Relay satellite for Chang'e-4 lunar probe enters orbit

World
Europe

The relay satellite for the planned Chang'e-4 lunar probe, which is expected to land on the far side of the Moon at the end of the year, has entered orbit, the China National Space Administration (CNSA) announced Thursday.

The satellite named Queqiao - Magpie Bridge in English - was launched on May 21 and entered the Halo orbit around the second Lagrangian (L2) point of the Earth-Moon system, about 65,000 kilometers from the Moon, at 11:06 a.m. BJT on Thursday.

"The satellite is the world's first communication satellite operating in that orbit, and will lay the foundation for the Chang'e-4, which is expected to become the world's first soft-landing, roving probe on the far side of the Moon," said Zhang Hongtai, president of the China Academy of Space Technology.

The concept of the Halo orbit around the Earth-Moon L2 point was first put forward by international space experts in the 1950s.

Diagram shows the satellite Queqiao's orbit. /CCTV Photo

"From Earth, the orbit looks like a halo for the Moon, which is where it got its name," said Zhang Lihua, project manager of the relay satellite.

He also said the Halo orbit was a three-dimensional irregular curve, which makes maintaining the satellite in orbit extremely difficult and complex.

The gravity of the Earth and Moon balances the orbital motion of the satellite, so it is relatively less fuel-hungry and can stay in the Halo orbit for a long time.

However, Zhang added that if there is any tiny disturbance, such as gravitational disturbance from other planets or the Sun, the satellite will leave orbit. "The orbit period is about 14 days. According to our current plan, we will conduct orbit maintenance every seven days."

Diagram shows the satellite Queqiao's orbit, a three-dimensional irregular curve. /CCTV Photo

"Queqiao is like a little kid running wild in orbit. If there's even the slightest negligence by our team, the satellite will be lost forever," said Guan Bin, a designer for the satellite's control system.

The team has also run a number of simulations to make sure the design is feasible and reliable.

In order to set up a communication link between Earth and the planned Chang'e-4 lunar probe, astrophysicists must keep the satellite stable and control its altitude, angle and speed with a high level of precision.

In their next step, the team will test the relay satellite's communication functions.

[Top image: Conceptual image shows China's lunar probe and relay satellite. /CCTV Photo]

Source(s): Xinhua News Agency