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Sunday, January 6, 2019

Chinese Chang'e mission ~ a small step for rover, giant leap for Nation !!

It is all about Moon & China  !  -  A robotic Chinese spacecraft named Chang’e 4 braked out of lunar orbit and slowed to a controlled touchdown on the far side of the moon Thursday, a first in the history of space exploration. The lander later deployed a small rover to explore the surrounding landscape.

The spacecraft landed at 0226 GMT on Jan. 3 (9:26 p.m. EST on Jan. 2) in the 110-mile-wide (180-kilometer) Von Karman crater, located in the southern hemisphere on the back side of the moon. Chinese websites released several images captured during the lander’s descent, and then revealed several more pictures taken of the mission’s six-wheeled rover as it drove down a ramp and onto the lunar surface. But Chinese state television did not provide a live broadcast of the landing, and reporters and space enthusiasts were kept in the dark, waiting for basic updates released on Chinese Weibo social media accounts. Chinese media also released few updates on the mission since its Dec. 7 launch aboard a Long March 3B rocket.

Finally, after Chinese officials confirmed a successful landing, the country’s television news networks trumpeted the achievement in a series of broadcasts and feature stories. The state-run Xinhua news agency said the Chang’e 4 mission arrived at the targeted landing site at 10:26 a.m. Beijing time Thursday.

The rover – named Yutu 2, or Jade Rabbit 2 – left the spacecraft, drove off a ramp and began making tracks on the moon’s surface at 10.22pm on Thursday, about 12 hours after Chang’e 4 landed. Lunar project chief designer Wu Weiren called the separation of the rover “a small step for the rover, but one giant leap for the Chinese nation.”

China’s Chang’e 4 mission could use soil tests and temperature measurements to reveal new clues to the cataclysmic collision that created the moon and uncover the origins of the water that is unexpectedly abundant in lunar soil. The Chang’e lunar mission is named after the Chinese moon goddess.  China’s state news agency, Xinhua, said the probe took a small plant called arabidopsis which is expected to produce the first flower on the moon. Other items included in a mini-biosphere include cotton, rapeseed, potato, fruit fly and yeast.

Amavasya and Purnima correspond to the two extreme states of the waxing – waning cycle of the moon. While Amavasai  is called no moon day or new moon day,  Pournami is called full moon day. Understand that in Sanskrit, "amā" means "together" and "vásya" means "to dwell" or "cohabit".  On Amavasya day, the earth’s satellite, moon is not visible.  In astronomy, the new moon is the first lunar phase, when the Moon and Sun have the same ecliptic longitude.  At this phase, the lunar disk is not visible to the unaided eye, except when silhouetted during a solar eclipse.

Yutu ("Jade Rabbit") is an robotic lunar rover that formed part of the Chinese Chang'e 3 mission to the Moon. It was launched in Dec  2013.  Now in news is Yutu 2.  For decades, the ‘dark side’ of the moon has been a reference to the vast unexplored spaces of the celestial body.  But now, on Thursday, a Chinese lunar rover landed on the ‘dark’ or ‘far’ side — a global first that boosts Beijing’s ambition to become a space superpower. The Chang’e-4 sent a photograph of the ‘dark side’ to the Queqio satellite, also operated by China.  A series of experiments has also been planned for the rover, including carrying out low-frequency radio astronomical tests, aiming to take advantage of the lack of interference on the moon’s far side.

China’s success in this regard is no mean feat: the dark side of the moon — unlike the near side — is extremely rugged, and this had earlier made landing difficult. This is not China’s first moon landing — it is the country’s second such probe, following the Yutu rover mission in 2013.   China’s rover Yutu 2 has begun exploring the far side of the moon after making a soft landing with the lander.  

Thursday’s successful touchdown in the unexplored South Pole-Aitken basin, the biggest known impact structure in the solar system, was hailed a major technical feat and is seen as an  important step towards China’s wider ambitions in space. Spacecraft have taken pictures of the moon’s far side before, but no lander has ever landed there. The moon’s far side is sometimes known as the dark side, although it is not darker than the near side in any literal sense. It undergoes the same phases of illumination by the Sun as the side facing Earth. But because the moon spins on its axis at exactly the same rate as it orbits Earth, one side remains permanently out of view.

It was only in 1959, when the first images of the far side were beamed back by the Soviet Union’s Luna 3, that intriguing differences were revealed. The far side is pockmarked by more craters and appears almost devoid of the seas of solidified lava, known as maria, that form the shadowy shape of a face that we see from Earth. The Jade Rabbit 2 rover has succeeded in establishing a digital transmission link with a relay satellite that sends data back to the Beijing control center, the space agency said in a posting late Friday on its website.  Chang'e 4, named after a Chinese moon goddess, is the first craft to make a soft landing on the moon's far side, which faces away from Earth. Previous landings, including one by China's Chang'e 3 in 2013, have been on the near side.

After sending the rover off from a ramp, the spacecraft deployed three 5-meter (16-foot) low-frequency radio antennas, the Chinese space agency said. Chang'e 4 also has sent back images taken with a topographical camera. Researchers hope that low-frequency observations of the cosmos from the far side, where radio signals from Earth are blocked by the moon, will help scientists learn more about the early days of the solar system and even the birth of the universe's first stars.

With regards – S. Sampathkumar
6th Jan 2019.
PS 1:   Chang'e is the Chinese goddess of the Moon. She is the subject of several legends in Chinese mythology.  Hou Yi the archer is her husband.  In modern times, Chang'e has been the namesake of the Chinese Lunar Exploration Program.  Hou Yi is a mythological Chinese archer.  He is sometimes portrayed as a god of archery descended from heaven to aid mankind.   In Chinese lore, when 10 Suns rose from Earth and scorched the fields, turning the world into a wasteland, Houyi shot down 9 of the 10 Suns, leaving the last one alive.

PS 2 : As part of human exploration of the Moon, numerous space missions have been undertaken to study Earth's natural satellite. Of the Moon landings; Luna 2 was the first spacecraft to reach its surface successfully, intentionally impacting the Moon on 13 September 1959. In 1966, Luna 9 became the first spacecraft to achieve a controlled soft landing, while Luna 10 became the first mission to enter orbit.  Between 1968 and 1972, manned missions to the Moon were conducted by the United States as part of the Apollo program. Apollo 8 was the first manned mission to enter orbit in December 1968, and was followed by Apollo 10 in May 1969. Six missions landed men on the Moon, beginning with Apollo 11 in July 1969, during which Neil Armstrong became the first man to walk on the Moon. Apollo 13 was intended to land, however it was restricted to a flyby due to a malfunction aboard the spacecraft. All nine manned missions returned safely to the Earth.

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