ISRO Achieves Key Milestone with Second Autonomous SPADEX Satellite Docking
India’s space agency, ISRO, has successfully completed its second docking of the SPADEX satellites—SDX 01 and SDX 02—on 20 April 2025 at 8:20 PM. This achievement marks another step forward in the advancement of autonomous space technologies.
Fully Autonomous Docking from 15 Metres
This second docking was executed entirely through autonomous systems. The satellites connected from an inter-satellite distance of 15 metres without any manual intervention. In comparison, the first docking attempt involved a manual hold point at a 3-metre distance before completion. This shift to full autonomy reflects ISRO’s progress in satellite docking technology.
Power Transfer Conducted Between Satellites
Following the docking, ISRO also tested inter-satellite power transfer on 21 April 2025. The satellites successfully exchanged power, with each unit supplying energy to the other. During the test, a heater element on one satellite was operated using the other satellite’s power. This transfer lasted about four minutes and met all performance expectations.
Lessons from First Attempt Boost Second SPADEX Docking Success
ISRO’s team prepared for this demonstration by analysing data from the first docking and undocking efforts. They carried out extensive ground simulations and in-orbit trials, building on lessons learned. These preparations proved crucial in executing the fully autonomous second docking.
The success of this mission marks a major milestone for the SPADEX programme. It demonstrates ISRO’s capabilities in satellite autonomy and cross-satellite power management—key technologies for future space missions.
