ALMA: Exploring the Outer Limits of Radio Astronomy
Alwyn Wootten
ALMA -- the Atacama Large Millimeter/Submillimeter Array -- will be a
single instrument composed of more than 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.
ALMA's 12m antennas--about five dozen of them, will be deployed 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. It will provide
scientific insight at wavelengths complementary to those of the Very Large
Array, Gemini, the HST and the JWST and with the same image detail and clarity.
ALMA is the complete imaging, spectroscopic instrument for the
millimeter/submillimeter.