APEX & ALMA - Sub-millimetre Astronomy

[Waspie_Dwarf]

Sub-millimetre Astronomy in Full Swing on Southern Skies

The European Southern Observatory (ESO) press release 24-06 is reproduced below:

13 July 2006
For Immediate Release

Sub-millimetre Astronomy in Full Swing on Southern Skies

Impressive set of APEX Results to be published in Special Issue of Astronomy & Astrophysics

The Atacama Pathfinder Experiment (APEX) 12-m sub-millimetre telescope lives up to the ambitions of the scientists by providing access to the "Cold Universe" with unprecedented sensitivity and image quality. As a demonstration, no less than 26 articles based on early science with APEX are published this week in the research journal Astronomy & Astrophysics. Among the many new findings, most in the field of star formation and astrochemistry, are the discovery of a new interstellar molecule, and the detection of light emitted at 0.2 mm from CO molecules, as well as light coming from a charged molecule composed of two forms of Hydrogen.

Using both APEX and the IRAM 30-metre telescope the first astronomical detection of a charged molecule composed of Carbon and Fluorine - the 'CF+ ion' - was made. Prior to this discovery, only one fluorine-containing molecular species had been found in space so far, the HF molecule ('hydrogen fluoride'), consisting of one atom of Hydrogen and one of Fluorine. The newly discovered molecule, produced through a reaction between Carbon and the HF molecule, was found in a region adjoining the Orion Nebula, one of the nearest and most active stellar nurseries in the Milky Way. This detection provides support to the astronomers' understanding of interstellar fluorine chemistry, suggesting that hydrogen fluoride is ubiquitous in interstellar gas clouds.


The Atacama Pathfinder Experiment (APEX) 12-m sub-millimetre telescope started delivering scientific results at an amazing pace.

Another premiere is the detection - also in the Orion star-forming region - of light emitted by carbon monoxide (CO) at a wavelength of 0.2 mm. These short wavelengths are very difficult to investigate, both because the water vapour in the atmosphere attenuates the signal even more severely than elsewhere in the submillimeter range, but also because they are at the limit of the telescope's operating range. The detection of CO at these wavelengths, the very shortest accessible from Earth in any of the submillimeter 'windows', proves the superb efficiency of APEX.

Light coming from a charged molecule composed of Hydrogen and Deuterium (H2D+) was detected in several cold clouds in the Southern Sky. The H2D+ ion is interesting because it traces gas so cold (a few degrees above the absolute zero!) that only a few molecular species have not frozen out onto the surfaces of dust grains.

These are not the only significant discoveries made. Other highlights include the first observations of atomic carbon in the so-called "Pillars of Creation" in the Eagle Nebula (also known as Messier 16), a sub-millimetre study of a massive hot core, of a high-mass star forming region, as well as of a high velocity outflow coming from a young stellar object. Studies of molecular regions in the dwarf galaxy NGC 6822 and in the starburst galaxy NGC 253 were also done, proving that APEX can also contribute to the exploration of extragalactic objects.

Apart from the astronomical studies, a series of contributions deal with the technical aspects of APEX, such as the telescope itself, its software, its receivers and spectrometers. The latter were developed at the Max-Planck-Institut für Radioastronomie in Bonn, Germany and at the Swedish Chalmers University, while the 0.2 mm receiver was developed at the University of Cologne (Germany).


The APEX telescope is located on the Chajnantor plateau, in the Atacama Desert, at 5100-m altitude, close to the site where ALMA will be operating.

The APEX telescope, designed to work at sub-millimetre wavelengths, in the 0.2 to 1.5 mm range, passed successfully its Science Verification phase in July 2005 (see ESO PR 18/05 and ESO PR 25/05), and since then is performing regular science observations. It is located on the 5100 m high Chajnantor plateau in the Atacama Desert (Chile), probably the driest place on Earth. It is a collaborative effort between the Max-Planck-Institut für Radioastronomie, ESO and the Onsala Space Observatory (Sweden).

With its precise antenna and large collecting area, APEX provides, at this exceptional location, unprecedented access to a whole new domain in astronomical observations. Indeed, millimetre and sub-millimetre astronomy opens exciting new possibilities in the study of the first galaxies to have formed in the Universe and of the formation processes of stars and planets. It also allows astronomers to study the chemistry and physical conditions of molecular clouds, that are dense regions of gas and dust in which new stars are forming.

