank to aid breathing the thin high-altitude air, can pick up the antennas and place them precisely at the site. The first vehicle was completed and tested in July 2007. Both transporters were delivered to the ALMA Operations Support Facility (OSF) in Chile on February 15, 2008. On July 7, 2008 an ALMA transporter for the first time moved an antenna, moving it from inside the antenna assembly building (Site Erection Facility) to a pad outside the building for testing (holographic surface measurements). The antenna was of the North American VertexRSI design.

General information

ALMA construction and operations are led on behalf of North America by the National Radio Astronomy Observatory (NRAO). NRAO is managed by Associated Universities, Inc (AUI). ALMA construction and operations are led on behalf of Europe by ESO and Japan by the National Astronomical Observatory of Japan (NAOJ). Administration of the ALMA site in Chile is lead by ESO.

Project detail

  • 50 to 64 antennas of 12 m diameter located at an elevation of 5,000 m at Llano de Chajnantor Observatory, enhanced by a compact array of 4 x 12 m and 12 x 7 m antennas (consortium currently considering to build 50 or 64
  • Imaging instrument in all atmospheric windows between 350 μm and 10 mm
  • Array configurations from approximately 150 m to 14 km
  • Spatial resolution of 10 milliarcseconds, 10 times better than the Very Large Array (VLA) and the Hubble Space Telescope
  • The ability to image sources arcminutes to degrees across at one arcsecond resolution
  • Velocity resolution under 50 m/s
  • Faster and more flexible imaging instrument than the Very Large Array
  • Largest and most sensitive instrument in the world at millimeter and submillimeter wavelengths

    • Point source detection sensitivity 20 times better than the Very Large Array
Project timeline
Timeline
Date Activity
May 1998 Start of Phase 1 (Design & Development).
June 1999 U.S./European Memorandum of Understanding for Design & Development.
February 2003 Final North American / European Agreement, with 50% of funding from ESO, and 50% of funding shared between USA and Canada.
September 2004 North American, European & Japanese draft agreement, with Japan providing new extensions to ALMA.
October 2004 Opening of Joint ALMA office, Santiago, Chile.
October 2005 Groundbreaking at 5000 m altitude Array Operation Site of ALMA.
September 2005 Taiwan joins the ALMA Project through Japan.
June 2006 N. American, European, & Japanese sign agreement on the Enhanced ALMA.
2010 Call for shared-risk early science proposals.
2012 ALMA construction complete.

See also

References
  1. EU ALMA Newsletter (Jan, 2005)
  2. US ALMA AAAC/NSF Update (Oct, 2005)
  3. ALMA Partners
  4. GD - 2005
  5. ESO - 2005
  6. Giant truck set for sky-high task." BBC News website, 30 July 2007. Retrieved 31 July 2007.
  7. July 2008 NRAO ALMA newsletter article by Dr. Al Wootten
External links SOURCE: Wikipedia Atacama_Large_Millimeter_Array

Llano de Chajnantor Observatory
CBI-2 radio telescope
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CBI-2 radio telescope Credit: by Astro-Norte

Llano de Chajnantor Observatory

Llano de Chajnantor Observatory is an astronomical observatory located at 5104 m altitude in the Chilean Atacama desert, 50 kilometers to the east of San Pedro de Atacama. It is a very dry site - inhospitable to humans - but an excellent site for submillimetre astronomy. Water vapour absorbs and attenuates submillimetre radiation and thus a dry site is required for this type of short-wavelength radio astronomy. It hosts some of the largest and most expensive astronomical telescopes in the world, with about 1 billion US dollars already allocated for projects on the site.

Chronology of telescopes

In 1999, the CBI was the first radio telescope to start observations under Chajnantor skies. In 2002, ASTE arrived at Pampa La Bola. Then: APEX in 2003, NANTEN2 in 2004, ACT in 2007. QUIET in 2008 and Mini-Tao in 2009. ALMA is under construction

Telescopes on the Llano de Chajnantor site

Telescopes on the adjacent Pampa La Bola site See also
Retrieved from Wikipedia Llano_de_Chajnantor_Observatory
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CBI-2 radio telescope
23° 1' 42.39" S, 67° 45' 41.00" W
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Llano de Chajnantor from Cerro Toco. APEX (left) and CBI (far center) can be seen. 
November 2004 Author  Ricardo Bustos
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