BEIJING, April 27 (Xinhua) -- China is constructing the largest steerable radio telescope in Asia with a 70-meter-diameter antenna to receive data from its first Mars exploration mission which is expected to be launched this year.

China aims to complete orbiting, landing and roving on the red planet in one mission, which has been named Tianwen-1.

The telescope, with an antenna the size of nine basketball courts, was built by the National Astronomical Observatories of the Chinese Academy of Sciences in Wuqing District of northern China's Tianjin.

It will be a key facility to receive scientific data sent back by the Mars probe, which can be up to 400 million km from Earth, and the signals will be very weak, said Li Chunlai, deputy chief designer of China's first Mars exploration mission.

China has successfully launched four lunar probes and completed orbiting and landing on the moon.

However, the distance between the moon and Earth is about 360,000 km to 400,000 km, while the distance between Mars and Earth is 56 million km to 400 million km. The longest Earth-Mars distance is 1,000 times that between Earth and the moon.

"Therefore, receiving extremely weak signals from Mars will be a great challenge," Li said, adding that only a telescope with a large antenna, working in combination with three existing telescopes in Beijing and the southern Chinese city of Kunming, can realize the data receiving. Enditem