APEX is the pathfinder to the ALMA project. In fact, it is a modified ALMA prototype antenna and is located at the future site of the ALMA observatory. ALMA will consist of a giant array of 12-m antennas separated by baselines of up to 14 km and is expected to gradually start operation by the end of the decade.

The Astronomy & Astrophysics special issue (volume 454 no.2 - August I, 2006) on APEX first results includes 26 articles. They are freely available in PDF format from the publisher web site.

These results are partly based on APEX science verification data that are available from the ESO archive at http://www.eso.org/science/apexsv/.

More information on APEX is available at http://www.apex-telescope.org/

Source: ESO Press Release pr-24-06

[Waspie_Dwarf]

The Antenna Bride and Bridegroom

The European Southern Observatory (ESO) press release 10-07 is reproduced below:

ESO 10/07 - ALMA Release

7 March 2007
For Immediate Release

The Antenna Bride and Bridegroom

ALMA Achieves Major Milestone With Antenna-Link Success

The Atacama Large Millimeter/submillimeter Array (ALMA), an international telescope project, reached a major milestone on 2 March, when two 12-m ALMA prototype antennas were first linked together as an integrated system to observe an astronomical object.

"This achievement results from the integration of many state-of-the-art components from Europe and North America and bodes well for the success of ALMA in Chile", said Catherine Cesarsky, ESO's Director General.


The two ALMA Prototype Antennas at the ATF site in Socorro, New Mexico. The 2 antennas have been linked together as an integrated
system to observe Saturn on 2 March, paving the way for the future full operation of ALMA.

The milestone achievement, technically termed 'First Fringes', came at the ALMA Test Facility (ATF), located near Socorro in New Mexico. Faint radio waves emitted by the planet Saturn were collected by two ALMA prototype antennas, then processed by new, high-tech electronics to turn the two antennas into a single, high-resolution telescope system, called an interferometer. The planet's radio emissions at a frequency of 104 gigahertz were tracked by the ALMA system for more than an hour.

Such pairs of antennas are the basic building blocks of the multi-antenna imaging system ALMA. In such a system, the signals recorded by each antenna are electronically combined with the signals of every other antenna to form a multitude of pairs. Each pair contributes unique information that is used to build a highly detailed image of the astronomical object under observation. When completed in the year 2012, ALMA will have 66 antennas.

"Our congratulations go to the dedicated team of scientists, engineers and technicians who produced this groundbreaking achievement for ALMA. Much hard work and many long hours went into this effort, and we appreciate it all. This team should be very proud today," said NRAO Director Fred K.Y. Lo. "With this milestone behind us, we now can proceed with increased confidence toward completing ALMA," he added.

ALMA, located at an elevation of 5,000m in the Atacama Desert of northern Chile, will provide astronomers with the world's most advanced tool for exploring the Universe at millimetre and submillimetre wavelengths. ALMA will detect fainter objects and be able to produce much higher-quality images at these wavelengths than any previous telescope system. Scientists are eager to use this transformational capability to study the first stars and galaxies that formed in the early Universe, to learn long-sought details about how stars are formed, and to trace the motion of gas and dust as it whirls toward the surface of newly-formed stars and planets.

"The success of this test is fundamental proof that the hardware and software now under development for ALMA will work to produce a truly revolutionary astronomical tool," said Massimo Tarenghi, the ALMA Director.

In addition to the leading-edge electronic and electro-optical hardware and custom software that proved itself by producing ALMA's first fringes, the system's antennas are among the most advanced in the world. The stringent requirements for the antennas included extremely precise reflecting surfaces, highly accurate ability to point at desired locations in the sky, and the ability to operate reliably in the harsh, high-altitude environment of the ALMA site.

The ALMA Test Facility operates the two prototype antennas built by Alcatel Alenia Space and European Industrial Engineering in Europe, and by VertexRSI (USA). These antennas were evaluated individually at the ATF. Both prototypes were equipped with electronic equipment for receiving, digitizing and transmitting signals to a central facility, where the signals are combined to make the antennas work together as a single astronomical instrument.

"The successful achievement of recording the first fringes with two ALMA antennas is certainly an important milestone in the scientific program," said Hans Rykaczewski, the European ALMA Project Manager. "It is encouraging and adds to our motivation to see that the principles of ALMA work - not only scientifically, but also from the point of view of organizing this project by partners located in four continents. This successful partnership is a good proof of principle for the future of large scientific projects in astronomy."

