They hope to test their hypothesis that volcanoes on that side became inactive 4 billion years ago. Great question frankly, this article goes into it in much mo

They hope to test their hypothesis that volcanoes on that side became inactive 4 billion years ago. Great question frankly, this article goes into it in much more detail (I just selected a likely looking blurb, there are other elements of the theory) https://www.cnsa.gov.cn/english/n6465652/n6465653/c10523137/content.html https://www.cnsa.gov.cn/english/n6465652/n6465653/c10523137/...