Construction of the world's largest radio telescope - the 500-meter Aperture Spherical Radio Telescope - is a project that comes with a 700 million yuan price tag.

As the name suggests, it has a diameter of 500 meters and stands 138 meters high, around the same height as a 50-story building. The larger size means greater sensitivity, enabling it to pick up smaller and weaker signals. In theory, FAST can receive electromagnetic signals from 13.7 billion light years away, nearly to the edge of the known universe.

It also has a flexible focus to follow observed objects. FAST has a fixed spherical shape, but an  "active surface" as its reflection panel will form a simultaneous paraboloid to receive signals.

One of the the telescope's design goals is to collect signals into a small tablet-size space to observe the weakest signal. Its cable net structure is connected by more than 7,000 steel wires. Deviation of each can be controlled to within one millimeter. 

Based on its capacity, FAST is expected to reach out to other galaxies and search for deep-space pulsars. Between 50 and 80 pulsars are expected to be found in the first operational year. Understanding the fundamental physics of pulsars will help us understand the "Big Bang". Scientists hope to search for possible signals and evidence of alien lifeforms.

Soon, FAST will be ready to investigate some of the biggest mysteries in our universe.