How Can a Spacehand Assemble Giant Satellites?

In 2023 the Shenzhou‑15 crew used a brand‑new tool for the first time: a handheld dual‑point docking mechanism. It is meant to connect very large payloads—bigger than the launch vehicle—during extravehicular activities (EVA). The device features two probe‑and‑drogue elements that snap together, ensuring precise alignment even when astronauts are not perfectly aligned. A force‑amplification system turns a small hand effort into a rigid connection, allowing locking or unlocking with a single motion. Its ergonomic design lets users switch hands, operate with one hand, and apply limited force—crucial in micro‑gravity. Before flight, engineers simulated dynamics, statics and kinematics with computational models and tested the prototype at extreme temperatures, from –150 °C to +150 °C, to verify durability and accuracy. The results matched finite‑element predictions. This tool paves the way for more ambitious space constructions, such as larger stations or ultra‑long‑focus telescopes, reducing reliance on autonomous robots and boosting mission flexibility.

The dual‑point mechanism was designed using Human Factors Engineering principles. The probe‑and‑drogue configuration allows a misalignment tolerance of ±5 mm in translation and ±2° in rotation, thanks to flexible guides and a spring‑loaded latch. The force‑amplification system employs a four‑arm lever with a 1:12 transmission ratio, so a 10 N hand force yields roughly 120 N of compression at the contact point, ensuring a rigid lock without excessive effort. Numerical simulations were performed with finite‑element software (ANSYS) to assess static and dynamic stresses during approach, capture, and release phases. Results showed stress peaks below 30 % of the fatigue limit of the material (Aluminum 7075‑T6). Thermal tests simulated the ISS environment, cycling between –150 °C and +150 °C, confirming dimensional tolerances stayed within ±0.2 mm. Kinematic tests identified an optimal approach speed of 0.02 m/s, minimizing impact risk. Validation included vacuum chamber docking trials with integrated force sensors for real‑time load monitoring. These analyses provide a robust foundation for future missions, where modularity and the ability to assemble large structures will be essential for lunar habitats or expanded orbital stations.