2021-10-24

“Lost contact” for a month, tianwen-1 successfully passed the test

By yqqlm yqqlm

Visit: tmall’s double 11 red envelope receiving page in 2021 Jingdong’s 2021 double 11 “No. 1 Beijing Post” receiving entrance

at present, tianwen-1 surround device runs on the relay communication track, mainly for Zhu Rong. From late September to mid October 2021, Mars and the earth run to both sides of the sun, and the three are almost in a straight line. There is a solar eclipse phenomenon. Due to the interference of solar electromagnetic radiation, the vehicle ground communication is interrupted, the orbiter and the rover turn to safe mode and stop the exploration work. After the end of the solar eclipse, the orbiter chose an opportunity to enter the remote sensing mission orbit to carry out global remote sensing exploration of Mars, obtain scientific data such as Martian morphology and geological structure, surface material composition and soil type distribution, atmospheric ionosphere and Martian space environment, and take into account the relay communication in the expansion mission stage of the rover

“Lost contact” for a month, tianwen-1 successfully passed the test

before you care about whether tianwen-1 is well, you should first understand what is the sunburn phenomenon? In the traditional sense, riling is proposed for communication satellites. Communication satellites are generally located in geosynchronous orbit above the equator at an orbital altitude of 36000 km from the earth. At the spring equinox and autumn equinox every year, the sun shines directly at the equator of the earth. Therefore, from the earth, the sun coincides with the communication satellite. The sun is transmitting a large number of chaotic radio signals all the time, and the antenna we use to receive satellite signals will actually receive signals from the sun

“Lost contact” for a month, tianwen-1 successfully passed the test(1)

in front of the powerful sun, satellite signals are like candles. Although the current antenna pointing accuracy is very high, the radio signal from the sun will inevitably interfere with the signal of normal communication satellites, which will lead to abnormal ground reception. For example, the TV signal in our family will be unstable, with “snowflake” screen or blue screen

“Lost contact” for a month, tianwen-1 successfully passed the test(2)

when exploring Mars, the probe flies around Mars. From a macro point of view, the space position of the probe coincides with Mars. Then, when Mars is blocked by the sun, or completely submerged by sunlight, the probe will naturally be blocked by the sun. In astronomy, the phenomenon that Mars and the earth travel approximately 180 ° to both sides of the sun is called Martian solar conjunction. According to the law of the movement of celestial bodies in the solar system, tianwen-1 is in the stage of solar transit from late September to mid October this year

what is the impact of the solar eclipse on the Mars probe

at present, tianwen-1 is about 400 million kilometers away from the earth. Even if it flies at the speed of light, it will take more than 20 minutes to reach the position of the detector. Tianwen-1 detector is so far away from us that we can only know its state through radio signals. Before and after the closing of the sun on Mars, it is easy to have a solar eclipse. The connection between the probe and the earth will be significantly affected by the sun, and even the signal may be interrupted. Once the radio signal is interrupted, the ground will not be able to talk to tianwen-1, nor will it be able to command Zhu Rong to carry out scientific research and exploration. In short, the sun is a huge radiation source. When it appears on the communication link between our ground station and the detector, it will affect the communication. Therefore, tianwen-1 and zhurong lost contact for a month

How did Tianwen 1 spend the sunburn

during the sunburn, the ground knew nothing about the status of tianwen-1, which put forward higher requirements for the autonomous control ability of tianwen-1. Since the ground control personnel have accumulated data and experience on the on orbit state of the detector, the external environmental conditions experienced by the detector during “loss of contact” can be predicted. Secondly, the detector can take avoidance measures against possible risks. At the same time, according to the estimated environmental conditions, set the state of the relevant system of the detector before entering the sunburn, and adjust the state of the whole detector to a relatively simple and reliable “safety mode”. Finally, the detector has the ability of independent management. During the sunrise, the system on the detector shall be inspected regularly. If any abnormality is found, it will be handled independently according to the pre-determined plan to ensure that the detector can normally establish a communication link with the ground after sunrise

“Lost contact” for a month, tianwen-1 successfully passed the test(3)

in a word, Mars Exploration of solar eclipse is a natural phenomenon, and solar eclipse also accumulates some experience for planetary exploration technology. The tianwen-1 detector and zhurong not only make us more confident, but also make zhurong take a good holiday after more than 100 days of hard work, don’t you think? (Chu Yingzhi)

fully autonomous flight. Tianwen-1 successfully passed the test of riling

in September 2021, the news of “tianwen-1 will be lost for one month” swept through the circle of friends; A few days ago, the tianwen-1 Mars exploration mission team officially set the on-board status to “sunrise”, which marks that the Mars Orbiter has successfully completed its full autonomous flight for more than one month and successfully passed the sunrise test. The good news of Tianwen 1 not only makes everyone happy, but also makes many people wonder: what has Tianwen 1 experienced in more than a month? What on earth does it rely on to successfully complete its autonomous flight on distant Mars? Don’t worry, the tianwen-1 Mars Orbiter team of the eighth Academy of Aerospace Science and Technology Group will answer them one by one

the “Sunburst” in Mars exploration

Mars is far from the earth, and the distance between the two has been changing periodically between 55 million and 400 million kilometers. In order to realize the communication between Mars and the earth, all Mars probes need to adopt powerful communication technology and configure complex communication equipment. For example, the Mars Orbiter is equipped with a communication system composed of ultra-high sensitivity deep space transponder, 2.5m aperture directional antenna, complex microwave network and other equipment. However, even so, it can not resist the super strong electromagnetic radiation of the sun. When the sun is between Mars and the earth, the radio communication between the Mars probe and the earth will be disturbed and lost contact

