"New Elements of Science and Technology" on Tianwen No.1
Yang Qingwu and Yongjiang reporter Wang Lingshuo
At 7:18 on May 15, the Tianwen-1 Landing Patrol successfully landed in the pre-selected landing area in the southern Mars Utopia Plain. my country's first Mars exploration mission to Mars was successfully landed.
Behind the success of Tianwen No.1, it is inseparable from the support of a large number of "new technological elements".
Phased array sensor: the advantages of "clairvoyance" in space
Our country's Mars exploration is aimed at realizing orbiting, landing and patrolling Mars through a single launch.
As an important instrument for position and speed measurement, the phased array sensor continuously provides high-precision measurement data for the spacecraft during the landing phase, and successfully assists the landing patrol to safely land on the surface of Mars.
The phased array sensor is installed under the landing platform of the Mars Landing Patrol Vehicle Entry Module, with a range of tens of kilometers, which can be described as the space "clairvoyance" of the Mars rover.
It closely cooperates with other measurement sensors of different principles, and relays to guide the spacecraft to land safely on Mars.
The spacecraft entered the Martian atmosphere from an altitude of more than 130 kilometers with a speed of 5.9 kilometers per second.
In just a few minutes, returning the spacecraft's speed to zero is the key to the most technically difficult and highest probability of failure of all Mars exploration missions.
According to Sun Wu, chief engineer of phased array sensors, this is the first domestic application of phased array radar for landing measurements on extraterrestrial celestial bodies.
Due to the long distance between Mars and the earth, there is a certain time delay in communication, and the landing process cannot be controlled on the earth. The landing patrol must be allowed to complete this journey autonomously, which places extremely harsh requirements on the sensors.
Sun Wu said: "The radar antenna of a phased array sensor is composed of multiple radiating elements, just like the compound eyes of a dragonfly in biology. It has the characteristics of fast beam scanning, flexible pointing, large target capacity, and strong anti-interference ability."
In addition, the phased array sensor has the measurement function of 9 directions. The spacecraft can switch any 4 directions and measure the distance and speed information at the same time, so as to quickly correct the attitude measurement error of the spacecraft and ensure the accuracy of the landing patrol direction control.
Suspension deceleration self-locking device: small "transmission" has great effect
The surface of Mars has a complex terrain. How can the Zhurong rover accurately transmit motion instructions so that it can walk flexibly and climb downhills?
All this is inseparable from the core transmission component of the Mars Rover mobile subsystem-the suspension deceleration self-locking device.
Without its support, the rover is like a kite with a broken wire.
If the Mars rover is compared to a carriage, then the suspension decelerating self-locking device is the "coachman" who drives this "carriage".
On the left and right suspensions of the rover, two types of suspension deceleration and self-locking devices with precise structure are respectively equipped.
The device is small in size and light in weight. The entire transmission device cooperates with each other to enable the six wheels of the rover to independently raise and lower, realize the attitude and height adjustment of the vehicle body, to adapt to the Martian surface terrain, and ensure free movement when climbing and descending.
The highlight of the Mars exploration mission is to patrol the surface of Mars, and this process must be foolproof.
He Zhibin, the person in charge of the project technology, told reporters that they spent half a year starting from the basic aspects of raw materials, heat treatment, machining, precision testing and testing, and through continuous exploration and innovation, they have overcome many difficulties along the way and ensured Mars. The car is more autonomous and flexible in turning and crossing slopes.
Nano aerogel: "Ultra-thin jacket" stands out
To ensure that the Tianwen-1 rover successfully landed on Mars and worked normally, the rover used a new type of thermal insulation material-nano aerogel.
Not only can it be used to cope with the harsh environment of extreme heat and extreme cold, but with its ultra-light characteristics, it can greatly reduce the burden on the rover, allowing it to run faster and farther.
Nano-aerogel is a three-dimensional network composed of nano-scale solid frameworks. The density can be made lower than that of air. It is the lightest solid in the world. The thermal conductivity is only half of that of still air, and it is the solid with the lowest thermal conductivity.
This makes it the best choice for Tianwen-1 to deal with harsh environments such as extreme cold and extreme heat.
During the Mars landing phase, the heat generated by the landing engine will cause the surrounding temperature to exceed 1000°C. This extreme heat test exceeds the temperature resistance limit of the world’s aerogel materials; while the extreme cold test occurs in the Mars patrol phase, it is necessary to ensure that the rover It works normally at -130℃.
Even more difficult is that in order to reduce the burden on the rover, aerogels are required to have an ultra-low density, which poses a huge challenge to the design and preparation of materials.
It is reported that the aerogel material used in the Tianwen-1 detector has passed nearly a hundred tests such as physical properties, mechanical properties, thermal insulation properties, and space environment weather resistance.