Posts Tagged ‘Lunar exploration’

Chinese Jade Bunny took off for the moon tonight

December 1, 2013

UPDATE!! 1st December 2013 2030 GMT

Xinhua: The probe’s carrier, an enhanced Long March-3B rocket, blasted off from the Xichang Satellite Launch Center in southwest China at 1:30 a.m. Chang’e-3 is expected to land on the moon in mid-December to become China’s first spacecraft to soft land on the surface of an extraterrestrial body.

It is also the first moon lander launched in the 21st century. The probe entered the earth-moon transfer orbit as scheduled, with a perigee of 200 kilometers and apogee of 380,000 kilometers. “The probe has already entered the designated orbit,” said Zhang Zhenzhong, director of the launch center in Xichang. “I now announce the launch was successful.”

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Various Xinhua reports

China will launch the Chang’e-3 lunar probe to the moon at 1:30 a.m. Monday from Xichang Satellite Launch Center, The Chang’e-3 programme encompasses a lander and a moon rover called “Yutu” (Jade Rabbit). The Chang’e-3 mission is the second phase of China’s lunar program, which includes orbiting, landing and returning to Earth. It follows the success of the Chang’e-1 and Chang’e-2 missions in 2007 and 2010.

Artist's conception of the Chinese moon rover, called Yutu. Credit: CNSA

Artist’s conception of the Chinese moon rover, called Yutu. Credit: CNSA

The probe will be launched to orbit aboard an enhanced Long March-3B carrier which is more than three meters in diameter and 56.4 meters high. The mission will be the 25th launch of the Long March-3B, which is the most powerful launch vehicle in the Long March fleet.

After entering lunar orbit, Chang’e-3 will go through six stages of deceleration to descend from 15 km above to the lunar surface. The soft-landing processes of the U.S. and former Soviet Union’s unmanned spacecraft had no capacity to hover or avoid obstacles. Chang’e-3, on the other hand, can accurately survey landforms at the landing site and identify the safest spots on which to land.

In order to land quickly, the probe is equipped with high-precision, fast-response sensors to analyze its motion and surroundings. The variable thrust engine (completely designed and made by Chinese scientists) can generate up to 7,500 newtons of thrust.

But the real story I like of Chang’e and her Hou Yi and the reincarnation of Hou Yi as a Jade Bunny is this one from Over A Cuppa Tea. A Jade Bunny is much more evocative than a Jade Rabbit. Chang Er is perhaps a better phonetic rendition of Chang’e.

Once upon a time, there live two immortals in the Heaven, they are Hou Yi and Chang Er. Hou yi and Chang Er were lovers who goes through great obstacle before their love is approved by the Heaven.

The Heaven was ruled by the Jade Emperor and his Empress. One day, ten sons of Jade emperor accidentally transformed into the sun, and revolves around the earth playfully, causing great drought and suffering to the mortals below.

Worried and concern for the mortals, the Jade emperor summons the imperial archer, Hou Yi to help him solve the problem. Hou Yi then went to Earth and shot down nine of the Jade Emperor’s sons. The emperor had thought that Hou Yi would not harm any of his sons. Now that his sons are dead, the emperor was very furious. In anger, the emperor took away Hou Yi and his wife’s immortality and condemn them to live on Earth forever.

Chang*e and her jade bunny on the moon

Chang Er was grief stricken with her loss of immortality. Hou Yi could not bear to see his saddened wife, and so, he decided to steal the immortality pill from the heavenly medicine manufacturer so that both of their immortality could be restored. He manage to steal the pill from heaven, and brought it to Chang Er. He told her that they only need to take half of the pills to regain immortality.

In the meantime, the Jade Emperor found out about the stolen immortality pill, and command an imperial guard to retrieve the pills and catch both Hou Yi and Chang Er so that he could punish them for their misdeed.

