The brake is an important and risky step in the Mars reconnaissance, which requires a high degree of accuracy. Only when the brake is applied with a precise timing and duration can the probe successfully enter the orbit of the planet.
BEIJING, 11 February. Precise brakes near Mars helped China’s probe Tianwen-1 successfully enter orbit the red planet Wednesday, according to the country’s space scientists.
Yang Yuguang, a researcher at China Aerospace Science and Industry Corporation Limited, told the Science and Technology Daily that the brake is an important and risky step in the Mars investigation, which requires a high degree of accuracy.
When a probe is detected by the gravity of a planet, the lower its orbit, the more fuel the engine will save. But if Tianwen-1 brakes in an orbit too close to Mars, the probe could collide with the planet’s surface, as there could be small errors in position measurement and control, Yang said.
If the braking time is too long, resulting in excessive braking force, the probe will also run the risk of crashing, he said.
“Only when the brake is performed with a precise timing and duration can the probe successfully enter the orbit of the planet,” said Pang Zhihao, an expert in depth exploration technologies.
The delay of Tianwen-1 started with a 3000N engine on Wednesday at 19:52 (Beijing time). After about 15 minutes, the spacecraft, including an orbit, a lander and a rover, slowed down enough to be captured by Mars’ gravity and entered an elliptical orbit around the red planet, with its nearest distance of the Martian surface at about 400 km, according to the China National Space Administration.
Braking near Mars is different from braking near the moon, which has successfully reached China’s lunar probes in previous lunar missions.
The average distance between the earth and the moon is about 384,400 km, and the communication delay is only about one second. But the distance between Earth and Mars is more than 180 million km, and the one-way communication delay is more than 10 minutes.
“In this case, the ground cannot monitor the spacecraft in real time. Instructions must be sent in advance and executed independently by the spacecraft,” Yang explained.
But minor deviations in engine power and various variables regarding the position, speed and attitude of the spacecraft will all contribute to the complexity of achieving autonomous control, he said. for the accurate measurement of flight conditions.
Weighing more than 5 tons, Tianwen-1 is one of the world’s heaviest planetary sins. But scientists and engineers have managed to equip it with a relatively small engine to allow more weight and space for payloads. To make up for the small thrust, they extended the braking time to meet the braking requirements, Yang said.