Space

China stakes far side of Moon

By Ted Bonnitt on January 8th, 2019
China stakes far side of Moon
Soon after landing on the unexplored back side of the Moon, China's rover "Yutu" drove off the lander. Credit: CNSA
Soon after landing on the unexplored back side of the Moon, China's rover "Yutu" drove off the lander. Credit: CNSA

China achieved a big first in space by successfully soft landing a rover on the far side of the moon, a major the technical feat.

The lander, Chang’e 4 arrived on January 3 and deployed the Yutu rover. It will search for evidence of the moon’s composition on the side that Earth never sees due to the two planets’ orbital dance influenced by tidal flows that slowed the moon’s rotation.

Chang’e 4 landed at the Von Kármán crater, on a smooth volcanic floor located within the great Aitken basin. China’s space agency, CNSA explained the chosen destination, “The material composition and geological age of the Von Kármán crater is representative and valuable for studying the early history of the moon and the solar system. The back of the moon is also a rare quiet place that shields the radio signal interference from the Earth.”

The back side of the moon offers clearer radio astronomy opportunities without the manmade electronic noise from Earth, as the moon’s mass blocks all radio signals from Earth. 

The “quiet side” is what made the successful landing so significant. Because direct communication between Earth and the lander is impossible, China earlier launched the “Queqiao” satellite in an orbit that circles behind the moon to relay signals between the spacecraft and Earth. Chang’e 4 mission planners programmed the lander to autonomously find a safe place to land during its descent to the moon’s surface. 

The lander used rockets to descend to about 300 feet above the moon’s surface and hover briefly as onboard high tech cameras and laser measurement systems scanned for a safe, open place to land in the rough terrain. Chang’e 4 found a spot and rocketed down to the surface almost vertically to avoid the surrounding hills.

The lander and rover will probe the unexplored area, including geology, solar winds and the moon’s interior. The probes will also try to understand why the back side of the moon with its preserved ancient composition and deep creators is different from the Earth siding face, hopefully offering new data on the moon’s origin. 

China has follow-up unmanned missions planned to the back side of the moon later this year, which will attempt to collect and return moon samples to Earth.


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