Chang’e 4 launches China’s bid to be first on dark side of the moon
- Lunar lander and rover spacecraft blasts off on Saturday in challenging mission to explore moon’s lesser-known far side
- Success would significantly boost the standing of the Chinese space programme
A rocket carrying China’s latest lunar lander and rover spacecraft, Chang’e 4, blasted off at about 2.23am local time on Saturday from Xichang Satellite Launch Centre in southern China, in humankind’s first attempt to land on the far side of the moon.
China's state Xinhua news agency confirmed on Twitter that China had launched the lunar probe in the early hours of Saturday. It's expected to make first-ever soft landing on the far side of the moon, it said.
The far side, also known as the dark side because it faces away from Earth, remains comparatively unknown, with a different composition from sites on the near side, where previous missions have landed.
If successful, the mission would propel the Chinese space programme to a leading position in one of the most important areas of lunar exploration.
Its plan to soft-land Chang’e 4 on the far side of the moon is challenging because any direct communications between the Earth and the rover once it is there will be blocked by the other hemisphere, scientists have said.
To solve the problem, China in May launched a relay satellite, Queqiao, between the Earth and the moon. Operating about 400,000km (250,000 miles) from the Earth, Queqiao will pass on signals to the lunar lander and rover of Chang’e 4.
Zhang Lei, an engineer at the Xi'an Satellite Control Centre, was quoted by China's state television station CCTV as saying that it is a "first-ever effort in the world" to bridge the communication between the Earth and the dark side of the moon through a relay satellite”. The task is "hugely challenging" and "without any experience for reference", he said.
Ye Quanzhi, an astronomer at the California Institute of Technology in the US, said that simply “saying Chang’e 4 is doing something that has not been tried before would be an understatement”.
“The landing area, the South Pole-Aitken basin, is the oldest basin on the moon, meaning that we could get first-hand information about the distant past of the moon.”
Aitken basin, discovered by the manned American spacecraft Apollo 8 in 1968, has a diameter of about 2,500km, while that of the moon itself is 3,400km.
“It is also one of the largest known impact structures in the solar system, suggesting it was formed from a gigantic impact and could have excavated a lot of materials from the interior,” Ye said. “If Chang’e 4 is able to sample these materials, we will get to learn the composition of the moon’s interior.”
The launch of Chang’e 4’s lander and rover suggests the completion of the second phase of the Chinese Lunar Exploration Programme (CLEP), one of 16 key technologies identified by the Chinese government.
China plans to launch a returnable spacecraft called Chang’e 5 by 2020, under the third and final phase of the plan. Chang’e 5 will include a lunar lander and a rover that could return to the Earth after collecting samples and performing surveys on the planet’s satellite, according to the CLEP.
Chang’e 4 will pick up the work begun by Yutu, the lunar rover of Chang’e 3, which landed on the moon in December 2013. Yutu, or Jade Rabbit, stopped moving due to a mechanical problem about 40 days after the lunar rover landed there.
“The design of the Chang’e 4 lunar rover has been improved based on the previous one, meaning it could work for at least a few years on the moon,” Wu Weiren, chief designer of the CLEP, said in August.
“We have minimised the amount of electrical wiring that will be exposed in the extreme temperatures on the moon so they won’t wear off easily.”
The rover of Chang’e 4 will land on the moon in about two weeks’ time.
The mission is part of China’s plan to expand its influence in space. Last month, it sent two Beidou satellites into space, completing its GPS-style satellite network. China said it would provide services to countries taking part in the “Belt and Road Initiative”, its transcontinental infrastructure building and financing strategy, by the end of this year.