China’s reusable rocket recovery net system

On July 10, the Long March 10B rocket took off from the Wenchang Satellite Launch Center, Hainan Island, on its first test flight. About six minutes after separation from the second stage, the first rocket stage made a controlled vertical descent. This part was then picked up by Navigator, a vehicle equipped with a specialized net rig, at sea, more than 300 km from the launch site.

“Very true to the center of the grid. The precise control ability is excellent,” commented Chen Mingbo, Chairman of China Aerospace Science and Technology Corporation (CASC).

The event marked the first time China successfully recovered a rocket booster during a flight to orbit, becoming the second country after the United States to do so. According to Global Timesthis is also the first time in the world that a rocket stage has been recovered using a net system.

The Long March 10B is a liquid-fueled two-stage rocket supervised by the China Institute of Launch Vehicle Technology (CALT) under CASC. This reusable rocket is 70 m high, 5 m wide, has a launch mass of about 760 tons and can carry 16 tons of cargo into low Earth orbit.

While reusable rockets often land with deployable landing legs, such as SpaceX’s Falcon 9, the Truong Chinh 10B uses four hooks located next to the mesh fins in the body. During landing, they will hook onto the Navigator’s steel cables.

Navigator is China’s first specialized net missile capture vehicle, 144 m long, 50 m wide and weighs 25,000 tons when fully equipped. Thanks to the dynamic positioning system, this vehicle can maintain its position in turbulent conditions, acting as a reliable mobile landing platform on vast seas.

According to Sun Zhenlian, a technical expert at CALT, when the first stage of the Long March 10B rocket reached the space above the recovery platform, it continued to decelerate. The missile stage’s positioning and guidance system continuously collects real-time velocity and position data, transmitting information to the control system to adjust direction and speed accordingly. At the same time, Navigator also monitors the status of the missile stage to control the capture cable.

Sun calls this process a “two-way meeting” with high precision. The entire process takes place in a short time, is affected by wind and waves at sea, and requires close coordination between the rocket body, cables and hook mechanism. “This is like dropping a pen from the 100th floor into the pen holder while still controlling the speed and direction,” Hao Jinjie, an engineer working at CASC, told CGTN.

The instantaneous load also poses a huge challenge to the hook mechanism, requiring it to withstand the complex forces of contact with the net, slipping or pulling. “The hook mechanism is like a powerful hand, holding the rocket stage tightly,” Sun described.

Next, the Navigator must secure the rocket stage. “Due to environmental factors such as waves and sea breezes, the rocket stage can wobble inside the trellis. The recovery system stabilizes it in two steps. First, auxiliary cables hold the rocket stage tightly in multiple directions. Then, the locking platform automatically moves underneath, clamps and locks,” Sun explained. The process is like tightening a seatbelt around a rocket stage, making it stable even at sea, he added.

According to Chen Muye, technical expert at CALT, the net recovery system has many advantages, including simplifying the rocket structure because it does not need to be equipped with landing legs. This further reduces overall mass, increasing cargo capacity and performance for the missile. The net can also be adjusted flexibly, so the ability to tolerate deviations when landing is quite good. In addition, the system can be designed in modular form to serve many different sized missiles.

Experts will refurbish the recovered thruster stage to reuse it for the next flight, expected to take place later this year. “If the number of reuses is high enough, costs can be reduced by 20-30%. With further improvements, the reduction can reach 50-60%,” Hao commented..

Kan Lei, a rocket technology expert at CALT, said that the success of the Long March 10B launch and recovery mission marked an important step forward in China’s space industry. In the future, reusable technology is expected to significantly reduce commercial launch costs, while improving China’s competitiveness in the world market.