ALMA Site Information

The ALMA Array Operations Site (AOS) will be located at the Altiplano de Chajnantor, a plateau at an altitude of 5000 metres in the Atacama Desert in Chile. Of course, this location was selected because of many well justified scientific reasons, particularly dryness and altitude. Considering these aspects, the ALMA Observatory will not only be unique because of its ambitious scientific goals, and the unprecedented technical requirements, it will also be unique because of the very specific, harsh environment and living conditions in which the most challenging radio telescope array will operate with high efficiency and accuracy.

The ALMA Observatory will be operated at two distinct sites, far away from comfortable living conditions of modern civilization. The ALMA Operations Support Facilities (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. The OSF will also serve as 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.

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. The OSF site 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. This road, 43 km in length, has sufficient width to regularly transport a large number of 12meter radio telescopes.

The Operations Support Facilities (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 and AIVC activities. AIVC 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.

8 MWatt Power Demand in the Desert at high Altitude

Supplying energy for an observatory at altitudes of 2900 metres and 5000 metres in the Chilean desert of Atacama is not at all trivial. During the last few years energy supply and prices have rapidly and drastically changed.In view of these developments on the energy market, ALMA decided to move toward using electricity provided by Northern Chilean electricity suppliers. This scheme requires the erection and operation of an overhead power line from the best suited electricity generator to the OSF and AOS.

An Observatory Located at an Altitude Higher than Europe's Highest Summit

The construction of the AOS Technical Building, a project to be delivered by the North American partner in ALMA, started in October 2005. Operations at the AOS will, because of the harsh environment, be limited to an absolute minimum. 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.

Respecting Culture and Nature

Although it is one of the most ambitious high-technology scientific projects, activities on the ALMA site not only focus on building the world's most advanced and challenging astronomical ground-based observatory. Historical and environmental aspects in this unique region are of concern. The remains of a small local settlement located along the access road at km 21 have been rebuilt taking into account the advice of the last owner and after consulting an archaeologist from San Pedro. The place serves now as a museum and an interpretive centre for local cultures and history. Wildlife in these altitudes is protected. Colonies of Vizcachas, a local species of rodents, were identified along the ALMA-AOS access road at km 30. Local Chilean Authorities are carefully monitoring the movements of these colonies. The goal is that ALMA Site construction will not disturb wildlife.