PolyU Provides Multi-disciplinary Support to the Nation's Historic Landing on the Far Side of the Moon - Seite 2

The team gathered information of more than 400,000 craters and over 20,000 boulders in the candidate landing regions. It had also analysed the terrain surface and calculated the gradient of the slopes to identify relatively flat sites for safe landing. Rock abundance of the region had to be considered in detail because boulders can be as large as 35 metres in diameter and can block the way of the rover, whereas small rocks may get into the wheels, hence creating problem in the rover's movement.

"The Chang'e-4 landing site is on the far side of the Moon, without direct radio communication from Earth," said Dr Wu. "In addition, the terrain surface of the landing region is also very rough with elevation differences up to 16km, which required a nearly perpendicular descent design. These made the mission very challenging."

The study in terrain occlusions to sun illumination and telecommunication is particularly important to ensure good illumination conditions to charge the solar panels on the lander and rover so that the onboard scientific sensors can be functional, and ensure good signal reception and data transmition between the control center on Earth and the lander and rover.

After the successful landing of Chang'e-4 on 3 January 2019, the team worked together with the CAST team to immediately locate the precise location of the lander and analysed the terrain occlusions to sun illumination and telecommunication around the lander for better scheduling of action of the lander and rover.

Dr Wu is excited to get involved in the project. "When I started my career in surveying, I have never dreamed of taking part in space exploration missions. But all things are possible if we are bold in taking out that one step," he shared.

Camera Pointing System 

Prof. Kai-leung YUNG, PolyU's Chair Professor (Precision Engineering) and Associate Head of Department of Industrial and Systems Engineering also leads a team to contribute to the nation's lunar probe by developing the Camera Pointing System (CPS) jointly with CAST.

The CPS weighs 2.8 kg and measures 85 cm (length) by 27 cm (width) and 16 cm (depth). Mounted on the upper part of the lander of Chang'e-4, CPS is capable of moving vertically by 120 degrees and rotating sideway by 350 degrees, under Moon's gravity (i.e. one sixth of Earth's gravity). It is deployed for capturing images of the Moon as well as facilitating movement of the lunar rover.