SpaceX’s "Chopstick Rocket": A New Breakthrough in Aerospace
1.SpaceX's Starship Test Flight Makes History
In less than two years, SpaceX's Starship has already completed five successful test flights, each pushing the boundaries further. This latest fifth flight was a major milestone: for the first time, a robotic arm "chopstick grasped" the rocket booster, successfully recovering it. This groundbreaking feat has sent shockwaves around the world. Standing at a towering 120 meters tall with a diameter of 9 meters, Starship is currently the largest and most powerful launch vehicle ever built.
2.The Meaning of "Chopsticks Holding a Rocket"
2.1 Weight Reduction & Fuel Increase
SpaceX's reusable Falcon 9 rocket uses four metal landing legs on its boosters, which add unnecessary weight during launch. The Starship, however, utilizes a "chopstick grip" method for recovery, eliminating this extra weight and freeing up space for more fuel. This approach significantly increases fuel reserves, providing the necessary power for longer-range space exploration missions.
2.2 Shorten Development Cycles
"Starship" landed directly on the launch tower this time, requiring only maintenance and a refueling to be ready for liftoff. Landing on remote ground would necessitate transporting it back to the factory and then the launch tower, a process that would take significantly longer.
Musk emphasized that "Starship" is designed to achieve a full booster re-launch within an hour of landing. This includes a 5-minute return for the booster, with the remaining time dedicated to refueling and readying the spacecraft. This approach drastically shortens the development cycle and accelerates the rate of subsequent launches.
2.3 Toward Reusable Keys
The "chopstick rocket" is a major step towards reusable rockets. This method not only lightens the rocket's weight but also shortens the development cycle, significantly reducing costs. NASA Administrator Bill Nelson praised this innovation, believing it will prepare humanity for missions to the Moon and beyond to Mars. In the future, Starship's second-stage spacecraft will serve as a human transport to the Moon, ferrying astronauts from lunar orbit to the surface.
3. Technological Challenges and Breakthroughs
3.1 High-precision Dynamic Control
During the return process, both the rocket booster and the robotic arm are in motion, making it incredibly challenging to achieve precise, synchronized coordination between them.
The rocket booster, traveling at high speeds with a complex trajectory during its return, requires a sophisticated navigation and control system to ensure it returns to the launch tower as planned. Simultaneously, the robotic arm must continuously adjust its position and orientation to accurately grasp the booster. This demands highly precise communication and coordination between the two; even slight errors could lead to failure.
However, SpaceX engineers have successfully achieved this high-precision dynamic control through advanced sensor technology and complex algorithms. They equipped both the rocket booster and the robotic arm with numerous sensors that constantly monitor parameters such as their location, speed, and orientation. A high-speed data transmission and processing system then rapidly adjusts the robotic arm's movements to keep it synchronized with the rocket booster. For example, during Starship's fifth test flight, the robotic arm began pre-adjusting based on real-time sensor data even before the booster was close to the launch tower, ensuring a precise grasp upon its arrival.
3.2 Powerful Powertrain
Gripping a rocket booster with the robotic arm requires immense torque. This is due to the booster's weight of 200 tons during its return, compounded by the impact force generated from high-speed motion, placing incredibly high demands on the robotic arm's power system. To meet this need, SpaceX developed a robust power system. They started by utilizing high-performance motors and hydraulic systems capable of generating enough power to securely hold the booster. Furthermore, they optimized the mechanical arm's structural design to enhance its torque resistance capabilities. For example, the arm's joints are constructed from high-strength alloys designed to withstand immense pressure and torsion. SpaceX also rigorously tested and fine-tuned the power system to ensure stable operation under diverse conditions. During Starship's fifth test flight, the robotic arm successfully gripped the booster, demonstrating the reliability and effectiveness of its powerful system.
3.3 Stable Descent
A stable landing for the booster, free of major jolts, is absolutely critical. A rough touchdown could prevent the robotic arm from accurately grasping the booster and cause serious damage to both the launch tower and the rocket itself.
SpaceX has implemented several measures to ensure a smooth landing. First, advanced attitude control systems are fitted to the rocket boosters, allowing them to continuously adjust their position and maintain stability during descent. Second, precise navigation and control technology guides the booster to land accurately within a designated area near the launch tower. Additionally, the robotic arm incorporates some cushioning capabilities to absorb a portion of the impact force when seizing the booster, minimizing any vibrations.
During Starship's fifth test flight, the booster demonstrated excellent stability during landing, setting the stage for a successful capture by the robotic arm.
