ISRO has successfully carried out a rare and complex space maneuver, orchestrating a precise formation flight between two satellites. These satellites, moving at an astonishing speed of 28,800 km/h—nearly ten times faster than a bullet—are part of the Space Docking Experiment (SpaDeX), which began in December. Every 90 minutes, at an altitude of about 500 km, they engage in this high-speed orbital dance.
As a major milestone in this mission, India achieved its first-ever satellite docking on January 16. One satellite, called the ‘chaser,’ successfully linked with the other, known as the ‘target.’ Then, after carefully waiting for the Sun to be in the correct position, ISRO successfully undocked, or de-docked, them on March 13.
With this accomplishment, India became only the fourth nation—after the United States, Russia, and China—to master this advanced space technology. Notably, India achieved this feat on the very first attempt and used its own indigenous docking system, the Bharatiya Docking System. Even more impressive is that the mission was completed at a cost of under ₹300 crore, reinforcing ISRO’s reputation for delivering high-value space missions at minimal costs.
However, one key experiment in the mission—transferring electrical power between the two satellites—was not completed in the initial docking phase. ISRO Chairman Dr. V Narayanan explained that “In the first attempt there was a suspicion of a minor misalignment of the power transfer ports (and) hence this was postponed to the next round.”
Despite this setback, ISRO remains optimistic. The remaining objectives of the mission, including the power transfer experiment, are expected to be carried out in May, as there is still sufficient fuel left on the SpaDeX satellites.
The primary goal of SpaDeX is to develop and demonstrate crucial technologies related to spacecraft rendezvous and docking. It also aims to test how well the docked satellites function together, which could eventually help extend the lifespan of satellites in space. Additionally, once docking is complete, the mission allows for independent payload operations.
Following the successful docking, Prime Minister Narendra Modi acknowledged the achievement, stating, “Congratulations to our scientists at ISRO and the entire space fraternity for the successful demonstration of space docking of satellites. It is a significant stepping stone for India’s ambitious space missions in the years to come.”
Science Minister Dr. Jitendra Singh also expressed his excitement, saying, “Congrats ISRO. Finally made it. SpaDeX has accomplished the unbelievable… docking complete… and it is all indigenous.”
This breakthrough lays the foundation for India’s future space ambitions, including the Bharatiya Antariksha Station (India’s planned modular space station), Chandrayaan 4 (a lunar sample return mission set for 2027), and Gaganyaan (India’s first crewed space mission).
