The main part of the world’s most powerful and largest radio observatory was inaugurated in mid-March in the world’s coldest desert at an altitude of 5,000 meters in northern Chile. Located in the super-arid Atacama Desert, the Atacama Large Millimeter/submillimeter Array — known as ALMA — consists of 66 state-of-the-art radio telescopes spread over an area of 16 sq. km.
Japan, the United States and leading European countries have spent some ¥100 billion on the project, with Japan shouldering ¥30 billion of the cost. In the course of carrying out the project, a tragedy happened: Professor Koichiro Morita, who took part in designing 16 ALMA telescopes, was murdered during a robbery in his apartment in Santiago last May. It is hoped that ALMA will make great contributions to enhancing human knowledge of the birth and evolution of the universe.
The 66 radio telescope forming ALMA are 54 parabola antennas, each having a diameter of 12 meters, and 12 parabola antennas, each seven meters across. By spreading these telescopes to a distance of up to 20 km, it is possible to get the observation data as if they were from a radio telescope with a diameter of up to 20 km.
By utilizing radio wave interference, computers synthesize data from each telescope as if they acted as one giant radio telescope. To prevent astronomers from being affected by altitude sickness, the telescopes will be remotely controlled from a facility at an altitude of 2,900 meters.
These radio telescopes will be able to catch weak radio millimeter waves (1 to 10 mm wavelength) and submillimeter waves (0.1 to 1 mm wavelength). They will be able to peer into the dust and gases that fill the universe but which optical telescopes cannot capture.
Japan built a 45-meters-in-diameter radio telescope at the National Observatory’s Nobeyama Solar Radio Observatory in Nagano Prefecture because the amount of vapor that absorbs millimeter waves is small there.
Still it is not the perfect site. Japanese researchers searched for the best site and chose the Atacama Desert, which is 5,000 meters from the sea level and extremely dry and has flat land extending for a distance of more than 10 km.
Hopefully ALMA will help accumulate data on how galaxies are formed, how organic molecules, which are ingredients of life, are distributed in the universe and how planets, where life can be born and develop, are formed.
The resolution of ALMA is about 10 times better than that of the Subaru telescope placed at a 4,139-meter-high point on Mount Mauna Kea, Hawaii Island, and the resolution of the Hubble Space Telescope. By combining data obtained by ALMA and those from optical telescopes, it will become possible to study the evolution of the universe just after its birth.
The researchers involved show strong enthusiasm. It is hoped that ALMA will go into full operation without a hitch.