The Indian Space Research Organisation (ISRO) has postponed its Space Docking Experiment (SpaDeX) for a second time, citing an unexpected drift between the mission satellites.
The experiment, originally slated for Tuesday, was rescheduled for Thursday but remains delayed with no new date announced.
The Bengaluru-headquartered space agency shared the development on X, stating, “While making a manoeuvre to reach 225 m between satellites, the drift was found to be more than expected, post non-visibility period. The planned docking for tomorrow is postponed. Satellites are safe. Stay tuned for updates.”
Earlier, ISRO deferred the mission, explaining the need for further validation via ground simulations. “The process requires further validation through ground simulations based on an abort scenario identified today,” the agency had noted.
Also read: ISRO gears up for historic SpaDeX docking
The SpaDeX mission is a significant step for India’s space programme. It aims to develop and demonstrate the sophisticated technologies required for spacecraft rendezvous, docking, and undocking using two small satellites. ISRO describes the project as a milestone in advancing India’s capabilities in satellite servicing, space station operations, and interplanetary missions.
On 30 December, ISRO’s Polar Satellite Launch Vehicle (PSLV) successfully deployed twin 220-kg satellites into a 470-km circular orbit. The mission involves a chaser and target satellite separated by 20 km, travelling at 28,800 km/h. Despite their high velocity, the satellites appear stationary due to their zero relative velocity.
When the docking operation begins, the satellites will be manoeuvred closer in phases, reducing inter-satellite distances progressively to 5 km, 1.5 km, 500 m, 225 m, 15 m, and 3 m before the final docking. During this critical phase, the chaser will approach the target at a speed of 10 nm per second to achieve a precise connection.
Commenting on the complexity of the mission, ISRO Chief S Somanath remarked, “They will do the docking exercise only when all sensors have been fully calibrated and tested to satisfaction before it is attempted. All algorithms and scenarios are also tested on the ground before commands are sent to the spacecraft to autonomously do the docking.”
The mission will be deemed successful when electrical power is transferred from one satellite to the other after docking, allowing the pair to operate as a unified spacecraft. Upon completion of the docking and undocking processes, the satellites will resume independent operations.
Docking technology, mastered by China, the United States, and Russia, is vital for future missions involving space stations and interplanetary exploration.
The SpaDeX mission marks a critical step in India’s quest to join this elite group of nations.
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