Published: Tue 14 Dec 2010. Modified: Tue 11 Jan 2011

Swedish receiver to hunt for cosmic water in Chile

PRESS RELEASE: The world's most sensitive receiver for radio waves with wavelength around 1.5 millimetres has been delivered from Chalmers to the international ALMA Observatory in northern Chile.

When it reaches its final destination, 5000 metres above sea level, the receiver will allow scientists to trace water in the nearby universe. It will also provide an unprecedented view of the most distant galaxies. The delivery is a milestone for an EU-financed project which has developed new technologies from scratch in just five years.

ALMA, an international astronomy facility now being built in northern Chile, is a partnership of Europe, North America and East Asia in cooperation with the Republic of Chile. The observatory will be used to study the youngest and most distant galaxies in the universe, and to see into areas where layers of cosmic dust otherwise prevent astronomers from studying the birthplaces of stars and planets. To do this ALMA observes in light with wavelength of around one millimeter. Such light is invisible to our eyes and lies between infrared light and radio waves in the electromagnetic spectrum.

A group of scientists at Chalmers and Onsala Space Observatory have constructed a new, advanced receiver built to detect radio waves with wavelengths between 1.4 and 1.8 millimetres (frequencies between 163 and 211 gigahertz; known as ALMA Band 5). The Swedish receiver will be an important part of future instrumentation for the ALMA Observatory (the Atacama Large Millimeter/submillimeter Array), an array of 66 giant antennas in the Atacama Desert, Chile.

 “Our group is one of only six teams in the world who have received contracts to produce receivers for ALMA. Onsala Space Observatory and Chalmers have played a key role in developing technology that will lead to important discoveries about our cosmic origins”, says Hans Olofsson, professor of astronomy at Chalmers University and director of Onsala Space Observatory.

The receiver takes advantage of the exceptionally dry air at the ALMA site to observe the radiation emitted by water molecules in our galaxy and beyond, something which has until now been the preserve of space telescopes. With Chalmers' receivers in place, ALMA will be able to make sharper images than ever before of cosmic water. In addition to its importance for life, water also plays a major role in the formation of stars and planetary systems.

"This receiver is the most advanced currently available in its frequency range. Deployed on ALMA at 5000 m altitude, it will open a new window on the universe, enabling high-resolution imaging of water in our Galaxy and the formation of the very first galaxies", says Robert Laing, project scientist for ALMA instrumentation at the European Southern Observatory (ESO), the European partner in the global ALMA project.

The delivery marks the end of a challenging but quickly implemented development project for Onsala Space Observatory’s Advanced Receiver Development group, based at Chalmers University of Technology in Göteborg, Sweden. The project was funded by the European Commission's Sixth Framework Programme for Research and Technological Development. Chalmers’ Advanced Receiver Development has previously developed receivers for the APEX telescope in Chile, the 20-meter telescope at Onsala in Sweden and the Odin satellite.

Victor Belitsky, professor of advanced receiver development at Chalmers, who led the work, explains that advanced nanoelectronics are needed to detect radio waves and to minimize background noise from the receiver itself.

“We have achieved the highest receiver sensitivity by using superconducting electronic components, tunnel junctions, which are cooled to four degrees above absolute zero in order to take advantage of the material’s quantum properties”, says Victor Belitsky.

The group has now delivered the receiver to the ALMA European Front End Integration Centre operated by the STFC's Rutherford Appleton Laboratory, UK. There it will be tested together with the other instrumentation. In April 2011 it will be transferred to the Chajnantor plateau in northern Chile, where it later will be joined by five identical receivers, now under construction at Chalmers. An international consortium has been formed to ensure that receivers can be produced for all the antennas in the complete ALMA observatory.


TEXT: Robert Cumming
PHOTOS: ALMA (ESO/NAOJ/NRAO)/L. Calçada (ESO)  and Onsala Space Observatory/B. Billade

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Published: Tue 14 Dec 2010. Modified: Tue 11 Jan 2011