The Atacama Large Millimeter/submillimeter Array (ALMA), an international astronomy facility, is a partnership among Europe, Japan and North America, in cooperation with the Republic of Chile. ALMA is funded in Europe by the European Organisation for Astronomical Research in the Southern Hemisphere, in Japan by the National Institutes of Natural Sciences (NINS) in cooperation with the Academia Sinica in Taiwan and in North America by the U.S. National Science Foundation (NSF) in cooperation with the National Research Council of Canada (NRC). ALMA construction and operations are led on behalf of Europe by ESO, on behalf of Japan by the National Astronomical Observatory of Japan (NAOJ) and on behalf of North America by the National Radio Astronomy Observatory (NRAO), which is managed by Associated Universities, Inc. (AUI).

Source: ESO Press Release pr-10-07

[Waspie_Dwarf]

A Roof for ALMA

The European Southern Observatory (ESO) press release 13-07 is reproduced below:

ESO 13/07 - ALMA Release

14 March 2007
For Immediate Release

A Roof for ALMA

Roof-Topping Ceremony Held for the ALMA OSF

On 10 March, an official ceremony took place on the 2,900m high site of the Atacama Large Millimeter/submillimeter Array (ALMA) Operations Support Facility, from where the ALMA antennas will be remotely controlled. The ceremony marked the completion of the structural works, while the building itself will be finished by the end of the year. This will become the operational centre of one of the most important ground-based astronomical facilities on Earth

The ceremony, known as 'Tijerales' in Chile, is the equivalent to the 'roof-topping ceremony' that takes place worldwide, in one form or another, to celebrate reaching the highest level of a construction. It this case, the construction is the unique ALMA Operations Support Facility (OSF), located near the town of San Pedro de Atacama.

"The end of this first stage represents an historic moment for ALMA," said Hans Rykaczewski, the European ALMA Project Manager. "Once completed in December 2007, this monumental building of 7,000 square metres will be one of the largest and most important astronomical operation centres in the world." .

Cutting the red ribbon at the ALMA Operation Support Facility (OSF). In the middle, the mayor of San Pedro de Atacama, Sandra Berna, inaugurates the first stage in the construction of the OSF ALMA Building. From left to right: Carlos Cantero (senator of Chile's second region), Felix Mirabel (ESO Representative in Chile), Gabriel Vives (executive of the Chilean construction consortium VVMO) and Hans Rykaczewski (European ALMA Project Manager).

ALMA, located at an elevation of 5,000m in the Atacama Desert of northern Chile, will provide astronomers with the world's most advanced tool for exploring the Universe at millimetre and submillimetre wavelengths. ALMA will detect fainter objects and be able to produce much higher-quality images at these wavelengths than any previous telescope system.

The OSF buildings are designed to suit the requirements of this exceptional observatory in a remote, desert location. The facility, which will host about 100 people during operations, consists of three main buildings: the technical building, hosting the control centre of the observatory, the antenna assembly building, including four antenna foundations for testing and maintenance purposes, and the warehouse building, including mechanical workshops. Further secondary buildings are the transporter shelters and the vehicle maintenance facilities as well as the ALMA gate house. The construction started in August 2006 and will be completed in December 2007.

A member of the local communities near the ALMA site performs the traditional ritual of Pachamama ("Payment to the Earth"). At the back, the structure of the OSF building.

The ceremony took place in the presence of representatives of the regional authorities, members of the Chilean Parliament, and representatives of the local community, including the mayor of San Pedro, Ms. Sandra Berna, who joined more than 40 representatives of ESO, NRAO and NAOJ - the organisations that are, together, building ALMA.

"This is certainly a big step in the realisation of the ALMA Project. The completion of this facility will be essential for assembly, testing and adjustment as well as operation and maintenance of all ALMA antennas from Europe, North America and from Japan," said Ryusuke Ogasawara, the representative of NAOJ in Chile.

"This is a tremendous achievement and represents a major milestone for the ALMA project," said Adrian Russell, North American Project Manager for ALMA.

