The Indian Space Research Organisation’s (ISRO) Space Docking Experiment (SpaDeX) mission has now entered a critical phase. The mission aims to demonstrate spacecraft docking for the first time in India’s space history, a feat that, if successful, would position India alongside the United States, Russia, and China in mastering this advanced technology. The SpaDeX mission, launched on December 30, 2024, involves two small satellites, SDX01 (Chaser) and SDX02 (Target). These satellites are tasked with rendezvousing and docking in orbit—a complex and delicate process requiring precise alignment and connection. This capability is essential for constructing modular space stations, conducting interplanetary missions, and enabling satellite servicing.
Despite its ambitious goals, the mission has encountered significant hurdles. A couple of days ago, ISRO aborted its third docking attempt. The latest attempt, which began just after midnight, saw the satellites approach each other, narrowing the distance from 230 meters to 15 meters using a slow drift technique. At this stage, both satellites were poised for docking, and optimism ran high. However, complications arose when the team tried to reduce the distance further to three meters. A critical issue emerged with the proximity and docking sensor—a key component that ensures precise alignment of the satellites. Although the drift was stabilised at zero degrees, a delay in receiving sensor signals forced the onboard systems to trigger a safe mode. This precautionary measure moved the satellites to a safe distance to avoid potential collisions. The satellites have since separated by over eight kilometres.
ISRO is now conducting a detailed analysis to address the sensor issue before attempting another docking. This apparent setback indicates the inherent complexity of space docking—a process fraught with technical challenges. Officials within ISRO are learnt to have acknowledged the difficulties but expressed optimism about future attempts. However, persistent sensor issues and poor visibility conditions could delay the next attempt. The SpaDeX mission represents a pivotal step in India’s space ambitions. Docking technology is essential for future projects like the Bharatiya Antriksh Station, slated to launch its first module in 2028, and the Chandrayaan-4 mission, which aims to return lunar samples. Beyond national aspirations, mastering docking capabilities could open doors for India to collaborate on international space initiatives. This would reinforce the nation’s reputation as a key player in global space exploration.
The hurdles faced during the SpaDeX mission highlight ISRO’s resilience and its methodical approach to problem-solving. Each aborted attempt provided valuable data and insights, bringing the agency closer to success. This iterative process is emblematic of ISRO’s broader journey—a journey that has been marked by determination, innovation, and a firm commitment to push the boundaries of what is possible in the space domain. As ISRO continues to refine its methods and troubleshoot technical challenges, the SpaDeX mission will, in most likelihood, assert India’s growing expertise in space technology. It is not merely about two satellites docking in orbit; it is about laying the groundwork for a future where India plays a leading role in space exploration and collaboration. The success of this mission, whenever it comes, will mark a new chapter in India’s space story, filled with opportunities and global significance. The learning curve for ISRO is on an upward trajectory. In this sense, there is no success or failure, only progress.