It is the first time China has landed a probe on a planet other than Earth.
Tianwen 1, consisting of an orbiter, a lander and a rover, was launched from the Wenchang Spacecraft Launch Site on the coast of southern China's island province of Hainan on July 23, 2020. It was the first step in China's planetary exploration of the solar system, with the aim of completing orbiting, landing and roving on the red planet in one mission.
The name Tianwen, meaning Questions to Heaven, comes from a poem written by the ancient Chinese poet Qu Yuan (about 340-278 BC). China's first Mars rover is named Zhurong after the god of fire in ancient Chinese mythology, which echoes with the Chinese name of the red planet: Huoxing (the planet of fire).
The spacecraft entered the Mars orbit in February after a journey of nearly seven months through space, and spent more than two months surveying potential landing sites.
In the early hours of Saturday, the spacecraft began to descend from its parking orbit, and the entry capsule enclosing the lander and rover separated from the orbiter at about 4 am.
After flying for approximately three hours, the entry capsule hurtled toward the red planet and entered the Mars atmosphere at an altitude of 125 km, initiating the riskiest phase of the whole mission.
First, the specially designed aerodynamic shape of the entry capsule decelerated with the friction of the Martian atmosphere. When the velocity of the spacecraft was lowered from 4.8 km per second to about 460 meters per second, a huge parachute covering an area of about 200 square meters was unfurled to continue reducing the velocity to less than 100 meters per second.
The parachute and the outer shield of the spacecraft were then jettisoned, exposing the lander and rover, and the retrorocket on the lander was fired to further slow the speed of the craft to almost zero.
At about 100 meters above the Martian surface, the craft hovered to identify obstacles and measured the slopes of the surface. Avoiding the obstacles, it selected a relatively flat area and descended slowly, touching down safely with its four buffer legs.
The craft's plummet through the Martian atmosphere, lasting about nine minutes, was extremely complicated with no ground control, and had to be performed by the spacecraft autonomously, said Geng Yan, an official at the Lunar Exploration and Space Program Center of the CNSA.
"Each step had only one chance, and the actions were closely linked. If there had been any flaw, the landing would have failed," said Geng.
Published : May 15, 2021
By : China Daily/ANN