AOS and OSF Sites

A world-class observatory in the desert!

The ALMA Observatory will be operated at two distinct sites, far away from comfortable living conditions of modern civilization.

The ALMA Operations Support Facility (OSF) will be the base camp for the every-day, routine operation of the observatory.

It is located at an altitude of about 2900 metres, quite high compared to standard living conditions, but still quite acceptable for scientific projects in astronomy of similar scope. However, the OSF will not only serve as the location for operating the Joint ALMA Observatory, it is also the Assembly, Integration, Verification, and Commissioning (AIVC) station for all the high technology equipment before being moved to the Array Operations Site (AOS), located at 5000 metres altitude.

The Operations Support Facility (OSF)

The OSF is and will continue to be, in many aspects, the centre of activities of the ALMA project. Focus of the activities will change as ALMA achieves several and quite different objectives of the entire project.  Presently it is the area where all ALMA Site contractors and their staff are accommodated. Special camps have been erected and by now can accommodate the maximum required capacity of 500 workers.

The OSF, of course, does not only serve as the base camp for contractors. It will become the focal point of all antenna Assembly-Integration-Verification (AIV) activities. Antenna assembly is done at the OSF site at three separate areas, one each for the antennas provided by North America (VERTEX), Japan (MELCO), and Europe (AEM Consortium). AIV activities will be carried out at the OSF, after preliminary acceptance of the antennas, and prior to moving them to the AOS.

Ultimately, the OSF and its Technical Facilities will become the centre of all scientific activities related to the daily operation of the Joint ALMA Observatory. The OSF will be the central location for running the observatory and taking care of all maintenance and operations aspects. During the operations phase of the observatory it will be the workplace of the astronomers and of the teams responsible for maintaining proper functioning of all the telescopes. The quality of all ALMA data will be assessed at the OSF. 

The Array Operations Site (AOS): The second highest building in the world

The construction of the AOS Technical Building started in October 2005 and the outer shell was completed by mid 2006. Inside construction work was completed in summer 2007. Human operations at the AOS will be limited to an absolute minimum, due to the high altitude. The AOS Technical Building will house the receiving end of the Back End and the Correlator . Digitized signals received from the radio telescopes are processed here and further transmitted to the data storage facilities located at the OSF.

 

A High Altitude Road with Super-Highway Dimensions

The construction of the OSF and AOS sites and their access required substantial efforts of the ALMA project. Obviously, there was no access to these two remote locations (see Figure below). The OSF site, located at 2900 metres altitude, is about 15 kilometers away from the closest public road, the Chilean highway No. 23. The AOS is another 28 kilometers away from the OSF site. Thus, one of the first projects to be accomplished by ALMA was to construct an access road not only to the OSF but also to the AOS – a road, 43 km in length, not only at high altitudes, but also with sufficient width to regularly transport a large number of large radio telescopes with a diameter of 12 metres.