China is set to land a robotic rover on the surface of the Moon, a major step in the Asian superpower's ambitious programme of space exploration.
On Saturday afternoon (GMT), a landing module will undergo a powered descent, using thrusters to perform the first soft landing on the Moon in 37 years.
Several hours later, the lander will deploy a robotic rover called Yutu, which translates as "Jade Rabbit".
The touchdown will take place on a flat plain called the Bay of Rainbows.
The Chang'e-3 mission launched on a Chinese-developed Long March 3B rocket on 1 December from Xichang in the country's south.Continue reading the main story
China is saying: 'We are doing something that only two other countries have done before - the US and the Soviet Union”End QuoteDean ChengHeritage Foundation
"On the evening of December 14, Chang'e-3 will carry out a soft landing on the lunar surface," said a post on the mission's official blog on Sina Weibo, the Chinese version of Twitter.
The task was described as the mission's "most difficult" in the post, written by the Chinese Academy of Sciences on behalf of the space authorities.
It is the third robotic rover mission to land on the lunar surface, but the Chinese vehicle carries a more sophisticated payload, including ground-penetrating radar which will gather measurements of the lunar soil and crust.
The 120kg (260lb) Jade Rabbit rover can reportedly climb slopes of up to 30 degrees and travel at 200m (660ft) per hour.
Its name - chosen in an online poll of 3.4 million voters - derives from an ancient Chinese myth about a rabbit living on the moon as the pet of the lunar goddess Chang'e.
According to translated documents, the landing module will begin actively reducing its speed at about 15km from the Moon's surface.
When it reaches a distance of 100m from the surface, the craft will fire thrusters to slow its descent.
At a distance of 4m, the lander switches off the thrusters and free-falls to the lunar surface.
The Jade Rabbit is expected to be deployed on Saturday evening, driving down a ramp lowered by the Chang'e-3 landing module.
Reports suggest the lander and rover will photograph each other at some point on Sunday.
The Chang'e-3 mission launches from Xichang, south China
According to Chinese space scientists, the mission is designed to test new technologies, gather scientific data and build intellectual expertise.
Dean Cheng, a senior research fellow at the Heritage Foundation, a conservative think-tank in Washington DC, said China's space programme was a good fit with China's concept of "comprehensive national power". This might be described as a measure of a state's all-round capabilities.
Space exploration was, he told BBC News, "a reflection of your economic power, because you need spare resources to have a space programme. It clearly has military implications because so much space technology is dual use".
He added: "It reflects your scientific and technological capabilities, it supports your diplomacy by making you appear strong.
"China is saying: 'We are doing something that only two other countries have done before - the US and the Soviet Union."
Mr Cheng explained that the mission would provide an opportunity to test China's deep-space tracking and communications capability.
"The rover will reportedly be under Earth control at various points of its manoeuvres on the lunar surface," Mr Cheng wrote in a blog post.
"Such a space observation and tracking system has implications not only for space exploration but for national security, as it can be used to maintain space surveillance, keeping watch over Chinese and other nations' space assets."
The European Space Agency said it would provide communications support on the mission. Erik Sorenson, head of ground facilities at the European Space Operations Centre in Darmstadt, Germany, said Esa's tracking facilities would be able to reconstruct the craft's trajectory during descent and determine its precise location on the Moon.
China has been methodically and patiently building up the key elements needed for an advanced space programme - from launchers to manned missions in Earth orbit to unmanned planetary craft - and it is investing heavily.
The lander's target is Sinus Iridum (Latin for Bay of Rainbows) a flat volcanic plain thought to be relatively clear of large rocks. It is part of a larger feature known as Mare Imbrium that forms the right eye of the "Man in the Moon".
After this, a mission to bring samples of lunar soil back to Earth is planned for 2017. And this may set the stage for further robotic missions, and - perhaps - a crewed lunar mission in the 2020s.
"[Chang'e-3] is probably laying some of the groundwork for a manned mission," said Mr Cheng.