The reporter, learned from the China National Space Administration that, according to signals sent back by the "Zhurong" Mars rover, the scientific research team confirmed that at 7:18 on May 15, the Tianwen-1's rover successfully landed at the pre-selected area in Utopia Planitia on Mars, marking the China's first Mars exploration mission a complete success.
On behalf of the Communist Party of China (CPC) Central Committee, the State Council and the Central Military Commission (CMC), Chinese President Xi Jinping, also general secretary of the CPC Central Committee and chairman of the CMC, extended warm congratulations and sincere greetings to all members who have participated in the Mars exploration mission, in a congratulatory message.
Xi said in the message that the landing marks an important step in China's interstellar exploration and a leap from the exploration of the Earth-Moon system to interplanetary exploration. "The landing left a Chinese mark on Mars for the first time. It is another landmark progress in China's space industry development. Thanks to your courage in face of challenges and pursuit of excellence, China is now among the leading countries in planetary exploration. The country and people will always remember your outstanding achievements."
Xi stressed organizing and implementing the roving and scientific exploration on Mars carefully, adhering to the self-reliance in sci-tech development, and pushing forward major space projects including planetary exploration. He also called for boosting China's strength in space technology and making new and greater contributions to exploring the mysteries of the universe and promoting the noble cause of peace and development of humanity.
The phased-array sensors, high-performance crystal components and electrical connectors, nano aerogel materials, accelerometers, unlocking separation devices and other series of products developed and produced by CASIC have made important contributions to the Mars orbiting, landing and roving exploration by Tianwen-1.
China's phased-array sensor first debut in outer space
The Tianwen-1 Mars probe completed Mars orbiting, landing and roving in single mission, of which the probe landing is a key part of this Mars exploration mission. The phased-array sensor independently developed by the 25 Research Institute, the CASIC Second Academy completed the first measurement for planetary landing and played a key role in the landing of Tianwen-1 rover on the Mars.
The phased-array sensor can accurately measure the distance and speed of the probe relative to the surface of Mars, and is used for lander engine deceleration, hovering and soft-landing control to ensure a smooth landing of the probe on the surface of Mars.
The characteristics of the deep space exploration mission determine that Mars probe have to work for long time, thus posing extremely demanding requirements on its self weight and volume. The microwave radar developed by CASIC has successfully completed successive space rendezvous and docking missions. The development team of this mission actively explored new areas of space exploration, and independently developed phased-array sensor with outstanding technical advantages in system integration and measurement system, which fully meet the requirements on miniaturization and integration of space products.
At present, the landing radar commonly used internationally requires multiple radar antennas to achieve measurement in different directions, while the phased-array sensor used in this mission only need one set of antennas to achieve accurate measurement in any direction within 120° field of view, which greatly reduces the weight and volume of the product. Previously, the development team carried out a series of ground tests to simulate the landform and climate on the Mars to fully validate the accuracy and reliability of the phased-array sensor working under different lighting, temperature, dust and other conditions on Mars.
"Customized design", ensuring the smooth landing of Tianwen-1
The use of deceleration parachute is one of the key aspects to ensure a smooth landing of the probe, and repeated tests need to be conducted for verification in the pre-mission preparation. The "customized" rocket guidance module developed by the Third Academy of CASIC successfully controlled the four test rockets to the preset altitude, velocity and attitude angle window, effectively verifying the indicators of the probe landing parachute. It is reported that the three independently developed integrated test rocket guidance modules achieved accurate and stable control of rocket attitude during the initial launch phase and flight altitude above 30km.
The accelerometer developed by the 33 Research Institute, Third Academy of CASIC of the Tianwen-1 can provide accurate acceleration measurement information to help the real time capture of speed, position and other information by the landing rover to ensure the accuracy of the landing rover GNC (guidance navigation and control subsystem) autonomous inertial navigation, providing an important prerequisite for a smooth landing.
During the landing process of Tianwen-1, the orbiter and landing rover need to be separated, and after the landing, the landing platform needs to release the rover; each step needs "customized" unlocking device. Factory 111 of the Third Academy of CASIC has developed six pieces of equipment for this mission, including the rover and lander connection and unlocking device, the back shield connection and unlocking device, the bottom connection and separation device, and the connection and unlocking device of the Mars rover. These key components realize the connection and unlocking and separation functions of the landing rover and the orbiter, and complete the unlocking and separation of the Mars rover and the lander after landing.
Protect the stable and safe operation of Tianwen-1
Due to the huge variations of the exploration environment, Tianwen-1 need to go through extremely high and low temperatures, therefore, the Third Academy of CASIC developed two types of high-performance nano aerogel materials with efficient cold and heat insulation to protect Tianwen-1 Mars exploration mission. The ultra-low density nano aerogel insulation board is used to block the extremely cold down to -120°C on the Mars surface. The density of this ultra-lightweight material is only one-tenth of the conventional aerogel material, which can effectively reduce the load of Mars rover. High temperature resistant nano aerogel insulation components are used to block the high temperature heat flow up to 1200°C generated by the landing engine and protect the normal function of the landing platform.
