November 21, 2012
North American ALMA Antenna Dishes Finished And Delivered
April Flowers for redOrbit.com - Your Universe Online
It has taken more than a decade of design and construction, but North America has finally delivered the last of 25 antenna dishes, marking an important milestone in the construction of an observatory astronomers are using to open up a "final frontier" of the spectrum of visible light to exploration. The dishes are 12-meters in diameter, and comprise the North American share of antennas for the international ALMA telescope.
Stretching across more than 75 miles of high altitude desert plain in Chile, ALMA — the Atacama Large Millimeter/submillimeter Array — is an international project built and funded by scientific communities in North America, Europe and East Asia. At $1.3 billion dollars, ALMA will have 66 antennas when completed — 25 from North America, 25 from Europe and 16 from East Asia.
"We are delighted to deliver this final ALMA antenna from North America," said Mark McKinnon, the North American ALMA Project Director at the National Radio Astronomy Observatory (NRAO) in Charlottesville, Virginia. "It is a real testimony to the production team that we were able to overcome many technical challenges to complete the antenna delivery."
Gas and dust in space emit faint radio waves naturally, and these will be detected and measured by the antennas. A supercomputer will then process the measurements to generate images as detailed as would come from a single dish that was miles in diameter. Astronomers will gain insights into previously invisible or unresolved processes of planet, star and galaxy evolution both nearby and across cosmic time.
Scientists have been using this technique of combining radio telescopes to form a virtual, high resolution instrument for decades. The National Science Foundation's (NSF) Very Large Array (VLA) in New Mexico is a prime example, as it uses the same technique to explore the Universe as seen in centimeter-wavelength light.
ALMA moves a step beyond, however. It is the first VLA-scale array to attempt this feat at millimeter and submillimeter wavelengths. To work with such short wavelengths, the antenna dish surface must be more precise and able to maintain its parabolic curvature to within the thickness of a human hair amidst harsh conditions at the 16,500-foot high ALMA site.
The NSF provided funding to build the North American antennas in the single largest procurement in the history of the foundation's astronomy division. The antennas were manufactured and assembled by General Dynamics SATCOM Technologies, integration and testing was overseen by NRAO, and Associated Universities, Inc. (AUI) managed the contract. General Dynamics also built the hanger building on site in Chile where each antenna's pedestal and dish structure components were shipped separately and assembled.
ALMA is expected to serve as a state-of-the-art radio telescope for 30 years or more, once it is completed next year.
"This is a very exciting time in astronomy," commented Tony Beasley, NRAO Director. "With ALMA we are taking perhaps the greatest leap in observing power in the history of the science."
"ALMA is the largest, most expensive ground-based astronomy project ever attempted, and a model for international science collaborations. The success of the partnership is manifest in the achievement of this milestone, but will be even more evident in the legacy of discovery and understanding that is going to emerge over the coming years, as tomorrow's eager astronomers get their hands on this fantastic telescope," said Ethan Schreier, president of AUI.