1. The Ruler and Eye

The Shanghai Institute of Technical Physics of the Chinese Academy of Sciences’ laser range sensor works as the “ruler” of the lunar lander and rover.

When the lander is 15 kilometers above the moon, the newly developed “ruler” begins its work with two laser beams, one for short distances and the other for long.

“The moon’s far side has more craters than its near side and the terrain there is more rugged, so, the landing is more difficult,” said Cheng Pengfei, deputy researcher of the institute.

Cheng said the lander will rotate 90 degrees during landing, which requires the sensor to shift from using the long-distance laser beam to the short-distance one. For the Chang’e-3 probe, which landed on the moon’s near side, that happened when it was 3 kilometers above the surface. But the Chang’e-4 will operate at about 6 to 8 kilometers, which is more challenging.

The new sensor, with a detection range exceeding 40 kilometers and with superior range measurement accuracy, is designed for the extreme space environment.

After Chang’e-4 lands, the mirror-like Visible and Near-infrared Imaging Spectrometer, working as an “eye,” will start work. It will collect spectral information on the moon’s surface for analysis of its mineral composition.

“Compared with the VNIS used for the Chang’e-3 lunar probe, the new device has an optimized detection performance, and the data collection time is reduced to half,” said Xu Rui from the institute.

Xu said the technology was not just for the lunar probe. “It has a range of applications, such as exploration for minerals and the treatment of air and water pollution,” Xu said.