In a valley deep in southwest China’s mountainous Guizhou Province, thousands of white steel pillars and cables enclose a large natural hollow.
Formed 45 million years ago with collapse of a karst cave, the hollow is now home to the world's largest radio telescope, with a dish area as large as 30 football fields. It takes about half an hour to make one circuit of its 1600-meter-circumference.
Local residents were moved away to towns and enjoy better living standards. Villagers in other depression communities admired their luck, saying they should thank the aliens.
Scientists say that it will become a big sensitive “ear”, listening to subtle sounds from distant universes, decoding cosmic messages.
With an investment of 1.2 billion yuan, China’s largest ever astronautics project was begun in March 2011 and will be completed in September next year.
“Once completed, the radio telescope will maintain a lead position in the world for 20 to 30 years,” says Li Di, a scientist of National Astronomical Observatories, Chinese Academy of Science. “We welcome scientists from around the world to come.”
Technicians are assembling the telescope's reflector, which is 500 meters in diameter and made up of 4,450 panels. Each panel is an equilateral triangle with a side length of 11 meters. Cables are fixed to the back of each panel so that it can change positions with an accuracy of 1 mm, ensuring the telescope can receive from different angles.
Once completed, the Five-hundred-meter Aperture Spherical radio Telescope, or “FAST”, will overtake Puerto Rico's Arecibo Observatory, which is 305 meters in diameter. It will be 10 times more sensitive than the steerable 100-meter telescope near Bonn, Germany, says Zhang Haiyan, deputy director of the general office of the FAST Project.
FAST will enable astronomers to jumpstart many science goals. For example, they could survey natural hydrogen in distant galaxies, detect faint pulsars, look for the first star shining, or even hear possible signals from other civilizations.
The key science goals of FAST are based on observables between 70MHz and 3 GHz, including the 21 cm HI hyperfine structure line, pulsar emissions and radio continuum.
Perhaps the most exciting goal of FAST is the search for other life. Instead of searching for life per se, scientists are looking for the molecules that constitute life.
Scientists have found about 180 kinds of molecules in space, including carbonic oxide, ammonia, and methanol.
“Just like eating and sleeping, curiosity about space is a basic instinct of human beings,” says Li. “Chinese scientists have made numerous contributions in mathematics, computer sciences, and particle physics in the past years under impoverished conditions, and now with the most advanced facility supported by the government, we are duty-bound to make a giant step forward.”
FAST under the sky