ALMA — the Atacama Large Millimeter Array — will be a single instrument composed of 64 high-precision antennas located on the Chajnantor plain of the Chilean Andes in the District of San Pedro de Atacama, 5,000 meters (16,500 feet) above sea level. ALMA’s primary function will be to observe and image with unprecedented clarity the enigmatic cold regions of the Universe, which are optically dark, yet shine brightly in the millimeter portion of the electromagnetic spectrum.

To bolster ALMA's sensitivity on scales between the antenna diameter of 12 m and the shortest baseline of 15 m the ACA, comprised of four 12 m telescopes along with twelve 7m antennas, built and equipped to the same specifications as those in the main array, will be contributed by Japan as part of its entry into the project. Japan is providing a separate signal correlator for the ACA similar in power to that of the large array. In addition, Japan is providing two additional receiver bands for all 80 antennas in Enhanced ALMA.

ALMA consists of an array of sixty-four 12m antennas with reconfigurable baselines ranging from 150 m to 18 km. The ability to reconfigure provides a zoom lens capability, allowing a resolution as fine as 0.01", a factor of five better than the Hubble Space Telescope Advanced Camera for Surveys. ALMA is designed to operate at wavelengths of 0.3 to 9 millimeters where the Earth’s atmosphere above a high, dry site is largely transparent and where clouds of cold gas as close as the nearest stars and as distant as the observable bounds of the universe all have their characteristic spectral signatures. It will provide scientific insight at wavelengths complementary to those of the Very Large Array and Gemini and with the same image detail and clarity. ALMA is the complete imaging, spectroscopic instrument for the millimeter/submillimeter.

ALMA is currently under development. More information about ALMA here (link).