Xi'an Science and Technology escorted the entire process of "wandering, falling and returning" for "five sisters"

　　BEIJING, November 24 Xi'an electric

　　China News Service reporter Tian Jin

　　On the 24th, the "Five Sisters" of the Chang'e family of China's lunar exploration project, the Chang'e-5 probe officially set off.

The Xi’an Branch of the Fifth Academy of China Aerospace Science and Technology Corporation (“Xi’an Branch” for short) has developed a microwave ranging and speed measurement sensor, a measurement and control antenna, a data transmission subsystem, and a rendezvous and docking microwave radar for the Chang'e-5 detector. "Fall and return" to escort the whole journey.

The Chang'e-5 detector development team of Xi'an Branch.

Photo courtesy of Xi'an Branch

　　At a distance of 380,000 kilometers away from the earth, how to make the Chang'e-5 probe "Five Sisters" establish a smooth connection with the ground depends on the measurement and control antenna developed by the Xi'an Branch.

Almost all working modes of the "Five Sisters" during the earth-moon transfer, the orbit change and the lunar circumnavigation phase, the power drop, the lunar surface working phase of the ascender, and the rendezvous and docking phase require the use of measurement and control antennas for measurement and control communication with the earth.

The measurement and control antenna is equivalent to the "mobile phone" carried by the "five sisters", and the measurement and control communication with the moon is mainly completed by this "mobile phone".

　　The "mobile phone" equipped by the Xi'an branch for the "five sisters" must not only consider the range of hearing, but also ensure that it is not interfered by other surrounding devices.

Therefore, the designer has fully considered the layout of the measurement and control antenna on the riser to ensure that it works effectively, and requires that the antenna is not blocked within the range of 180 degrees of rotation.

At the same time, the designers also carried out the integrated design of antenna machine, electricity and heat according to factors such as the influence of the plume during the setting of the moon, ensuring that the measurement and control antenna can reliably operate under the extremely harsh environment of the setting moon, moon dust and lunar surface. jobs.

　　After the Chang'e-5 probe reaches the lunar orbit, the lander will land on the lunar surface with the ascender.

Whether it can safely land on the surface of the moon is a key step in the mission of the Chang'e-5 probe.

The microwave ranging and speed sensor developed by Xi'an Branch for Chang'e-5 is equivalent to installing a "parking radar" on the lander.

The developers of the Chang'e-5 detector of the Xi'an Branch are conducting testing and verification.

Photo courtesy of Xi'an Branch

　　"This radar officially began to work when the lander was 15 kilometers away from the surface of the moon. The main task was to measure the distance between the lander and the surface of the moon and the speed of the lander's descent, and quickly move towards the ascender's guidance, navigation and control sub-system ( GNC subsystem) provides speed and distance information so that the lander can judge the landing point and speed of the landing." said Zhang Aijun, the chief designer of the microwave range and speed sensor of the Xi'an Branch.

The microwave distance measurement speed sensor will greatly facilitate the "five sisters" to control their posture and "park" smoothly.

　　Taking pictures is essential for moon exploration.

How the photos taken by the camera carried by the "five sisters" can be transmitted back to the ground in a timely manner requires the digital transmission subsystem developed by the Xi'an branch for the Chang'e-5 detector.

When the lander is ready to land on the surface of the moon, the digital transmission subsystem starts to work.

It will transmit the landing pictures and data information taken by the camera installed on the lander back to the ground in real time, so that the ground can make timely judgments on the information of the falling moon.

After the lander successfully landed on the lunar surface, the digital transmission subsystem installed on the lander will transmit the sampled images of the lunar working section, the scientific data obtained by sampling and drilling, and the image data of the ascender’s take-off process to the ground for the mission The smooth progress of the project provides a reference for decision-making.

　　"In order to improve the efficiency of data transmission, the Xi'an Branch has designed an adaptive three-speed adjustment method, which is equivalent to installing a three-speed'gate' for data transmission. During peak transmission periods, a transmission method with a smaller amount of data is used. The system can transmit data from 500k to 5M. According to the maximum transmission rate, it only takes one second to transmit a 5M photo." said Zhang Jing, the designer of the digital transmission subsystem.

　　The digital transmission subsystem equipped for "Five Sisters" is equivalent in function to Chang'e-4, but the "Five Sisters" have been greatly "slimted" in terms of weight and volume through integration and miniaturization.

The weight of the Chang'e 4 digital transmission system is 8 kg, while the Chang'e 5 digital transmission system is only 3.5 kg.

　　How to successfully deliver the lunar surface samples collected by the ascender to the returner and smoothly bring it back to earth must be completed through the complex "divine operation" of rendezvous and docking.

The rendezvous and docking microwave radar developed by the Xi'an Branch is designed for the "penetrating" rendezvous and docking at a distance of 380,000 kilometers from the earth.

The rendezvous and docking microwave radar is equivalent to aiming at the "eye of a needle" for the "pinning" of space.

　　When the ascender returns to the lunar orbit with the lunar soil samples, the orbiter tracks the ascender.

When tracking to within 100 kilometers, the rendezvous and docking microwave radar began to work.

The rendezvous and docking microwave radar developed by the Xi'an Branch can measure the relative distance, azimuth, pitch angle and changes between two aircraft.

These data and information will be continuously sent to the central processor of the orbiter's guidance, navigation and control subsystem (GNC subsystem) to provide real-time information for the rendezvous and docking of the two devices.

In addition to aiming at the “eye of the needle” for space through distance measurement, speed measurement and angle measurement, the rendezvous and docking microwave radar can also realize the communication between the two devices.

From the establishment of a communication link between the two devices 100 kilometers apart to within 0.2 meters between the two devices, two-way communication between the orbiter and the ascender can be realized, and some information including instructions must be communicated through the two-way communication between the devices. achieve.

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