Long March 3B rocket achieves new milestone

The successful launch of the Tianwen 2 robotic probe on Thursday morning marked the latest achievement of the Long March 3B rocket model.

The rocket, developed by the China Academy of Launch Vehicle Technology in Beijing, is primarily used to launch satellites into geostationary transfer orbits, and it can transport 5.55 metric tons of payloads to such orbits. It can also send spacecraft to other types of orbits, such as the medium-Earth and lunar transfer orbits.

The Long March 3B is 56.3 meters tall and has a diameter of 3.35 meters, and it runs on liquid propellants. The rocket has three stages and four side boosters, each 2.25 meters wide, and weighs 456 metric tons when filled with fuel.

It is the most used rocket model in China, having made 109 flights as of Thursday. It has completed several national programs, including ferrying most of the Beidou navigation and positioning satellites to their orbits and placing the Chang'e 3 and Chang'e 4 lunar probes on their moon-bound trajectories.

The Tianwen 2 mission marks the Long March 3B's maiden flight aimed at thrusting a spacecraft out of Earth's orbit, which means that when the rocket separated from the probe, it surpassed the escape velocity of 11.2 kilometers per second required to get away from Earth's gravitational pull. This achievement once again testifies to the model's structural strength and reliability, according to its designers.

The ultrafast speed, together with the fact that the asteroid is very far and small, required an extremely high level of aiming accuracy. A minor deviation could have led to overshooting by millions of kilometers, said Zhang Yipu, a senior designer of the rocket.

"Metaphorically speaking, it was like pitching a basketball from Shanghai and guaranteeing that it would hit a designated rim in Beijing at a predetermined speed and angle," Zhang said, adding that they used new technologies to improve the rocket's guidance and speed adjustment systems to ensure this demanding launch mission was successful.