Artist's view of the ALMA OSF. All buildings are designed with a steel superstructure. Facades and roofs are made of insulated metal panels. Interior finishes for offices, laboratories and all common areas are designed to allow a comfortable working environment in this harsh location. All office and work areas have natural daylight and a splendid view of the Salar de Atacama. The buildings are covered with a 'second roof' made of louvers and designed to give maximum shade to the buildings. As such, less energy is used for the building's mechanical ventilation and air conditioning.

The first ALMA antennas, the prototypes of which successfully achieved their first combined astronomical observation last week, are expected to arrive at the ALMA site in a few months. These huge antennas will travel in pieces from Europe, USA and Japan and will be assembled next to the OSF building.

The Atacama Large Millimeter/submillimeter Array (ALMA), an international astronomy facility, is a partnership among Europe, Japan and North America, in cooperation with the Republic of Chile. ALMA is funded in Europe by the European Organisation for Astronomical Research in the Southern Hemisphere, in Japan by the National Institutes of Natural Sciences (NINS) in cooperation with the Academia Sinica in Taiwan and in North America by the U.S. National Science Foundation (NSF) in cooperation with the National Research Council of Canada (NRC). ALMA construction and operations are led on behalf of Europe by ESO, on behalf of Japan by the National Astronomical Observatory of Japan (NAOJ) and on behalf of North America by the National Radio Astronomy Observatory (NRAO), which is managed by Associated Universities, Inc. (AUI).

Source: ESO Press Release pr-13-07 Edited August 7, 2007 by Waspie_Dwarf

[Waspie_Dwarf]

Birth of a Colossus on Wheels

The European Southern Observatory (ESO) press release 32-07 is reproduced below:

ESO 32/07 - ALMA Release

30 July 2007
For Immediate Release

Birth of a Colossus on Wheels

First ALMA Transporter Ready to Go

The first of two spectacular vehicles for the ALMA (Atacama Large Millimeter/submillimeter Array) Observatory rolled out of its hangar and passed successfully a series of tests. This vehicle, the ALMA antenna transporter, is a rather exceptional 'lorry' driving on 28 tyres. It is 10m wide, 20m long and 6m high, weighs 130 tons and has as much power as two Formula 1 engines. This colossus will be able to transport a 115-ton antenna and set it down on a concrete pad within millimetres of a prescribed position.

The ALMA Project is a giant, international observatory currently in construction on the high-altitude Chajnantor site in Chile, and composed initially of 66 high-precision telescopes, operating at wavelengths of 0.3 to 9.6 mm. The ALMA antennas will be electronically combined and provide astronomical observations which are equivalent to a single large telescope of tremendous size and resolution. ALMA will be able to probe the Universe at millimetre and submillimetre wavelengths with unprecedented sensitivity and resolution, with an accuracy up to ten times better than the Hubble Space Telescope, and complementing images made with ESO's Very Large Telescope Interferometer.

Front view of the ALMA antenna transporter, a colossus on wheel that is 10 metre wide and 6 metre high. The driver's cabin was placed below the main structure to provide the driver with a good view of the wheels and help avoiding accidents.
A video is also available with this story.

The telescopes can be moved across the high-altitude desert Chajnantor plateau, covering antenna configurations as compact as 150 metres to as wide as 15 kilometres. Changing the relative positions of the antennas and thus also the configuration of the array allows for different observing modes, comparable to using a zoom lens on a camera.

"The ALMA antennas will be assembled and their functionality will be verified at a base camp, located at an altitude of 2900 metres and the transporters will in a first step bring the telescopes up to the 5000-m high observatory," explains Hans Rykaczewski, the European ALMA Project Manager. "There, the transporters will move the antennas from the compact configuration to any extended configuration which could stretch up to 15 kilometres."

"The ability to move antennas to reconfigure the observatory's array is vital to fulfilling ALMA's scientific mission. The operations plan calls for moving antennas on a regular basis to provide the flexibility that will be such a big part of ALMA's scientific value. That's why the transporters are so important and why this is such a significant milestone," says Adrian Russell, the North American Project Manager for ALMA.

Given their important functions, both for the scientific work and in transporting high-tech antennas with the required care, the vehicles must live up to very demanding operational requirements. Each transporter has a mass of 130 tons and is able to lift and transport antennas of up to a weight of 115 tons. The transporters have to position the antennas on the docking pads with precision in the millimetre range. On the other hand, the transporters must be powerful enough to reliably and safely climb from an altitude of 2900 m to 5000 m with their heavy and valuable load, putting extraordinary demands on the two 500 kW diesel engines.

