Tianwen No.1 successfully entered orbit! How difficult is it to “ask the heavens”? | Red Lei Feng

Last night, after almost 7 months of walking, my country’s first Mars exploration mission, Tianwen-1, finally entered the orbit of Mars as scheduled!

According to official sources of the China Space Administration:

At 7:52 p.m. on February 10, 2021, the Tianwen No. 1 detector implemented the near-fire capture brake. The 3000N orbital controlled orbital’s engine ran for about 15 minutes. The detector entered the near-fire point at an altitude of approximately 400 kilometers with a period of approximately One large elliptical orbit of fire with an inclination of approximately 10º in 10 Earth days.

Tianwen No.1 successfully entered orbit

Zhang Kejian, director of the National Space Administration and project commander of the Mars exploration mission, announced the success of orbiting Mars. So far, Tianwen-1 has become my country’s first man-made satellite of Mars, and its three-step plan of “orbit, orbit and patrol” has also been successfully launched.

Since the successful implementation of the capture of Mars last night, Tianwen-1 has flown for 202 days, with a flight mileage of approximately 475 million kilometers and a distance of approximately 192 million kilometers from Earth. All systems are in good condition.

Lei Feng.com found that after the transition from terrestrial fire to the capture stage of Mars, the medium resolution camera, the high resolution camera, the magnetometer, the mineral spectrum analyzer, the ion and neutral particles and the energy particles carried by Tianwen-1. Payloads such as probes will also begin to operate, and multidimensional exploration of Mars will also begin.

The National Space Administration stated:

Subsequently, Tianwen-1 will undergo various orbital adjustments, enter the mooring orbit of Mars and carry out a scan of the preselected landing zone. It is planned to choose an opportunity to land on Mars in May-June 2021 and conduct inspections.

In response, Thomas Zurbuchen, deputy director of NASA’s Science Mission, said on Twitter:

Today, Tianwen-1 successfully entered the orbit of Mars. Congratulations to China. There are still many unsolved mysteries on Mars waiting for us to explore, waiting for China’s achievements!

In addition to NASA, the European Space Agency also expressed its congratulations via Twitter.

As my country’s first Mars exploration mission, Tianwen-1 has garnered a lot of attention since its successful launch on July 23, 2020, and news of its successful orbit quickly made it to the major hot lists on social media.

Netizens said one after another:

The Power of Science and Technology! The New Years Gift Package is here!

Send my New Years greetings to Tianwen No.1, Happy New Year!

Chinese perspective, Chinese honor.

How difficult is Tianwen Mission No. 1?

Since the 1960s, Mars exploration has gone through the history of manned spaceflight, but to this day, the success rate of Mars exploration missions around the world is still less than 50%.

In October 1960, the former Soviet Union launched the first and second “Mars 1A” and “Mars 1B” probes, but they did not even reach Earth orbit.

Since then, the probes of the former Soviet Union and the United States have not been launched, have lost communication or have burned out. Many attempts have failed.

In 1964, the spell of failure was broken for the first time. The US Mariner 4, launched on December 28, finally passed over Mars 9,800 kilometers from the surface of Mars 7 months later and sent 21 photos back to Earth. This is the first time in history that it successfully reached Mars and sent it back. Data detector.

It was in the 1970s that the Mars rover (the American “Sailor 9”) entered orbit around Mars for the first time.

Since then, Japan, the European Space Agency, India, the United Arab Emirates, and China have joined the Mars exploration team. Humans have launched spaceships to Mars about 50 times; however, there are 11 missions without breaking Earth’s range of gravity, and 5. The detector lost contact in the middle.

It is understood that there are four main types of Mars exploration missions: one is a simple flyby, which is used mainly in the immature stage of aerospace technology; the other is in orbit, the probe decelerates to the orbit of Mars when braking; the third is landing, on Mars. The surface is studied in detail, the fourth is patrol, the rover will carry a series of scientific instruments to patrol for free.

[La fuente de la imagen conoce la respuesta al @Space Craft principal]

What Tianwen-1 has to do is complete the circumnavigation-landing-patrol mission in one go. Considering the previous situation of several countries in the exploration of Mars, the difficulty is evident.

Previously, Leifeng.com reported thatThe difficulty of this task lies in the following aspects:

First of all, even in the window period, Mars remains a distant planet. The probe carries limited fuel to travel far, placing great demands on the precise design of the probe’s flight orbit.

Second, if the probe successfully enters the orbit of Mars after a long journey of 6 to 7 months, whether it can be captured by Mars is also a great difficulty. The distance from the entry point directly affects whether the probe is captured or passed Mars or crashed.

Third, the biggest challenge of the entire mission is how to successfully land on Mars. It takes about 7 minutes for the detector to slow down from 4.8 km / s to 0, and this process is often referred to as “7 minutes of terror”. When to reduce the speed, attitude and angle of entry into the atmosphere, everything must be precisely controlled, but in view of the lack of human knowledge of Mars and the delay of one-way radio signals between earth and fire, it is not easy. . trust the ground command.

