China News Service, Beijing, May 15th, title: The key to slow down!

How does this "parachute" protect the sky and land on Mars?

  Author Guo Chaokai Li Li

  The "Tianwen-1" Landing Patrol successfully landed on the pre-selected landing zone in the southern Utopia Plain of Mars on the 15th.

During its landing, China’s newly developed "Tianwen No. 1" parachute deceleration subsystem fulfilled its mission and played a key role in decelerating the "Tianwen No. 1" successful landing.

The rendering of Tianwen 1 landing on Mars.

Photo courtesy of the Eighth Academy of China Aerospace Science and Technology Corporation

Adopt the parachute deceleration commonly used internationally

  The "Tianwen-1" landing patrol adopts the parachute deceleration method commonly used internationally to further decelerate for a safe landing on Mars. However, in the design, verification, simulation analysis and test verification of the Mars parachute system, there are also other countries. Many differences.

  The "Tianwen No. 1" parachute deceleration sub-system was developed by the 508 Institute of the Fifth Academy of China Aerospace Science and Technology Corporation. For the first time, its parachute adopts a zigzag coiled parachute, which is matched with the largest spacecraft pyrotechnic device cartridge in China. The parachute rope insertion technology deepens the parachute inflation process and the dynamics simulation of the parachute system. Based on the conditions in China, the parachute high-altitude opening test and the helicopter launch strength test have been fully carried out.

  "Tianwen No.1 uses a main parachute, one-time inflation and deceleration plan. The parachute is a zigzag-shaped coiled umbrella with a disk, followed by a circle of seams, and a belt underneath. The tail of the belt is made of zigzag. The shape is conducive to load-bearing and stability.” Experts from 508 said that after the “Tianwen No. 1” landing patrol entered the Martian atmosphere, it decelerated under its own aerodynamic shape. After the parachute was opened, it decelerated further to approximately approximately one second per second. After 95 meters, the landing patrol enters the hovering obstacle avoidance section.

Parachute test verification is unprecedentedly difficult

  The opening conditions of the Martian parachute are quite special, which are mainly reflected in the opening of the parachute at supersonic speed, low density, and low dynamic pressure.

In view of the special opening conditions of the Martian parachute, 508 scientific researchers have taken corresponding special measures in the design and development of the parachute in terms of umbrella type selection, design parameter selection, material selection, and local structure improvement.

  The scientific research personnel fully draw on the experience of the same umbrella type of the previous sounding rockets and the achievements of foreign Mars exploration parachutes, optimize the design parameters of the coiled parachute, use some newly developed special textile materials for the first time, and connect the parachute rope for the first time. Using the plug-in process, the connection strength is significantly improved compared to the sewing process.

  The special parachute opening conditions of Mars make the test and verification of the parachute unprecedentedly difficult.

On the earth, the test simulation method closest to the real parachute opening conditions of Mars is the high-altitude parachute opening test, which creates a supersonic parachute opening condition at a height of about 40 kilometers on the surface of the earth, which can verify the functional performance of the Martian parachute to the greatest extent. .

  How to send the parachute to an altitude of 40 kilometers?

Whether using high-altitude balloons or sounding rockets, it is a high-cost and high-risk test verification method.

What is gratifying is that after 6 years of development and experimentation, 508 researchers have overcome many difficulties such as the difficulty of parachute opening conditions and abnormal parachute opening, and handed in a "perfect answer sheet" for the "Tianwen No. 1" landing on Mars. .

(Finish)