ALMA, the biggest radiotelescope in the world, has been officially inaugurated

Some ALMA antennae (Photo ESO/C. Malin)
Some ALMA antennae (Photo ESO/C. Malin)

Yesterday the Atacama Large Millimeter / submillimeter Array (ALMA), was officially inaugurated. It’s an astronomical radiointerferometro built in the Atacama Desert in northern Chile, composed of 66 antennas of 12 and 7 meters that can observe at millimeter and sub-millimeter wavelengths. The purpose of ALMA is to study the birth of stars and planets, even in the early universe.

The ALMA project was born from three different projects: the American Millimeter Array (MMA), the European Large Southern Array (LSA) and the Japanese Large Millimeter Array (LMA). The original agreement was signed in 1997 between the European Southern Obseravatory (ESO) and the National Radio Astronomy Observation (NRAO) to join MMA and LSA taking their best features.

The first project, which of course also included Chile, was called Atacama Large Array Millimiter but in later years Canada, Spain and Japan joined it and in 2004 the agreement to establish was reached to create a more powerful array that could also be observed sub-millimeter wavelengths, from which the final name.

Astronomical observatories, and even more sensitive arrays such as ALMA, need optimal conditions such as altitude and stable weather conditions to minimize the interference caused by the atmosphere, they must be far away from cities to avoid light pollution but of course they need roads for logistic connections. The Atacama desert is probably the driest place in the world and is virtually sterile and the plateau of Chajnantor is about 5,000 meters (about 16,500 feet) above sea level, ideal conditions.

On the contrary, the conditions for the transport of the 115-ton antennas that compose the array are terrible. Two 24-wheel vehicles with 500 KW engines were built specifically for this task. The drivers had at their disposal an oxygen tank to be able to breathe once they reached high altitudes.

To manage the antenna array one of the most powerful supercomputers in the world was built. Its computing power is close to that of Titan, the current title holder as the world’s most powerful, but the ranking includes only general purpose computers while the ALMA one has a special purpose.

In summer 2011 enough antennas were installed to start testing ALMA and in autumn 2011 the array became officially operational, though at reduced power. In the following months several observations were made such as those of the systems of the stars Fomalhaut and HD 142527.

The inauguration that took place yesterday, with Chile’s President Sebastián Piñera as the guest of honor, marks the transition to the stage of full operation for ALMA. Some targets for the observations have already been identified, others will be determined, in all cases we can expect more discoveries.

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