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The author:(作者)aaa
published in(发表于) 2013/12/6 12:19:47
Chang-third has arrived near the Moon， upcoming brake-Chang third in recent months-the Moon

Beijing authorities wide nets, December 6 (Xinhua Zhang Mian Mian), according to voice of the press reported the evening peak, its plans to become immortal, near the third probe, has now reached the Moon, soon to be implemented in recent months brakes, complete a "space brake" action.

According to Chang-space technologies Research Institute of aerospace science and Technology Corporation, third expert Wu Xueying detector system introduced to become immortal, the third probe, after two successive amendments in the Middle, at present, the flight in good condition. Now Chang the third probe, have been running is about more than 110 hours flying around 350,000 kilometers, with braking conditions in recent months.

In recent months, the so-called brake, simply put, is when flying satellites or probes to the Moon is near a speed greater than the Moon's 2.38 km/s relative to the Moon's escape velocity, if you don't slow down, satellite, or probe will fly away from the moon. To achieve a lunar flight, braking is necessary, will reduce its speed to escape velocity of the Moon, which was the Moon's gravity to capture it. Braking is flying satellites or probes in recent months during one of the most critical orbit control.

By Yu Change braking mode with Chang in recent months, first, third, second, different, 7500N with variable thrust engine, ignition can achieve lunar orbit only once, while Chang, first, second, use 490N engine ignition brake also made available through steps to achieve lunar orbit. 7500N engines and precise monitoring and control has become a bright spot and difficult.

Once the brake successfully in recent months, Chang-third scientific exploration activities in Lunar soft landing has laid a solid foundation. At the same time, also suggests that the Moon, satellites and probes for accurate measurement and control capabilities will be greatly enhanced, signs in space and control level, there is a new breakthrough.

Wu Xueying: problems, precision is the key, brake if there were fewer, the detector will miss the Moon, and cannot be captured by the moon. If the braking is too large, the probe would crash into the moon. So accurate brake is the most critical in recent months, the track measured to calculate accurate, detectors, control parameters also to perform certain, that any one problem which could lead to failure.

(Original title: experts say Chang, third flight in good condition has had in recent months, braking conditions)

　　央广网北京12月6日消息 (记者张棉棉)据中国之声《新闻晚高峰》报道，按照计划，嫦娥三号探测器目前已经到达月球附近，即将实施近月制动，完成一次“太空刹车”动作。

　　据航天科技集团公司空间技术研究院嫦娥三号探测器系统专家吴学英介绍，嫦娥三号探测器经过接连两次中途状态修正，目前，飞行状态良好。现在，嫦娥三号探测器已正常运行约110多个小时，飞行35万公里左右，具备近月制动的条件。

　　所谓近月制动，简单地说，就是当卫星或探测器飞行到月球附近时，相对月球的速度大于月球2.38公里/秒的逃逸速度，如果不减速，卫星或探测器将飞离月球。要实现绕月飞行，必须进行制动，将其飞行速度降低到月球逃逸速度以内，从而被月球引力捕获。近月制动是卫星或探测器飞行过程中最关键的一次轨道控制。

　　由于嫦娥三号的近月制动方式与嫦娥一号、二号不同，采用变推力的7500N发动机，只一次点火就实现环月圆轨道飞行，而嫦娥一号、二号都使用490N发动机通过点火制动才分步实现环月圆轨道飞行。而对这7500N的发动机的精准测控也就成为一个亮点和难点。

　　一旦这次近月制动成功，为嫦娥三号在月面软着陆 进行科学探测活动奠定了坚实基础。同时，也表明我国对月球卫星和探测器进行精确测控的能力将大大增强，标志我国航天测控水平有了新突破。

　　吴学英：难点最关键在于精准，制动量如果少了，探测器会与月球擦肩而过，不能被月球捕获。如果制动量过大，探测器就会与月球相撞。所以近月制动最关键的就是精准，轨道要测得准、控制参数要计算得准、探测器也要执行得准，这其中任何一个环节出问题都可能导致失败。

(原标题：专家称嫦娥三号飞行状态良好 已具备近月制动条件)

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