天文一号成功发射，开启中国自主火星探测第一步

周四中国在海南岛文昌航天发射场，用长征五号遥四运载火箭将我国首次火星探测任务“天问一号”探测器发射升空，开启了我国自主开展行星探测的第一步。
China launched its first independent Mars mission on Thursday from the Wenchang Space Launch Center in Hainan province, marking the start of the nation's planetary exploration program.

 

As the launch sequence started at 12:41 pm, 10 engines at the bottom of the Long March 5 carrier rocket's first core stage and four boosters roared to life, generating a combined thrust of more than 1,000 metric tons to lift the gigantic vehicle and its payload, the Tianwen 1 robotic probe, into a bright blue sky dotted with white clouds from the coastal¹ launch complex in Wenchang.

 

The 57-meter rocket, the strongest and most technologically² sophisticated in China's launch vehicle family, flew for more than half an hour before placing the spacecraft on an Earth-Mars transfer trajectory³. The flight set a speed record for the country's rocket fleet as it surpassed the escape velocity⁴ of 11.2 kilometers per second required to get away from Earth's gravitational pull.

 

If everything goes according to schedule, the 5-metric ton Tianwen 1, which consists of two major parts — an orbiter and a landing capsule — will travel more than 400 million kilometers in nearly seven months before getting captured by the Martian gravitational field, the China National Space Administration said.

 

Several mid-course and deep-space correction maneuvers⁵ will be made during the spaceflight to make sure the probe is precisely⁶ aimed at the red planet.

 

After the probe enters Mars orbit, it will revolve⁷ around the planet for two to three months to investigate the landing capsule's preset landing site before descending⁸ to release the landing capsule, which will gradually drop through the Martian atmosphere.

 

During the entry, descent and landing process, the capsule will first use a heat shield to decelerate, which means the craft will rely on aerodynamic drag to slow itself down. It will then deploy⁹ a parachute to further reduce the speed and drop its heat shield and later its back shell. In the next step, the capsule will drop the parachute and ignite its retrorockets.

 

When the craft reaches about 100 meters above the surface, it will suspend the descent and spend some time observing and analyzing¹⁰ the selected landing point to check for obstacles like rocks. With a positive result, the lander will continue descending until the last moment, when the retrorockets will be shut down, allowing it to touch down steadily¹¹ on Martian soil, according to the administration.

 

Meanwhile, the orbiter will continue circling the red planet for mapping and measurement tasks with seven scientific apparatus¹², including a high-resolution imager and a magnetometer. It will also relay signals between ground control and the rover.

 

 

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