China is preparing to make the first attempt to stop-over robotic aircraft on the great side of the Moon.
Tin Lander and Rover are expected to be deployed to face the next day, state media report.
Vehicles carrying a set of & # 39; instruments designed to characterize the geology of the region, as well as biological experiment.
In recent days, the spacecraft Chang & # 39; e 4 reduced its orbit in preparation for landing.
During the weekend, Chinese state media said the probe had entered into an elliptical path around the Moon, bringing vehicles to 15km (9 miles) of the lunar surface at its closest point.
The authorities did not specify the exact time of the attempt to touch the crane Von Kármán. But a report in the China Daily newspaper suggests that state-run Chang & # 39; e 4 can & # 39; drops on its drivers in & # 39; some time from 2-3 & # 39; January.
The goal of most will change this mission in & # 39; riskier risk and complex than its predecessor, Chang & # 39; e-3 – that handled in the Imbrium Mare region of the Moon in 2013. But the latest shooting & # 39; Moon China will pave the way for the country to deliver rock and lunar dust samples to Earth.
Andrew Coates, professor of physics at the Laboratory of Space Science & # 39; of & # 39 Mullard; UCL f & # 39; Surrey, told BBC News: "This daring mission will drop almost 50 years since the landing of & # 39; historic Apollo and will be followed later in 2019 by mission & # 39 ; return & # 39; Chinese sample. "
Because of a phenomenon called "tidal locking", we see only "face" one of the Moon from Earth. This is because the Moon takes so much time to turn on its own axis as it takes to complete one orbit of the Earth.
Side remote lunar of & # 39; often called "the dark side", but "dark" in & # 39; in this case means "unseen" rather than "non & # 39; light ". In fact, both the sides as well as the close distance of the Moon experience daytime and night.
But the most senior side has a thicker crust is equipped with & # 39; more craters. There are also very few "tide" – "dark waters bażaltiċi" created by lava flows – which are evident on the part of & # 39; close.
The crane is located at Von Kármán & # 39; much larger feature – the South Pole-Aitken Basin (SPA) – thought to be formed by a giant impact early in the history of the Moon.
"This massive structure is & # 39; more than 2,500km in diameter and 13km deep, one of the largest craters of & # 39; impact in the Solar System and the largest, deepest and oldest basin on the Moon, "said Prof Coates.
And where there is scientific interest. The event responsible for cutting the dock of SPAs he thought it was so strong, punched from the layer & # 39; out of the Moon, known as the shell, and & # 39; down in an area called the mantle. The researchers want to train instruments on any mantle rock exposed by the disaster.
The science team also hopes to study parts of the sheet & # 39; molten rock that would fill the Southern Basin Pole-Aitken newly formed, and b & # 39; thus enabling them to identify variations in its composition.
The third objective is to study the distant side of the regolith, the crushed rock and dust that make up the surface.
"The information on the composition in situ b & # 39; in particular will be & # 39; great value to understand the formation of the Moon," commented Andrew Coates.
Challenge & # 39; landing
S & # 39; now, China has followed the steps of the missions of the US and Soviet, carefully build its capabilities. But this mission marks the first for any space agency.
The robust character of the far side, with its undulating topography, poses particular challenges to the vehicle landed b & # 39; safely.
When touching down on a jagged outcrop explains immediate failure of the mission.
The crane option Von Kármán as the site & # 39; landing should give a lot to the fact that it is flatter than any place in the southern basin Pole-Aitken, according to Chinese scientists .
The descent to the lunar surface divided into & # 39; six phases. The first three – initial deceleration, adjustment & # 39; & # quick and adjusting 39; reorientation, and approach – will be controlled from Earth.
For the last three – hanging, avoiding hazards, and slow descent – the landing takes control, assume autonomous control.
Seeds and eggs
The Lander and Rover originally built as back-ups for the mission Chang & # 39; e 3 2013. However, they received important modifications to the ambitious touchdown on the big side.
Static landing & # 39; & # 39 Chang e 4 carrying two cameras; experiment & # 39; radiation built with German called LND; and spectrometers to perform radio astronomy observations & # 39; low frequency.
Scientists believe that a large part can & # 39; is an excellent place to conduct radio astronomy, because it is shielded from radio noise Earth. The work of the spectrometer is designed to test this idea.
The descent will also carry container & # 39; 3kg (6.6lb) with plant seed potatoes and arabidopsis – as well as silkworm eggs – to make biological studies. The experiment "mini lunar biosphere" was designed by 28 Chinese universities.
The rover will carry a panoramic camera; Radar inform under the lunar surface; imaging spectrometer for identifying minerals; and an experiment to examine the interaction of solar wind (a stream of & # 39; energized particles from the Sun) with the lunar surface.
F & # 39; article for the Planetary Society based on the United States in & # 39; in September, Dr. Long Xiao, University of China Ġeosjenzi (Wuhan) said: "Chang & # 39; e 4 will be the first exploration of humanity & # 39; on the side of the lunar. the challenge faced by remote mission is communication. no view of the World, there is no way to established direct radio link. "
Therefore, the landing must communicate with & # 39; World & # 39 through; satellite & # 39; relay named Queqiao, launched in China & # 39; May & # 39; this year.
Queqiao revolve around 65,000 km (40,000 meters) beyond the Moon, around Lagrange point – type & # 39; gravitational parking space which remains & # 39; visible to terrestrial stations in China and other countries such as Argentina.
The Lander and Rover launched from the Xichang Satellite Launch Center in China on 7 & # 39; December; vehicles arrived in lunar orbit on 12 & # 39; December.
The Chinese mission is part of a larger program of moon exploration. The first and second missions Chang & # 39; e were designed to collect data from orbit, while the third and fourth built for surface operations.
Chang & # 39; e 5 and 6 are missions & # 39; & # 39 return; samples, leading the rocks and lunar soil to laboratories on Earth.
Follow Paul on Twitter.