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Braking is a key and risky step in the Mars exploration mission, which requires a high degree of precision. Only when braking is done with a precise time and duration, can the probe successfully enter the orbit of the planet.
BEIJING, February 11 – Precise braking near Mars helped China’s Tianwen-1 probe successfully enter orbit around the red planet on Wednesday, according to the country’s space scientists.
Yang Yuguang, a researcher at China Aerospace Science and Industry Corporation Limited, told Science and Technology Daily that braking is a key and risky step in the Mars exploration mission, which requires a high degree of precision.
When a probe is set up to be captured by a planet’s gravity, the lower its orbit, the more fuel the engine will save. But if Tianwen-1 slows in an orbit too close to Mars, the probe may collide with the planet’s surface, since there may be minor errors in its measurement and position control, Yang said.
If the braking time is too long, resulting in excessive braking force, the probe will also face the risk of crashing, he said.
“Only when braking is done with a precise time and duration can the probe successfully enter the orbit of the planet,” said Pang Zhihao, an expert in deep space exploration technologies.
The Tianwen-1 slowdown began with a 3000N engine running at 7:52 pm (Beijing time) on Wednesday. After about 15 minutes, the spacecraft, including an orbiter, lander, and rover, had slowed enough to be captured by the gravity of Mars and entered an elliptical orbit around the red planet, with its distance. closest to the Martian surface about 400 km. , according to the China National Space Administration.
Braking near Mars is different from braking near the moon, which China’s lunar probes have successfully accomplished on previous lunar missions.
The average distance between the Earth and the Moon is about 384,400 km, and the communication delay is only one second. But the distance between Earth and Mars is more than 180 million km and the delay of one-way communication is more than 10 minutes.
“In this case, the earth cannot monitor the spacecraft in real time. The instructions must be transmitted in advance and executed independently by the spacecraft,” explained Yang.
But slight deviations in engine thrust and different variables related to the spacecraft’s position, speed and attitude will add to the complexity of achieving autonomous control, he said, adding that to ensure smooth autonomous control. , Tianwen-1 is equipped with multiple sensors to allow for accurate measurement of flight conditions.
Weighing in at more than 5 tons, Tianwen-1 is among the heaviest planetary probes in the world. But scientists and engineers have managed to equip it with a relatively small engine to leave more weight and space for payloads. To compensate for the small push, they extended the braking time to meet braking requirements, Yang said.
