The feed cabin supporting system of China's single-aperture spherical telescope "FAST" is under test in Qiannan of southwest China's Guizhou Province, Nov. 21, 2015. When it is completed in 2016, the five hundred meter aperture spherical telescope (FAST) will be the world's largest, overtaking Puerto Rico's Arecibo Observatory, which is 300 meters in diameter. (Xinhua/Jin Liwang)

The feed cabin supporting system of China's single-aperture spherical telescope "FAST" is under test in Qiannan of southwest China's Guizhou Province, Nov. 21, 2015. When it is completed in 2016, the five hundred meter aperture spherical telescope (FAST) will be the world's largest, overtaking Puerto Rico's Arecibo Observatory, which is 300 meters in diameter. (Xinhua/Jin Liwang)

The feed cabin supporting system of China's single-aperture spherical telescope "FAST" is under test in Qiannan of southwest China's Guizhou Province, Nov. 21, 2015. When it is completed in 2016, the five hundred meter aperture spherical telescope (FAST) will be the world's largest, overtaking Puerto Rico's Arecibo Observatory, which is 300 meters in diameter. (Xinhua/Jin Liwang)

The feed cabin supporting system of China's single-aperture spherical telescope "FAST" is under test in Qiannan of southwest China's Guizhou Province, Nov. 21, 2015. When it is completed in 2016, the five hundred meter aperture spherical telescope (FAST) will be the world's largest, overtaking Puerto Rico's Arecibo Observatory, which is 300 meters in diameter. (Xinhua/Jin Liwang)

The feed cabin supporting system of China's single-aperture spherical telescope "FAST" is under test in Qiannan of southwest China's Guizhou Province, Nov. 21, 2015. When it is completed in 2016, the five hundred meter aperture spherical telescope (FAST) will be the world's largest, overtaking Puerto Rico's Arecibo Observatory, which is 300 meters in diameter. (Xinhua/Jin Liwang)

The feed cabin supporting system of China's single-aperture spherical telescope "FAST" is under test in Qiannan of southwest China's Guizhou Province, Nov. 21, 2015. When it is completed in 2016, the five hundred meter aperture spherical telescope (FAST) will be the world's largest, overtaking Puerto Rico's Arecibo Observatory, which is 300 meters in diameter. (Xinhua/Jin Liwang)

The feed cabin supporting system of China's single-aperture spherical telescope "FAST" is under test in Qiannan of southwest China's Guizhou Province, Nov. 21, 2015. When it is completed in 2016, the five hundred meter aperture spherical telescope (FAST) will be the world's largest, overtaking Puerto Rico's Arecibo Observatory, which is 300 meters in diameter. (Xinhua/Jin Liwang)

The feed cabin supporting system of China's single-aperture spherical telescope "FAST" is under test in Qiannan of southwest China's Guizhou Province, Nov. 21, 2015. When it is completed in 2016, the five hundred meter aperture spherical telescope (FAST) will be the world's largest, overtaking Puerto Rico's Arecibo Observatory, which is 300 meters in diameter. (Xinhua/Jin Liwang)

The feed cabin supporting system of China's single-aperture spherical telescope "FAST" is under test in Qiannan of southwest China's Guizhou Province, Nov. 21, 2015. When it is completed in 2016, the five hundred meter aperture spherical telescope (FAST) will be the world's largest, overtaking Puerto Rico's Arecibo Observatory, which is 300 meters in diameter. (Xinhua/Jin Liwang)

A piece of reflector of China's single-aperture spherical telescope "FAST" is seen as the project is under construction in Qiannan of southwest China's Guizhou Province, Nov. 21, 2015. When it is completed in 2016, the five hundred meter aperture spherical telescope (FAST) will be the world's largest, overtaking Puerto Rico's Arecibo Observatory, which is 300 meters in diameter. (Xinhua/Jin Liwang)

A piece of reflector of China's single-aperture spherical telescope "FAST" is seen as the project is under construction in Qiannan of southwest China's Guizhou Province, Nov. 21, 2015. When it is completed in 2016, the five hundred meter aperture spherical telescope (FAST) will be the world's largest, overtaking Puerto Rico's Arecibo Observatory, which is 300 meters in diameter. (Xinhua/Jin Liwang)

A worker mounts a piece of reflector on China's single-aperture spherical telescope "FAST" in Qiannan of southwest China's Guizhou Province, Nov. 21, 2015. When it is completed in 2016, the five hundred meter aperture spherical telescope (FAST) will be the world's largest, overtaking Puerto Rico's Arecibo Observatory, which is 300 meters in diameter. (Xinhua/Jin Liwang)

China's single-aperture spherical telescope "FAST" is seen under construction in Qiannan of southwest China's Guizhou Province, Nov. 21, 2015. When it is completed in 2016, the five hundred meter aperture spherical telescope (FAST) will be the world's largest, overtaking Puerto Rico's Arecibo Observatory, which is 300 meters in diameter. (Xinhua/Jin Liwang)

China's single-aperture spherical telescope "FAST" is seen under construction in Qiannan of southwest China's Guizhou Province, Nov. 21, 2015. When it is completed in 2016, the five hundred meter aperture spherical telescope (FAST) will be the world's largest, overtaking Puerto Rico's Arecibo Observatory, which is 300 meters in diameter. (Xinhua/Jin Liwang)