Astronomers Break Ground on Atacama Large Millimeter Array (Forwarded)

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Embargoed until November 6, 2003, at 16:30 hrs CET
(15:30 hrs UT - 12:30 hrs Chilean Time - 10:30 a.m. EST)

ESO Press Release 29/03

Astronomers Break Ground on Atacama Large Millimeter Array
(ALMA) -- World's Largest Millimeter Wavelength Telescope [1]

Scientists and dignitaries from Europe, North America and Chile
are breaking ground today (Thursday, November 6, 2003) 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.

The Atacama Large Millimeter Array (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.

Science with ALMA

ALMA will capture millimetre and sub-millimetre radiation from
space and produce images and spectra of celestial objects as
they appear at these wavelengths. This particular portion of
the electromagnetic spectrum, which is less energetic than
visible and infrared light, yet more energetic than most radio
waves, holds the key to understanding a great variety of
fundamental processes, e.g., planet and star formation and the
formation and evolution of galaxies and galaxy clusters in the
early Universe. The possibility to detect emission from organic
and other molecules in space is of particularly high interest.

The millimetre and sub-millimetre radiation that ALMA will
study is able to penetrate the vast clouds of dust and gas
that populate interstellar (and intergalactic) space, revealing
previously hidden details about astronomical objects. This
radiation, however, is blocked by atmospheric moisture (water
molecules) in the Earth's atmosphere. To conduct research with
ALMA in this critical portion of the spectrum, astronomers
thus need an exceptional observation site that is very dry,
and at a very high altitude where the atmosphere above is
thinner. Extensive tests showed that the sky above the
high-altitude Chajnantor plain in the Atacama Desert has
the unsurpassed clarity and stability needed to perform
efficient observations with ALMA.

ALMA operation

ALMA will be the highest-altitude, full-time ground-based
observatory in the world, at some 250 metres higher than the
peak of Mont Blanc, Europe's tallest mountain.

Work at this altitude is difficult. To help ensure the safety
of the scientists and engineers at ALMA, operations will be
conducted from the Operations Support Facility (ALMA OSF), a
compound located at a more comfortable altitude of 2,900
metres, between the cities of Toconao and San Pedro de Atacama.

Phase 1 of the ALMA Project, which included the design and
development, was completed in 2002. The beginning of Phase 2
happened on February 25, 2003, when the European Southern
Observatory (ESO) and the US National Science Foundation (NSF)
signed a historic agreement to construct and operate ALMA,
cf. ESO PR 04/03.

Construction will continue until 2012; however, initial
scientific observations are planned already from 2007, with a
partial array of the first antennas. ALMA's operation will
progressively increase until 2012 with the installation of
the remaining antennas. The entire project will cost
approximately 600 million Euros.

Earlier this year, the ALMA Board selected Professor Massimo
Tarenghi, formerly manager of ESO's VLT Project, to become
ALMA Director. He is confident that he and his team will
succeed: "We may have a lot of hard work in front of us", he
said, "but all of us in the team are excited about this
unique project. We are ready to work for the international
astronomical community and to provide them in due time with
an outstanding instrument allowing trailblazing research
projects in many different fields of modern astrophysics".

How ALMA will work

ALMA will be composed of 64 high-precision antennas, each 12
metres in diameter. The ALMA antennas can be repositioned,
allowing the telescope to function much like the zoom lens on
a camera. At its largest, ALMA will be 14 kilometers across.
This will allow the telescope to observe fine-scale details
of astronomical objects. At its smallest configuration,
approximately 150 meters across, ALMA will be able to study
the large-scale structures of these same objects.

ALMA will function as an interferometer (according to the same
basic principle as the VLT Interferometer (VLTI) at Paranal).
This means that it will combine the signals from all its
antennas (one pair of antennas at a time) to simulate a
telescope the size of the distance between the antennas.

With 64 antennas, ALMA will generate 2016 individual antenna
pairs ("baselines") during the observations. To handle this
enormous amount of data, ALMA will rely on a very powerful,
specialized computer (a "correlator"), which will perform
16,000 million million (1.6 x 10**16) operations per second.

Currently, two prototype ALMA antennas are undergoing rigorous
testing at the NRAO's Very Large Array site, near Socorro, New
Mexico, USA.

International collaboration

For this ambitious project, ALMA has become a joint effort among
many nations and scientific institutions. In Europe, ESO leads
on behalf of its ten member countries (Belgium, Denmark, France,
Germany, Italy, The Netherlands, Portugal, Sweden, Switzerland
and the United Kingdom) and Spain. Japan may join in 2004,
bringing enhancements to the project. Given the participation
of North America, this will be the first truly global project
of ground-based astronomy, an essential development in view of
the increasing technological sophistication and the high costs
of front-line astronomy installations.

The first submillimeter telescope in the southern hemisphere
was the 15-m Swedish-ESO Submillimetre Telescope (SEST) which
was installed at the ESO La Silla Observatory in 1987. It has
since been used extensively by astronomers, mostly from ESO's
member states. SEST has now been decommissioned and a new
submillimetre telescope, APEX, is about to commence operations
at Chajnantor. APEX, which is a joint project between ESO, the
Max Planck Institute for Radio Astronomy in Bonn (Germany),
and the Onsala Space Observatory (Sweden), is an antenna
comparable to the ALMA antennas.

Note

[1]: This ESO Press Release is being co-ordinated with the
National Radio Astronomy Observatory (NRAO) in the USA, and
with the ALMA Office in Chile.

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