And so, the imperial guard went down to earth in pursuit of the couple and the pill of immortality. But the guard himself was tempted by the idea of immortality. So he waited until Hou Yi is not at home, and attacked Chang Er who is defenseless at home. He demanded for the pill but Chang Er refused to hand it to him. Hou Yi, who seems to forget his arrows went back home to get it and discovered that his wife is in danger. He fought the imperial guard courageously.

Unfortunately, Hou Yi is an archer, not a fighter. He was stabbed right in his heart in front of Chang Er. Chang Er was grief stricken, and wishes to die with her husband too. However, Hou Yi’s dying wish was for Chang Er to regain her immortality and live happily for all eternity.

So, Chang Er took out the pill from her sleeves and swallowed the whole pill so that the guard would not be able to get it and obtain immortality. Right after swallowing the pill, Chang Er started to float towards the sky, and after flying for some time, she landed on the moon. She cried and grieve for her husband’s death.

Her cries was heard by a group of Jade Bunnies that lives on the moon. They went to her and listened to her story. These Jade Bunnies were captivated by Chang Er’s beauty and kindness towards them, so they built a palace for her to stay, knowing that she could never return to Heaven or Earth. They hailed her as their goddess and pledge allegiance to her. These bunnies can be seen pounding on the face of the moon on some cooking utensil.

It is believed that these Jade Bunnies are trying to make resurrection pills so that they could revive their Goddess’s love. It’s said that the resurrection pills is shaped like a mooncake. But it’s not dictate anywhere on whether Hou Yi was revived or not, but in many folklore, it’s told that Chang Er would bestow blessing of love and happiness to lovers who pray hard and sincere enough to the moon during mid-autumn.

According to my husband, however, there’s only one Jade Bunny on the moon, and it’s actually the reincarnation of Chang Er’s husband. He told me that the Jade Empress took pity on the couple, and so reincarnate Hou Yi as a Jade Bunny so that Chang Er will not be lonely on the moon. That explains why Chang Er can always be seen with a bunny everywhere she goes on the moon.

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Chang’e 2 is now “liberated” from earth and lunar gravity

September 11, 2011

China’s lunar probe Chang’e 2 completed its mission orbiting the moon three months ago and has now reached Lagrange (liberation) Point L2.

It has now reached a point in space where neither the moon nor the earth’s gravity will affect the probe. This point is called L2. It’s the farthest a Chinese spacecraft has ever been.

Chang’e 2’s primary mission was to orbit the moon at only 100 kilometers from the surface, taking high resolution photos. After completing this, scientists decided that there was enough fuel to continue with the second part of the mission. But sending the probe from the moon was unprecedented. Similar missions has previously left directly from Earth, so keeping the satellite on course was a technological challenge.

Zhou Jianliang, Deputy Chief Designer, Measure & Control System of Chang’e 2, said, “The satellite faced various disruptions on its journey, which could have led it off course. We had planned four readjustments to keep it on track. But we only need(ed) to do it once since the first adjustment proved so accurate.”

China’s ambitious three-stage moon mission is steadily advancing. The next phase will be the launch of Chang’e-3 in 2013. The probe’s mission is to land on the moon together with a moon rover. In the third phase, the rover should land on the moon and return to Earth with lunar soil and stones for scientists to study. The Chang’e program was named after the legendary Chinese goddess who flew to the moon. With the progress in technology and experience from the Chang’e mission, sending a Chinese astronaut to the moon is now clearly feasible.

On Lagrange Points:

The Italian-French mathematician Joseph-Louis Lagrange discovered five special points in the vicinity of two orbiting masses where a third, smaller mass can orbit at a fixed distance from the larger masses. More precisely, the Lagrange Points mark positions where the gravitational pull of the two large masses precisely equals the centripetal force required to rotate with them. Those with a mathematical flair can follow this link to a derivation of Lagrange’s result (168K PDF file, 8 pages).

