|
The ”soul of space” lies in the Chilean desert. Here at an altitude of 5 000 m above sea level ALMA (the abbreviation for Atacama Large Millimeter Array, and also the Spanish word for ”soul”), the highest sub-millimeter observatory in the world, is being built. The huge telescope, an international project which was started in 1999 by ESO (European Southern Observatory) and the American NRAO (National Radio Astronomy Observatory), will depict the universe in the range of dwarf waves in sharper focus than has ever been achieved before and thus provide new insights into the formation of stars, planets and galaxies. The Chajnantor Plateau, which has an extremely thin and dry atmospheric layer, offers excellent conditions for astronomical research.
A total of 64 antennas, each 12 m in diameter, will be installed on an area of 7 000 m². To this end three antenna prototypes will first be tested. The US prototype was put into operation on the ALMA test site in New Mexico at the beginning of November and the European and Japanese antennas are to follow in spring 2003. The test results will then decide which type is used.
The US version was designed and built by VERTEX Antennentechnik (Duisburg, Germany) for VertexRSI in Santa Clara, California. The various system parts of the antenna were delivered from all over the world. In the harsh Chilean desert climate with temperatures ranging from – 40°C to + 20°C, extreme fluctuations in temperature, intense UV radiation, winds and storms, it is important that the receiver cabin is adequately air-conditioned and kept at the correct temperature. It is essential that conditions in the room remain constant, in order to ensure, as far as possible, that the antenna mirror is not distorted by even a micrometer. The parts for the air-conditioning and ventilation systems were supplied by MENERGA Apparatebau (Mülheim an der Ruhr, Germany). MENERGA used the high-temperature insulation material HT/Armaflex to insulate the brine pipes. The UV-resistant product is suitable for the temperature range + 150° C to - 50° C. Short-term temperatures of up to +175° C are possible. With a resistance to water vapor transmission of µ > 3000, the highly flexible insulation material provides very good protection against the ingress of water vapor while at the same time having a very low thermal conductivity value (0 = 0,040 W/(m · K).
HT/Armaflex was also used in a modified copy of the VERTEX antenna. This was commissioned by the German Max-Planck-Institute and is being installed in the preliminary phases of the ALMA observatory project on the Chilean plateau.
|