Artist's rendering of an ALMA antenna being transported from the base camp to the 5000m high observing site. The transporter can move with a maximum speed of 12 km/h when loaded with a 115-ton antenna.

Not only moving telescopes to the high altitude site is a technical challenge, even driving to the base camp requires special attention. To drive this road downhill a special brake system had to be installed. Finally, as the transporters will be operated at an altitude with significantly reduced oxygen levels, a range of redundant safety devices had to be installed to protect both personnel and equipment from possible mishaps or accidents.

I says Andreas Kohler, Vice President for Research and Development at Scheuerle Fahrzeugfabrik, the company which signed in December 2005 the contract with ESO to build these two unique transporters. "The human factor was also considered. For example, the backrests of the driver seats are shaped to allow the driver to wear his oxygen tank while driving."

At the high altitude site of 5000 m, the two engines will loose about half of their power (compared to sea level) because of the reduced oxygen content on the air. The ALMA transporters will be able to move at the speed of 20 km/h when empty and 12 km/h when loaded with an antenna. The transporters can be driven from the cabin like a truck, or from a portable panel like a toy car.

The first ALMA transporter is planned to be delivered to the ALMA Observatory by the end of 2007. The second vehicle should arrive about three months later.

More Information

ALMA will be the forefront instrument for studying the cool universe - the relic radiation of the Big Bang, and the molecular gas and dust that constitute the very building blocks of stars, planetary systems, galaxies, and life itself.

Because ALMA will observe in the millimetre and submillimetre wavelengths the atmosphere above the telescope must be transparent. This requires a site that is high and dry. ALMA is thus installed at the 5000m high plateau of Chajnantor in the Atacama Desert of Chile, the world's driest area - the next best location to outer space for these high accuracy astronomical observations.

The ALMA project is a partnership between Europe, Japan and North America in cooperation with the Republic of Chile. ALMA is funded in Europe by ESO, in Japan by the National Institutes of Natural Sciences in cooperation with the Academia Sinica in Taiwan and in North America by the U.S. National Science Foundation in cooperation with the National Research Council of Canada. ALMA construction and operations are led on behalf of Europe by ESO, on behalf of Japan by the National Astronomical Observatory of Japan and on behalf of North America by the National Radio Astronomy Observatory, which is managed by Associated Universities, Inc. Scheuerle Fahrzeugfabrik GmbH is a world-leader in the design and production of custom-built heavy-duty transporters for a range of special applications.

Contact

Stefano Stanghellini
ESO, Garching, Germany
Phone: +49-89-3200-6570
Email: sstanghe (at) eso.org

Source: ESO Press Release pr-32-07 Edited August 7, 2007 by Waspie_Dwarf

[Waspie_Dwarf]

First Light for World's Largest 'Thermometer Camera'

The European Southern Observatory (ESO) press release 35-07 is reproduced below:

ESO 35/07 - Instrument Release

5 August 2007
For Immediate Release

First Light for World's Largest 'Thermometer Camera'

LABOCA in Service at APEX

The world's largest bolometer camera for submillimetre astronomy is now in service at the 12-m APEX telescope, located on the 5100m high Chajnantor plateau in the Chilean Andes. LABOCA was specifically designed for the study of extremely cold astronomical objects and, with its large field of view and very high sensitivity, will open new vistas in our knowledge of how stars form and how the first galaxies emerged from the Big Bang.

"A large fraction of all the gas in the Universe has extremely cold temperatures of around minus 250 degrees Celsius, a mere 20 degrees above absolute zero," says Karl Menten, director at the Max Planck Institute for Radioastronomy (MPIfR) in Bonn, Germany, that built LABOCA. "Studying these cold clouds requires looking at the light they radiate in the submillimetre range, with very sophisticated detectors."

The LABOCA Camera installed on the APEX telescope at the 5100m high Chajnantor site in Chile. LABOCA is a 'thermometer camera' with 295 detectors and a field of view of 11.4 arcmin.

Astronomers use bolometers for this task, which are, in essence, thermometers. They detect incoming radiation by registering the resulting rise in temperature. More specifically, a bolometer detector consists of an extremely thin foil that absorbs the incoming light. Any change of the radiation's intensity results in a slight change in temperature of the foil, which can then be registered by sensitive electronic thermometers. To be able to measure such minute temperature fluctuations requires the bolometers to be cooled down to less than 0.3 degrees above absolute zero, that is below minus 272.85 degrees Celsius.

