April 21, 2025
ISRO successfully demonstrated the docking of the SPADEX satellites (SDX 01 & SDX 02) for the second time on April 20, 2025 at 08:20 PM.Subsequently, power transfer from SDX 02 to SDX 01 satellite as well as vice versa was also exercised and accomplished on 21st April, 2025. The experiment involved operating a heater element in one of the satellites through power from the other satellite.The duration of power transfer was approximately 4 minutes and the performance of the satellites was as expected.
In the second docking attempt, the docking was completed with full autonomy from an inter-satellite distance of 15m till docking, whereas in the first docking attempt, an additional hold point was manually exercised at an inter-satellite distance of 3m.
The second docking experiment was preceded by detailed ground simulations and on-orbit trials incorporating the experience gained from first docking & undocking experiments, thereby providing immense confidence for the second docking demonstration.
The demonstration of the fully autonomous second docking along with power transfer marks the completion of an important milestone in the SPADEX mission.