ALMA observatory has its sights set on the universe

The Atacama Large Millimetre/Submillimetre Array (ALMA) is ready to start early science observations.

At present, around a third of ALMA’s eventual 66 radio antennas, with separations up to only 125m rather than the maximum 16km, make up the growing array on the Chajnantor plateau in northern Chile, at an elevation of 5,000m.

When it is completed in 2013, scientists will have an 11-mile-wide array of ultra-precision millimetre/submillimetre wave radio telescopes working together as one.

Scientists will use the observatory to study portions of the universe at a level of detail that is beyond what current astronomical technologies provide, studying the origins of galaxies, stars, and planets.

‘The “M” in ALMA stands for “millimetre/submillimetre” waves, because ALMA views the universe in these long wavelengths of light, much longer than the optical light we see with our eyes,’ said Dr Alison Peck, an NRAO astronomer serving as ALMA deputy project scientist during construction.

‘With millimetre and submillimetre waves, we can watch planet formation, investigate astrochemistry, and detect the light that is finally reaching us from the universe’s earliest galaxies. ALMA’s first projects will flex the telescope’s capabilities in all of these fields and many… more.’

ALMA is said to be radically different from visible-light and infrared telescopes. It is the largest international array of linked antennas, acting as a single giant telescope (known as an interferometer), and it detects longer wavelengths than those of visible light. As a result, its images look quite unlike more familiar pictures of the cosmos.

By linking multiple telescopes, a higher-resolution image can be produced, depending on both the separation and the number of antennas. Larger separations mean that sharper images can be created and if more antennas are working together more detailed images can be produced.

ALMA will continue its construction phase in the Chilean Andes, in the Atacama Desert, during its early science observations.

Each new, climate-armoured telescope will join the array and be linked via fibre-optic cabling. The views from each distant telescope are assembled into one large view by one of the world’s fastest, special-purpose supercomputers, the ALMA Correlator.

Designed and built by the NRAO Technology Center in Charlottesville, Virginia, the ALMA Correlator performs 17 quadrillion operations per second.

Astronomers from around the world have submitted more than 900 proposals for observations, a nine-fold level of oversubscription that is claimed to be a record for a telescope. Successful projects were chosen based on their scientific merit, regional diversity and their relevance to ALMA’s major science goals.