"Cooling to such low temperatures requires using liquid helium, which is no simple feat for an observatory located at 5100m altitude," says Carlos De Breuck, the APEX instrument scientist at ESO.

Nor is it simple to measure the weak temperature radiation of astronomical objects. Millimetre and submillimetre radiation opens a window into the enigmatic cold Universe, but the signals from space are heavily absorbed by water vapour in the Earth's atmosphere. "It is a bit as if you were trying to see stars during the day," explains Axel Weiss of the MPIfR and leader of the team that installed LABOCA on APEX.

Comparison between an image of the Galactic HII region RCW 120 in the visible (R-band; as obtained by the ESO Schmidt Telescope) and in the submillimetre with LABOCA on APEX, highlighting the need to observe in this wavelength range. The LABOCA image has an exposure of only slightly more than 3 hours. The expanding shell causes the surrounding gas to collapse into clumps, which are the cradles of massive stars. As the gas in these clumps is still very cold, around -250 degrees Celsius, they can only be seen at submillimetre wavelengths. Thanks to the high sensitivity and large field of view of LABOCA, astronomers could detect clumps that are four times fainter than was possible before. As the brightness is also a measure of the mass of these stellar embryos, this will allow scientists to study the formation of more representative, less massive stars.

This is why telescopes for this kind of astronomy must be built on high, dry sites, and why the 5100m high plateau at Chajnantor in the extremely dry Atacama Desert was chosen. Even under such optimal conditions the heat from Earth's atmosphere is still a hundred thousand times more intense than the tiny astronomical signals from distant galaxies. Very special software is required to filter such weak signals from the overwhelming disturbances.

LABOCA (LArge BOlometer Camera) and its associated software were developed by MPIfR. "Since so far there are no commercial applications for such instruments we have to develop them ourselves," explains Ernst Kreysa, from MPIfR and head of the group that built the new instrument.

A bolometer camera combines many tiny bolometer units into a matrix, much like the pixels are combined in a digital camera. LABOCA observes at the submillimetric wavelength of 0.87 mm, and consists of 295 channels, which are arranged in 9 concentric hexagons around a central channel. The angular resolution is 18.6 arcsec, and the total field of view is 11.4 arcmin, a remarkable size for instruments of this kind.

"The first astronomical observations with LABOCA have revealed its great potential. In particular, the large number of LABOCA's detectors is an enormous improvement over earlier instruments," says Giorgio Siringo from MPIfR and member of the LABOCA team. "LABOCA is the first camera that will allow us to map large areas on the sky with high sensitivity."

The Atacama Pathfinder Experiment (APEX) where LABOCA is installed is a new-technology 12-m telescope, based on an ALMA prototype antenna, and operating at the ALMA site. It has modified optics and an improved antenna surface accuracy, and is designed to take advantage of the excellent sky transparency working with wavelengths in the 0.2 to 1.4 mm range.

"APEX is located a mere 2 km from the centre of the future ALMA array. The new LABOCA camera will be very complementary to ALMA, as its very wide view will find thousands of galaxies which will be observed in great detail with ALMA," says De Breuck.

APEX is a collaboration between the Max Planck Institute for Radioastronomy, Onsala Space Observatory and ESO.

Contact

Carlos De Breuck
ESO, Garching, Germany
Phone: +49 89 3200 6613
Email: cdebreuc (at) eso.org

Karl Menten
Max-Planck-Institut für Radioastronomie
Bonn, Germany
Phone: +49 228 525 297
Email: kmenten (at) mpifr-bonn.mpg.de


Source: ESO Press Release pr-35-07

[Waspie_Dwarf]

A Colossus Gets its Name

The European Southern Observatory (ESO) press release 45-07 is reproduced below:

ESO 45/07 - ALMA Release

5 October 2007
For Immediate Release

A Colossus Gets its Name

ALMA Antenna Transporter Presentation

Today, the first of the two ALMA antenna transporters was given its name at a ceremony on the compounds of the manufacturer, the heavy-vehicle specialist Scheuerle Fahrzeugfabrik GmbH, in Baden-Württemberg. The colossus, 10 metres wide, 20 metres long and 6 metres high, will be shipped to Chile by the end of the month. The second one will follow in a few weeks.

