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A Long March 3B rocket
launches China’s Chang'e 4 lunar probe from the Xichang Satellite Launch
Center on Dec. 7, 2018 (Dec. 8 local Chinese time). The probe is
expected to make the first-ever soft landing on the far side of the moon
in early January 2019.
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Probe on far side of moon
BEIJING: China launched a rover destined to land on the far side of the moon, a global first that would boost Beijing’s ambitions to become a space superpower, state media said.
The Chang’e-4 lunar probe mission – named after the moon goddess in Chinese mythology – launched early yesterday on a Long March 3B rocket from the south-western Xichang launch centre at 2.23am (local time), according to the official Xinhua news agency.
The blast-off marked the start of a long journey to the far side of the moon for the Chang’e-4 mission, expected to land around the New Year to carry out experiments and survey the untrodden terrain.
“Chang’e-4 is humanity’s first probe to land on and explore the far side of the moon,” said the mission’s chief commander He Rongwei of China Aerospace Science and Technology Corp, the main state-owned space contractor.
“This mission is also the most meaningful deep space exploration research project in the world in 2018,” He said.
Unlike the near side of the moon that is “tidally locked” and always faces the earth, and offers many flat areas to touch down on, the far side is mountainous and rugged.
It was not until 1959 that the Soviet Union captured the first images of the heavily cratered surface, uncloaking some of the mystery of the moon’s “dark side”.
No lander or rover has ever touched the surface there, positioning China as the first nation to explore the area.
China over the past 10 or 20 years has been systematically ticking off the various firsts that America and the Soviet Union did in the 1960s and 1970s in space exploration,” said Jonathan McDowell, an astronomer at the Harvard-Smithsonian Center for Astrophysics.
“This is one of the first times they’ve done something that no one else has done before.”
It is no easy technological feat – China has been preparing for this moment for years.
A major challenge for such a mission is communicating with the robotic lander: as the far side of the moon always points away from earth, there is no direct “line of sight” for signals.
As a solution, China in May blasted the Queqiao (“Magpie Bridge”) satellite into the moon’s orbit, positioning it so it can relay data and commands between the lander and earth.
Adding to the difficulties, Chang’e-4 is being sent to the Aitken Basin in the lunar south pole region – known for its craggy and complex terrain – state media has said.
The probe is carrying six experiments from China and four from abroad.
They include low-frequency radio astronomical studies – aiming to take advantage of the lack of interference on the far side – as well as mineral and radiation tests, Xinhua cited the China National Space Administration as saying.
The experiments also involve planting potato and other seeds, according to Chinese media reports.
Beijing is pouring billions into its military-run space programme, with hopes of having a crewed space station by 2022, and of eventually sending humans to the moon. — AFP
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Exploring new terrain: A Long March 3B rocket
taking off with the rover that is destined to land on the far side of
the moon. — AFP
|
China's robotic Chang'e 4 spacecraft streaked away from Earth today (Dec. 7), launching atop a Long March 3B rocket from the Xichang Satellite Launch Center at about 1:23 p.m. EST (1823 GMT; 2:23 a.m. on Dec. 8 local China time).
If all goes according to plan, Chang'e 4 will make history's first landing on the lunar far side sometime in early January. The mission, which consists of a stationary lander and a rover, will perform a variety of science work and plant a flag for humanity in a region that remains largely unexplored to date. [China's Moon Missions Explained (Infographic)]
China’s Chang'e 4 lunar probe lifts off the pad at Xichang Satellite Launch Center on Dec. 7, 2018 (Dec. 8 local Chinese time).
Going where no probe has gone before
The moon is tidally locked to Earth, meaning the natural satellite takes about the same amount of time to spin once on its axis as it does to orbit our planet. So, here on Earth, we always see the same face of our cosmic neighbor.That would be the near side. The far side remains forever out of view, and that explains why this obscured surface has yet to welcome a robotic visitor. Communicating with a far-side lander or rover is difficult, because the entirety of the moon's solid, rocky body would block direct signals traveling to and fro.
The far side of the moon and distant Earth, imaged by China's Chang'e 5 T1 mission service module in 2014. The Chang'e 4 mission will launch toward the far side on Dec. 7, 2018. Credit: Chinese Academy of Sciences
To solve this problem, China launched a satellite called Queqiao this past May. Queqiao has set up shop at the Earth-moon Lagrange point 2, a gravitationally stable spot beyond the moon from which the satellite will be able to relay communications between mission control and Chang'e 4.
The spacecraft's signals will likely be coming from the floor of Von Kármán Crater, a 115-mile-wide (186 kilometers) hole in the ground that's the mission's expected landing site. Von Kármán is part of the South Pole-Aitken Basin, one of the biggest impact features in the solar system; it spans a whopping 1,600 miles (2,500 km) from rim to rim.
China's Yutu moon rover, photographed by the Chang'e 3 lander in December of 2013. The lunar far-side mission, Chang'e 4, which launched on Dec. 7, 2018, was designed as a backup for Chang'e 3.
Lots of data
Chang'e 4 features a total of eight scientific instruments. The landers' are called the Landing Camera (LCAM), the Terrain Camera (TCAM), the Low Frequency Spectrometer (LFS), and the Lunar Lander Neutrons and Dosimetry (LND), which was provided by Germany.
The rover sports the Panoramic Camera (PCAM), the Lunar Penetrating Radar (LPR), the Visible and Near-Infrared Imaging Spectrometer (VNIS), and the Advanced Small Analyzer for Neutrals (ASAN), a contribution from Sweden.
This gear will allow Chang'e 4 to characterize its surroundings in great detail. For example, the LFS will return data about surface composition, while the LPR will tease out the layered structure of the moon's subsurface.
Such information could help scientists better understand why the lunar far side is so different from the near side. For example, huge, dark basaltic plains called maria cover much of the near side but almost none of the far side. (By the way, don't call the far side the "dark side"; it receives just as much sunlight as the near side.)
Chang'e 4 will also conduct some radio-astronomy work, taking advantage of the peace and quiet on the far side, which is shielded from the radio chatter coming from Earth. Queqiao is collecting astronomy data as well, using an onboard instrument called the Netherlands-China Low-Frequency Explorer.
The spacecraft carries a biological experiment as well: a small tin containing silkworm eggs and seeds of tomato and Arabidopsis plants. Researchers will keep tabs on how these organisms live and develop on the lunar surface. [Moon Master: An Easy Quiz for Lunatics]
March to the moon
Chang'e 4 marks the latest step in China's ambitious, long-term moon-exploration strategy.The nation launched the Chang'e 1 and Chang'e 2 spacecraft to lunar orbit in 2007 and 2010, respectively. In December 2013, Chang'e 3 put a lander and a rover named Yutu down on the moon's near side. (Chang'e 4 was originally developed as a backup to Chang'e 3 but was repurposed after the latter's success.)
And in October 2014, China launched Chang'e 5T1, which sent a test capsule on an eight-day trip around the moon that ended in a parachute-aided touchdown here on Earth.
All of this is leading up to the Chang'e 5 sample-return mission, which could launch toward the near side as early as next year. (The nation's line of robotic lunar missions is named after Chang'e, a moon goddess in Chinese mythology.)
And then there's the crewed side of things. Chinese officials have said they want to land people on the lunar surface, though the timeline for this goal is unclear. The moon is not China's human-spaceflight focus in the near term; the country is working to get a crewed space station up and running in Earth orbit by the early 2020s.
Source: Space.com. by
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