203 Research Institute, the CASIC Second Academy has developed and produced a series of crystal components for the communication system, guidance system and control system of Tianwen-1. Although small in size, crystal components can provide stable frequency signals for electronic devices, and are therefore often referred to as the "heart" of electronic devices. The crystal components developed and produced by 203 Research Institute are characterized by high reliability, excellent performance and good environmental adaptability, which can well meet the needs of long-duration flight of the probe in space.
304 Research Institute, the Third Academy of CASIC was responsible for the software testing of ground application system receiving and processing Mars exploration data, ensuring sound signal receiving software for Tianwen-1. The Mars exploration mission analysis and evaluation system developed by the 304 Research Institute provided quantitative analysis means for the scheme design, process simulation and result evaluation of the overall TT&C system, and effectively supported its iterative optimization.
More than 6,000 (sets of) connectors and relays used in this Mars exploration mission for signal transmission, signal control and signal on/off in the relevant system, working as the "nerve hub" of the electrical signal transmission system, were developed and produced by the GSA under AJG. Probe traveling in space and landing on Mars will not be possible without the tens of thousands of high-strength, high-performance fasteners developed and produced by Aerospace Precision Products Co., Ltd. under CASIC, they played an important role in improving the probe's comprehensive performance like high and low temperature resistance, fatigue resistance.
In the future, Mars rover will be unlocked and separated from the landing platform to complete Mars roving mission. The "customized" rectangular separation connector and RF umbilical connector was designed and developed by the GSA, to achieve the physical connection and separation of control signals between the Mars rover and the lander, is a key component to ensure the reliable separation of the three structural components: the back shield, the bottom and the lander.
The surface of Mars is complex, to enable the Mars rover climb up and down the uneven surface freely, Qunjian precision company under AJG designed and developed the "customized" rover suspension deceleration self-locking device. The device consists of two parts, one for the angle adjustment mechanism and the other for the clutch mechanism, which work together to allow the rover to precisely adjust its attitude to the Mars surface terrain. In addition, the accelerometer installed on the Mars rover provides real-time measurement information to the GNC to ensure that the Mars rover can accurately "sense" its real-time speed and position when it is moving, to ensure the safe and smooth work of the Mars rover.
Further reading:
At about 1:00 a.m. on May 15, the Tianwen-1 entered the parking orbit of Mars after performing an orbital maneuver, and fired its engines to allow it to enter orbit around the Mars. At about 4:00, the landing rover separated from the orbiter and entered the Mars atmosphere after about 3 hours of flight, and after about 9 minutes of deceleration, hovering, obstacle avoidance and buffering, successfully soft-landed in the pre-selected landing zone. About 30 minutes after the separation of the rover and lander, the orbiter performed an orbit ascending and returned to its parking orbit to provide relay communications for the lander and rover. Subsequently, the "Zhurong" Mars rover will perform global imaging of the landing site, self-inspection, drive away from the landing platform to perform roving.
China's first Mars exploration mission was formally approved in 2016, and it is planned to achieve Mars orbiting, landing and roving through one mission, orbiting around Mars, and regional roving on the surface of Mars. The Mars probe Tianwen-1 consists of an orbiter and a lander with rover, which includes the "Zhurong" rover and the entry module. Since its successful launch on July 23, 2020, the probe has completed one deep space maneuver and four midway corrections during the Earth-Mars transfer, and on February 10, it successfully entered Mars orbit, becoming the first artificial Mars satellite in China. On February 24, 2021, the Tianwen-1 probe successfully performed the third braking near Mars and entered the Mars parking orbit with a period of 2 Mars days to carry out global remote sensing exploration of Mars and detailed investigation of the pre-selected landing area, detecting and analyzing the terrain and landforms, sand and dust weather, etc., in preparation for landing on Mars. During the mission implementation, CNSA has cooperated with ESA and other international space organizations of Argentina, France, Austria and national space agencies on relevant projects. The probe has now been in space for 295 days and is approximately 320 million kilometers away from the Earth.
This Mars exploration mission features high risk and difficulty, facing challenges such as interplanetary space environment, the thin atmosphere on Mars, the surface landform of the Mars, etc. Also, due to long distance and long time delay, there are difficulties during landing such as environment uncertainty, complex landing procedures, and no intervention measures on the ground. The Tianwen-1 mission tackled the key technologies like second cosmic speed launch, interplanetary flight and TT&C, and soft landing on an superior planet, realizing China's first exoplanet landing, which marks another milestone in the development of China's space industry of great significance.