The transporter was named 'Otto' in honour of Otto Rettenmaier, the owner of the Scheuerle company. "The rather unusual move to name a vehicle is a recognition of the remarkable achievement these unique machines represent," said Hans Rykaczewski, the European ALMA Project Manager. "Their sizes alone would justify using superlatives to describe them. But they are also outstanding as they will operate at 5000 metres altitude, where the air is rare, and they have to be able to place 115-ton antennas with a precision of a few millimetres," he added.

"The ALMA antenna transporters are the proof of the excellence of our staff and of our ability to build heavy vehicles that are at the limits of the possible," said Otto Rettenmaier. "Never in the history of our company have we had to comply with such exceptional requirements on material and techniques as we had to do with these machines. We are proud as a company to have been able to contribute with such an exceptional piece of technology for astronomical research."

The first of the two 130-ton ALMA antenna transporters was named 'Otto' on 5 October 2007 to highlight the remarkable achievement these unique machines represent. These vehicles will operate at 5000 metres altitude, where the air is rare, and they are able to place 115-ton antennas with a precision of a few millimetres.

The ALMA Project, in which ESO leads the construction and the operations on behalf of Europe, is a giant, international observatory currently in construction on the high-altitude Chajnantor site in Chile, which will be composed initially of 66 high-precision telescopes, operating at wavelengths of 0.3 to 9.6 mm. The ALMA antennas will be electronically combined and provide astronomical observations which are equivalent to a single large telescope of tremendous size and resolution.

The 66 antennas of the array can be placed on 192 different pads, covering antenna configurations as compact as 150 metres to as wide as 15 kilometres. Changing the relative positions of the antennas and thus also the configuration of the array allows for different observing modes, comparable to using a zoom lens on a camera.

Given their important functions, both for the scientific work and in transporting high-tech antennas with the required care, the vehicles must live up to very demanding operational requirements. To address these, Scheuerle has developed and built two very special transporters. Building heavy vehicles able to transport with great precision 115-ton antennas is not a problem per se for this company, which specialises in building huge transporters. The problem however was to produce a vehicle able to operate at such a high altitude, where the two engines will lose about half of their power (compared to sea level) because of the reduced oxygen content of the air. With their two 500 kW diesel engines (nearly as much as two Formula 1 engines), the ALMA transporters will be able to move at the speed of 20 km/h when empty and 12 km/h when loaded with an antenna.

Notwithstanding its impressive dimensions, the transporter can be manoeuvred by a single operator, the precise positioning being made possible by a hydrostatic system while the electronic 28-wheel drive allows very precise motions.

"When completed in 2012, ALMA will be the largest and most capable imaging array of telescopes in the world," said Massimo Tarenghi, the ALMA Director. "The ALMA antenna transporters, which are unique technological jewels, beautifully illustrate how we are actively progressing towards this goal."

More Information

ALMA will be able to probe the Universe at millimetre and submillimetre wavelengths with unprecedented sensitivity and resolution, with an accuracy up to ten times better than the Hubble Space Telescope, and complementing images made with ESO's Very Large Telescope Interferometer.

ALMA will be the forefront instrument for studying the cool universe - the relic radiation of the Big Bang, and the molecular gas and dust that constitute the very building blocks of stars, planetary systems, galaxies, and life itself.

Because ALMA will observe in the millimetre and submillimetre wavelengths the atmosphere above the telescope must be transparent. This requires a site that is high and dry. ALMA will thus be installed at the 5000m high plateau of Chajnantor in the Atacama Desert of Chile, the world's driest area - the next best location to outer space for these high-accuracy astronomical observations.

The ALMA project is a partnership between Europe, East Asia and North America in cooperation with the Republic of Chile. ALMA is funded in Europe by ESO, in East Asia by the National Institutes of Natural Sciences of Japan in cooperation with the Academia Sinica in Taiwan and in North America by the U.S. National Science Foundation in cooperation with the National Research Council of Canada. ALMA construction and operations are led on behalf of Europe by ESO, on behalf of East Asia by the National Astronomical Observatory of Japan and on behalf of North America by the National Radio Astronomy Observatory, which is managed by Associated Universities, Inc.

Contact

Stefano Stanghellini
ESO, Garching, Germany
E-mail: sstanghe (at) eso.org
Phone: +49-89-3200-6570

Source: ESO Press Release pr-45-07