ALMA Correlator Supercomputer Turns Man Antennas Into One Giant Telescope
December 21, 2012

Building The World’s Highest-altitude Supercomputer

[ Watch the Video: All Systems Go for Highest Altitude Supercomputer ]

Michael Harper for — Your Universe Online

When one begins to search for the origins of the universe, it helps to be well-equipped and as close to the heavens as possible. Therefore, the Atacama Large Millimeter/sub-millimeter Array (or ALMA) has been built high up in the martian-esque landscape of the Atacama desert of northern Chile. Each of these 66 radio telescopes (or giant antennas) are used in harmony to collect and measure wavelengths of light in order to understand how stars and planets are born. From there, the international partnership between Chile, East Asia, Europe and the US hope to draw conclusions as to how our own little planet was born.

To turn this raw data into images, the ALMA team will now turn to a new supercomputer which has just been installed at the facility with the help of the European Southern Observatory (ESO).

Known simply as the correlator, this new supercomputer is capable of performing in-step with some of the world´s fastest supercomputers, crunching as many as 17 quadrillion calculations a second, or 17 petaflops. There are 134 million processors housed within the correlator that will work to stitch together all the information received from each radio telescope in the ALMA array. According to Wolfgang Wild, the ALMA project manager for the ESO, while it was important to build a fast and cutting edge computer, the correlator was built to address the specific needs of the ALMA project.

“This unique computing challenge needed innovative design, both for the individual components and the overall architecture of the correlator,” said Wild in a press statement.

Scanning the heavens for the origins of the universe is a team effort. As such, building the correlator also took some collaboration between the US teams and the European teams. This new astronomically minded super computer was initially designed, constructed and installed by the US National Radio Astronomy Observatory (NRAO). The correlator has been funded by the US National Science Foundation as well as the ESO. A prime component of the new correlator was supplied exclusively by the ESO, however, and has been integrated into the initial NRAO design.

A set of 550 digital filter circuit boards have been designed and built for the ESO by the University of Bordeaux in France. These filters help the ALMA array to hone in on specific wavelengths in the light, resulting in a clearer image.

“This vastly improved flexibility is fantastic; it lets us ℠slice and dice´ the spectrum of light that ALMA sees, so we can concentrate on the precise wavelengths needed for a given observation, whether it´s mapping the gas molecules in a star-forming cloud, or searching for some of the most distant galaxies in the Universe,” explained Alain Baudry, the correlator team leader from the University of Bordeaux.

The high altitude of the ALMA site presented some challenges to the correlator team. For instance, the ALMA Operations Site is the highest technical building in the world. At more than 16,000 feet, twice the amount of air is needed to cool the correlator supercomputer. The correlator also had to be designed to work without spinning disk drives, as the thin air at this altitude could cause traditional drives to fail. The Atacama desert is also prone to “seismic activity”: Another issue the ALMA team had to take into consideration when building the correlator supercomputer.

ALMA began looking to the sky in 2011 with only a portion of their total array antennas. With the correlator built and ready to be put to service, the ALMA group hopes to be fully operational and inaugurated in March 2013.