“天问一号”火星探测器完成第一次轨道修正

8月2日7时0分，我国首次火星探测任务“天问一号”探测器3000N发动机工作20秒钟，顺利完成第一次轨道中途修正，继续飞向火星。

The probe of China's first Mars mission, Tianwen-1, successfully carried out its first orbital correction Sunday morning, according to the China National Space Administration.

The probe completed the orbital correction at 7 a.m. Beijing time after its 3000N engine worked for 20 seconds.

It had flown for about 230 hours in space, traveling 3 million kilometers away from the Earth by the time of the first orbital correction.

在驶向火星的七个月当中，天问将进行四次左右轨道修正，航天科技集团五院火星探测器系统产品保证经理饶炜告诉记者。

“今天是整个推进系统第一次真实的在轨表现，和我们的预期很接近。表现良好。”饶炜告诉记者，“探测器轨控的状态要靠第一次作为标定，以后会越来越逼近。”

"This is the first real demonstration of the propelling system's performance in space. And it did well," said Rao Wei of China Aerospace Science and Technology Corporation. 

"The result of the first correction sets an anchor and starting point for the rest of other orbit adjustments," he added. 

Tianwen-1 will adjust courses for around four times during its seven-month journey to Mars, according to Rao. 

国家航天局探月与航天工程中心深空探测总体部部长耿言说，“修正幅度很小，因为火箭打得很准所以修正的幅度很小。”

“这一次中途修正也很重要的是，在轨标定轨控发动机，也就是3000N发动机的性能，这也是它第一次上天开机，这是今天两方面的意义。”

Geng Yan from the Lunar Exploration and Space Engineering Center at CNSA said all of the systems have been in good condition. 

"The adjustment was very minor. That's because the rocket launch had been accurate," Geng told CGTN. 

"This mid-course correction is also significant in that this is the first time we have the on-orbit calibration engine, the 3000N engine, activated in space," he added.

我国首次火星任务“天问一号”探测器7月23日顺利升空，迈出了我国自主开展行星探测的第一步。

China launched its first Mars mission Tianwen-1, which means "Questions to Heaven," on July 23, marking the country's first step in planetary exploration of the solar system.

The probe took a photo of the Earth and the Moon at a distance of 1.2 million kilometers away on Monday.

The probe will undergo deep space maneuvers and several mid-course corrections before reaching Mars. /CCTV

Why conduct orbital correction?

据专家介绍，现在很多汽车都具有车道保持功能，如果车偏离了自己的车道，就会自动修正方向，让车回到原本的车道上来。火星探测器的轨道修正与之类似，但不同的是火星探测器要修正的不仅仅是飞行方向，还有飞行速度等多个变量。而在茫茫太空中，探测器也没有道路标线作为参照物，因此难度很大。

Similar to the lane keeping aid, known as LKA, for vehicles, orbital correction ensures the Mars probe travels along the planned orbit.

But the Mars probe has to correct not only the flight direction but also other variables, such as its flight speed. The probe also has no road markings as a reference in space, making the process much more difficult.

在地火转移轨道飞行过程中，探测器会受到入轨偏差、控制精度偏差等因素影响。由于探测器长时间处于无动力飞行，微小的位置速度误差会逐渐累积和放大，如果不进行修正，将使探测器错过火星，导致“差之毫厘，谬以千里”的严重后果。因此执行飞行任务时，需要制定地火转移轨迹中途修正控制策略，包括每次修正的时机、每次修正速度增量大小及速度增量方向。实际任务中，科研人员需要根据中途修正策略完成对应的探测器姿态和轨道控制，确保探测器始终飞行在预定的轨道上。

During the Earth-Mars transfer orbit, the probe will be affected by the deviation of orbit entry and control accuracy. As the flight is mostly unpowered and lasts a long time, the tiny inaccuracies in position and velocity will gradually accumulate, and cause the probe to miss the red planet if not corrected.

Therefore, a control strategy for mid-course orbital correction is indispensable, as it sets the time, speed increment and the direction of each correction.

据了解，此前本次长征五号运载火箭精准地将火星探测器送入了预定轨道，使得这次轨道控制的主要目标不再是入轨精度修正，而是要完成轨道控制3000N主发动机的第一次工作和在轨标定，此后还将根据探测器实际飞行状态，利用中途修正对发动机的推力和方向等持续标定，迭代优化中途修正策略，最终保证探测器能够准确地进入火星捕获走廊。

Researchers for the flight mission need to conduct the corresponding attitude and orbital control of the probe according to the strategy to ensure that the probe always flies in the predetermined orbit.

The correction strategy will also be continually optimized according to the flight status of the probe.

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