Of the five Lagrange points, three are unstable and two are stable. The unstable Lagrange points – labeled L1, L2 and L3 – lie along the line connecting the two large masses. The stable Lagrange points – labeled L4 and L5 – form the apex of two equilateral triangles that have the large masses at their vertices.

Lagrange Points

Lagrange Points of the Earth-Sun system (not drawn to scale!): NASA

 The easiest way to see how Lagrange made his discovery is to adopt a frame of reference that rotates with the system. The forces exerted on a body at rest in this frame can be derived from an effective potential in much the same way that wind speeds can be inferred from a weather map. The forces are strongest when the contours of the effective potential are closest together and weakest when the contours are far apart. In the contour plot below we see that L4 and L5 correspond to hilltops and L1, L2 and L3 correspond to saddles (i.e. points where the potential is curving up in one direction and down in the other).

Effective Potential

A contour plot of the effective potential (not drawn to scale!): NASA

Flight accuracy gives Chang’e-2 new options

October 14, 2010

 

Chang'e flies to the moon.

Chang'e flies to the moon: Image via Wikipedia

 

After requiring only one course correction en route to the moon the fuel left on board Chang’e-2 keeps open all its future options after it completes its 6 month mission. Since Chang’e-1 was already crashed intentionally onto the moon, a return to earth or a flight into outer space are more likely than another descent to the moon’s surface. If the instruments remain in working order a continued flight past other targets in space could be more rewarding than a tame return to Earth.

Xinhua reports:

Chang’e-2 was carried into lunar orbit by a rocket, and only corrected once during the transfer from earth orbit to lunar orbit, so a large amount of fuel will be left after its mission, Zhou Jianliang, the vice chief-designer of BACC, said.

It is s expected to have enough fuel to fly back to earth, the vice chief-designer of the Beijing Aerospace Control Center (BACC) said Tuesday.

Zhou said there are three possible “fates” for Chang’e-2 after it finishes its six-month mission: landing on the moon; flying to outer space; or returning to earth. The fate of Chang’e-2 will be decided according to its condition when the mission is complete.

The Long March-3C carrier rocket took Chang’e-2 into space from southwest China on Oct. 1. The probe completed its final braking on Oct. 9 and is now orbiting the moon at a 100 km-high orbit.

Chang’e-2 mission on track

October 3, 2010

Chang'e programme: Xinhua

On Saturday scientists successfully activated the attitude control engines on Chang’e-2 and trimmed the satellite for the first time on its journey, according to a flight control official in Beijing. “During Chang’e-2’s 380,000-km journey to the moon, we will conduct more orbit corrections if necessary to ensure that it enters a lunar orbit,” said Ma Yongping, vice director of the flight control center. Chang’e-2 blasted off on a Long-March-3C carrier rocket from the Xichang Satellite Launch Center, in southwest China’s Sichuan Province, at about 7 p.m. Friday. It is China’s first unmanned spacecraft to be boosted from the launch site directly to the earth-moon transfer orbit, greatly reducing the journey time from that of its predecessor Chang’e-1.

Chang’e-1 took about 13 days to travel to a lunar orbit after orbiting the earth in a geosynchronous orbit and then transferring to the earth-moon transfer orbit. Chang’e-2 is expected to travel for about 112 hours, or almost five days, to arrive in a lunar orbit. To acquire more detailed moon data, Chang’e-2 will enter a lower lunar orbit about 100 km above the surface, compared with the 200-km altitude of Chang’e-1, according to the control center.

Sinus Iridum - Bay of Rainbows

The satellite will eventually be maneuvered into an orbit just 15 kilometer above the moon. At that point, Chang’e-2 will take pictures of moon’s Bay of Rainbows (Sinus Iridum)  area, the proposed landing ground for Chang’e-3, with a resolution of 1.5 meters. The resolution on Chang’e-1’s camera was 120 meters, said Wu Weiren, chief designer of China’s lunar orbiter project.


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