National Radio Astronomy Observatory
520 Edgemont Road
Charlottesville, VA 22903


Rebecca Johnson, NRAO Public Information Officer
Charlottesville, VA
(804) 296-0323

Dave Finley, NRAO Public Information Officer
Socorro, NM
(505) 835-7302

Richard West, ESO Public Information Officer
Garching, Germany
+49 89 32006276

The U.S. and European partners in the Atacama Large Millimeter Array
(ALMA) project have awarded contracts to U.S. and Italian firms,
respectively, for two prototype antennas. ALMA is a planned telescope
array, expected to consist of 64 millimeter-wave antennas with 12-meter
diameter dishes. The array will be built at a high-altitude, extremely
dry mountain site in Chile’s Atacama desert, and is scheduled to be
completed sometime in this decade.

On February 22, 2000, Associated Universities Inc. (AUI) signed an
approximately $6.2 million contract with Vertex Antenna Systems, of
Santa Clara, Calif., for construction of one prototype ALMA antenna.
AUI operates the U.S. National Radio Astronomy Observatory (NRAO) for
the National Science Foundation under a cooperative agreement. The
European partners contracted with the consortium of European Industrial
Engineering and Costamasnaga, of Mestre, Italy, on February 21, 2000,
for the production of another prototype. (Mestre is located on the
inland side of Venice.) The two antennas must meet identical
specifications, but will inherently be of different designs. This will
ensure that the best possible technologies are incorporated into the
final production antennas. Only one of the designs will be selected for
final production.

Several technical challenges must be met for the antennas to perform to
ALMA specifications. Each antenna must have extremely high surface
accuracy (25 micrometers, or one-third the diameter of a human hair,
over the entire 12-meter diameter). This means that, when completed, the
surface accuracy of the ALMA dishes will be 20 times greater than that
of the Very Large Array (VLA) antennas, and about 50 times greater than
dish antennas for communications or radar. The ALMA antennas must also
have extremely high pointing accuracy (0.6 arcseconds).

An additional challenge is that the antennas, when installed at the ALMA
site in Chile, will be exposed to the ravages of weather at 16,500 feet
(5000 meters) elevation. All previous millimeter-wavelength antennas
that meet such exacting specifications for surface accuracy and pointing
accuracy have been housed within telescope enclosures.

The U.S. and European prototype antennas will be delivered to the NRAO VLA
site, near Socorro, New Mexico, in October and November of 2001,
respectively. Preparations for ALMA prototype testing are already underway
at the VLA site. Three pads are being constructed for the antennas to rest
on. An ALMA control room within the VLA control building is being
established. About ten full-time ALMA staff will be involved in the
testing. Additionally, ALMA project members from around the U.S. and the
world will visit the VLA site to participate in the test program. The two
prototype antennas will first be tested separately. Following that, the two
will be linked together and tested as an interferometer.

Millimeter-wave astronomy is the study of the universe in the spectral
region between what is traditionally considered radio waves and infrared
radiation. In this realm, ALMA will study the structure of the early
universe and the evolution of galaxies; gather crucial data on the
formation of stars, protoplanetary disks, and planets; and provide new
insights on the familiar objects of our own solar system.

ALMA is an international partnership between the United States (National
Science Foundation) and Europe. European participants include the member
states of the European Southern Observatory (Belgium, Denmark, France,
Germany, Italy, the Netherlands, Sweden and Switzerland), the Centre
National de la Recherche Scientifique (France), the Max-Planck
Gesellschaft (Germany), the Netherlands Foundation for Research in
Astronomy, the United Kingdom Particle Physics and Astronomy
Research Council, the Oficina de Ciencia Y Tecnologia/Instituto Geografico
Nacional OCYT/IGN (Spain), and the Swedish Natural Science Research Council

The project is currently in a Design and Development phase governed by a
Memorandum of Understanding between the United States and Europe. It is
hoped and expected that Japan will also join the project as a third
equal partner. Negotiations are currently underway to add Canada to the
United States team and Spain to the European team.

The National Radio Astronomy Observatory is a facility of the National
Science Foundation, operated under cooperative agreement by
Associated Universities, Inc.