“Lost contact” for a month, tianwen-1 successfully passed the test(4)

according to the motion law of celestial bodies, Mars and the earth will be separated on both sides of the sun every 26 months, and the three celestial bodies are approximately connected in a line. From mid September to late October 2021, all Mars probes working on Mars, including the United States, Europe and India, will lose contact with the ground during this period, including China’s tianwen-1 Mars Orbiter and zhurong Mars rover

the “solar transit mode” of tianwen-1 has been prepared for a long time

in order to ensure the safety of on orbit flight, the Mars Orbiter team adjusted the working mode of the Mars orbiter in mid September 2021. After completing the comprehensive status inspection, set the surround device to the independent safety steady-state management mode, i.e. “sunning mode” through the ground command to deal with the loss of contact between the device and the ground. During the solar transit, the ground receives telemetry of the status of the Mars Orbiter every day to determine the orbiting status of the orbiter and the interference of the sun to the communication between the orbiter and the ground

with the movement of the relative positions of Mars, the earth and the sun, the wireless communication of Mars orbiter to the earth has experienced the process of interference, interruption and gradual recovery. In mid October 2021, the vehicle ground communication was restored, and the mission team began the condition assessment of the Mars Orbiter. After careful analysis and confirmation, the Mars Orbiter is in good condition. Recently, the mission team officially set the status on the machine to “sunrise Ling” through the ground command. This indicates that the Mars Orbiter has successfully completed its full autonomous flight for more than one month and successfully passed the test of solar transit

the subsequent Mars orbiter will resume exploration, complete orbit adjustment and enter the orbit of scientific exploration mission. After entering the orbit of the scientific mission, the seven loads carried by the Mars Orbiter, including the medium resolution camera, the high resolution camera, the subsurface detection radar, the mineral spectrum analyzer, the magnetometer, the ion and neutral particle analyzer and the energy particle analyzer, will be powered on to carry out global and comprehensive scientific exploration of Mars

review of major nodes of tianwen-1:

on July 23, 2020, tianwen-1 was launched by the Long March 5 remote-4 carrier rocket at Wenchang space launch site, successfully entered the predetermined orbit and took the first step in China’s planetary exploration

on July 28, 2020, tianwen-1 looked back at the earth 1.2 million kilometers away from the earth, imaged the earth and the moon with an optical navigation sensor, and obtained a group photo of the earth and the moon. In this black-and-white group photo, the earth and the moon, large and small, are crescent shaped, watching each other in the vast universe

on August 2, 2020, tianwen-1 3000n engine started for 20 seconds, successfully completed the first orbit correction and continued to fly to Mars

on September 20, 2020, four 120N engines of tianwen-1 were started for 20 seconds at the same time, the second track correction was successfully completed, and all systems of the detector were in good condition

on October 1, 2020, NASA released the “deep space self photographing” flight image of tianwen-1, China’s first Mars exploration mission

on October 9, 2020, the main engine of tianwen-1 was ignited for more than 480 seconds, the deep space maneuver was successfully completed, and the detector systems were in good condition

on October 28, 2020, eight 25N engines of tianwen-1 were started at the same time, the third orbit correction was successfully completed, and the tracking of ground TT & C communication centers and stations was normal

on February 5, 2021, tianwen-1 engine ignited and completed the midway correction of the fourth orbit of the earth fire transfer section. NASA released the first image of Mars sent back by the probe simultaneously

on February 10, 2021, tianwen-1 was successfully captured by Mars and entered the annular fire orbit

on February 15, 2021, tianwen-1 orbiter implemented the plane maneuver of capturing the far fire point of the orbit, and the orbit height near the fire point was adjusted to about 265km

on February 24, 2021, tianwen-1 orbiter implemented the third approach fire braking and entered the parking track

on May 15, 2021, the tianwen-1 landing patrol successfully landed in the pre selected landing area in the south of the Martian Utopia plain, and China’s first Mars exploration mission landed on Mars successfully

on May 17, 2021, tianwen-1 orbiter implemented the fourth approach fire braking and entered the relay communication track

on June 11, 2021, the first batch of scientific images of tianwen-1 were released, marking the complete success of China’s first Mars exploration mission

from late September to mid October 2021, tianwen-1 is in the stage of solar transit