Lunar probe enters moon's orbit |
文章来源： 文章作者： 发布时间：2007-11-05 08:02 字体： [ 大 中 小] 进入论坛 |
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| Chang'e-I successfully completed its first braking at perilune and entered the moon's orbit Monday morning, becoming China's first circumlunar satellite. |
| Nov. 5 - China's first lunar probe, Chang'e-I, successfully completed its first braking at perilune and entered the moon's orbit Monday morning, becoming China's first circumlunar satellite.
Chang'e-I, following the instructions of the Beijing Aerospace2 Control Center (BACC), started braking at 11:15 a.m. at a position around 300 km away from the moon and entered the moon's orbit at around 11:37 a.m. after completing the braking, according to the BACC.
The braking was performed just in time to decelerate the probe, enabling it to be captured by the lunar gravity and become a "real" circumlunar satellite, said Wang Yejun, chief engineer of BACC.
"The first braking at perilune is a key moment in the long journey of Chang'e-I," Wang said.
The speed of Chang'e-I reached about 2.3 km per second when it started braking. It would likely fly away from the moon if the braking was too early, or it would crash into the moon if the braking was too late, scientists said.
After the braking, the probe's speed was slowed down to 1.948 km per second and is now traveling along a 12-hour elliptical moon orbit, with a perilune of about 200 km and an apolune of about 8,600 km.
"The orbit that Chang'e-I is now moving on fully1 tallies3 with the one we have designed and the speed is within a normal range," said Ji Gang, an engineer of monitoring and controlling branch of the moon probe program.
The probe is expected to brake for another two times in the following two days to further slow down to enter a round orbit, where it is supposed to start "working" formally.
Chang'e-I will then stay a year in the 127-minute round orbit, which is 200 km from the moon's surface, for scientific explorations.
China's first lunar probe, Chang'e-I, named after a legendary4 Chinese goddess who flew to the moon, blasted off on a Long March 3A carrier rocket on October 24 from the Xichang Satellite Launch Center in southwestern Sichuan Province.
The probe completed its fourth orbital transfer on October 31, which shifted it to the earth-moon transfer orbit and pushed it to fly to the moon "in a real sense".
It was previously5 moving around the earth and experienced three orbital transfers, which lifted it up first to a 16-hour orbit with an apogee6 of 50,000 km, then to a 24-hour orbit with an apogee of 70,000 km and next to a 48-hour orbit with an apogee of more than 120,000 km.
On November 2, BACC successfully carried out an orbital correction for Chang'e-I to ensure that it traveled on the pre-set orbit.
A second orbital correction scheduled for November 3 was called off because it was "unnecessary" -- Chang'e-I had been running accurately7 on the expected trajectory8, a BACC scientist said.
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点击  收听单词发音
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1
fully
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| adv.完全地，全部地，彻底地；充分地 |
参考例句： |
- The doctor asked me to breathe in,then to breathe out fully.医生让我先吸气，然后全部呼出。
- They soon became fully integrated into the local community.他们很快就完全融入了当地人的圈子。
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2
aerospace
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| adj.航空的，宇宙航行的 |
参考例句： |
- The world's entire aerospace industry is feeling the chill winds of recession.全世界的航空航天工业都感受到了经济衰退的寒意。
- Edward Murphy was an aerospace engineer for the US Army.爱德华·墨菲是一名美军的航宇工程师。
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3
tallies
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| n.账( tally的名词复数 )；符合；（计数的）签；标签v.计算，清点( tally的第三人称单数 )；加标签（或标记）于；（使）符合；（使）吻合 |
参考例句： |
- Cash on hand tallies with the figure in the accounts. 现款跟账上的数目没有出入。 来自《现代汉英综合大词典》
- He tallies his own marks. 他把自己的得分记了下来。 来自《简明英汉词典》
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4
legendary
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| adj.传奇（中）的，闻名遐迩的；n.传奇（文学） |
参考例句： |
- Legendary stories are passed down from parents to children.传奇故事是由父母传给孩子们的。
- Odysseus was a legendary Greek hero.奥狄修斯是传说中的希腊英雄。
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5
previously
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| adv.以前，先前（地） |
参考例句： |
- The bicycle tyre blew out at a previously damaged point.自行车胎在以前损坏过的地方又爆开了。
- Let me digress for a moment and explain what had happened previously.让我岔开一会儿，解释原先发生了什么。
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6
apogee
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| n.远地点；极点；顶点 |
参考例句： |
- The orbit of the artificial satellite has an apogee of 200 miles from the earth.这个人造卫星的轨道，其最远点在离地球200英里的地方。
- Apogean tides occur when the moon is at the apogee of its orbit.远月潮在月球位于其轨道的最远点时发生。
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7
accurately
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| adv.准确地，精确地 |
参考例句： |
- It is hard to hit the ball accurately.准确地击中球很难。
- Now scientists can forecast the weather accurately.现在科学家们能准确地预报天气。
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8
trajectory
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| n.弹道，轨道 |
参考例句： |
- It is not difficult to sketch the subsequent trajectory.很容易描绘出它们最终的轨迹。
- The path followed by a projectile is called its trajectory.抛物体所循的路径称为它的轨道。
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