Fortunately, Tianwen No.1 has overcome two major problems.

What needs to be explained here is that the key to the fact that Tianwen No. 1 was captured by Mars last night was a braking action.

According to the law of conservation of mechanical energy, to visit Mars, the mechanical energy of the “outer” Tianwen-1 is greater than 0, but only by reducing the mechanical energy can Tianwen-1 go into orbit, otherwise it can fly for Mars.

According to the Institute of Geology and Earth Sciences of the Chinese Academy of Sciences, in this case only aircraft brake operations can be performed:

There are two main braking methods for spacecraft today: one is the use of planetary atmospheric drag and aerodynamic “atmospheric braking”, and the other is the use of reverse propulsion braking using rocket engines.

This time, Tianwen No.1 adopted the latter. On the one hand, Tianwen No.1 is divided into two parts: the orbiter and the lander (patrol device). The orbiter must remain in the stable orbit of Mars for a long time. and they can’t stop all at once. On the other hand, my country has very little knowledge of the Martian atmospheric environment, including density distribution, temperature distribution, wind field, etc. The data provided by the United States in public documents is not detailed enough to be credulous.

It is understood that in addition to the first ignition last night, Tianwen-1 will also ensure that it is in the orbit of Mars through two ignitions.

The following figure shows the initial plan of the Tianwen-1 orbital maneuver.

Next, Tianwen-1 will analyze the topography, atmospheric features, wind speed, weather, and other features of Mars through its own science instruments as it races around Mars. After about 100 days, it will lower its orbit. Launch the lander.

In other words, we should hear the good news that Tianwen-1 has officially landed on Mars!

China is among the “ Martian countries ”

For China, February 11, 2021 is not just a 29th ordinary month of the 12th lunar month, it is the day that China is among the “Martian countries.”

As early as January 11, 2016, China’s Mars exploration mission was officially established, planting the seeds for the idea of ​​launching a probe to Mars around 2020.

Since then, my country’s Mars exploration mission has progressed smoothly as planned:

• In October 2019, the Chinese Mars Rover was unveiled.

• In November 2019, China’s Mars exploration mission was made public for the first time.

• On April 24, 2020, the fifth “China Space Day”, the National Space Administration officially announced that my country’s planetary exploration mission was called “Tianwen” and my country’s first Mars exploration mission was called “Tianwen-1”.

• At 12:41 on July 23, 2020, the Long March 5 Yaosi carrier rocket carrying “Tianwen-1” was successfully launched at the Wenchang space launch site in Hainan, and the first Mars exploration mission was launched. from my country.

• On July 27, 2020, ground personnel controlled Tianwen-1 as it flew about 1.2 million kilometers from the earth to look back and get a photo of the earth and the moon.

• At 07:00 on August 2, 2020, under the control of the flight control team, Tianwen-1 completed the first intermediate correction of its orbit.

• On August 28, 2020, Tianwen-1 has been in orbit for 36 days and the flight course has exceeded 100 million kilometers.

• At 11:00 p.m. on September 20, 2020, under the control of the flight control team, Tianwen-1 completed the second intermediate correction of its orbit.

• On October 1, 2020, National Day, the China National Space Administration released the first “self-portrait” of the Tianwen-1 deep space and national flag.

• At 23:00 on October 9, 2020, under the control of the flight control team, Tianwen-1 completed a maneuver in deep space.

• At 10:00 p.m. on October 28, 2020, under the control of the flight control team, Tianwen-1 completed the third intermediate correction of its orbit.

• As of November 17, 2020, Tianwen-1 has been in orbit for 116 days, with a flight mileage of more than 300 million kilometers.

• On January 3, 2021, Tianwen-1 was in orbit for 163 days, with a flight mileage of more than 400 million kilometers.

• At 20 o’clock on February 5, 2021, Tianwen-1 completed the fourth intermediate correction of its orbit and returned the first Martian image taken at a distance of about 2.2 million kilometers from Mars.

Finally, my country’s first Mars exploration mission has successfully entered the capture phase of Mars from the ground fire transfer phase!

Last night, CCTV officially announced the 2021 Year of the Ox Spring Festival Gala program. There was a special program called “Report to the Fatherland” in the program list, Tianwen No. 1 master design, Chang’e No 5, Shenzhou Spaceship and Beidou No. 3 The teacher and other guests will appear in front of the camera. On the eve of the ox in the lunar calendar, the story of Tianwen No.1 will definitely add a special sense of ceremony to the festival.

Finally, I wish you a happy Chinese New Year.

Reference source:

http://www.cnsa.gov.cn/n6758823/n6758838/c6811243/content.html

https://mp.weixin.qq.com/s/cOjTEu4-PLUmk8UEKRbUTg

https://www.zhihu.com/question/443835163

Lei feng(Public account: Leifeng.com)Red Lei Feng Red Lei Feng

Reproduction of original Leifeng.com articles is not permitted without authorization. See reprint instructions for details.