The Indian Space Research Organisation (ISRO) is set to achieve a significant milestone with its ‘SpaDeX’ (Space Docking Experiment) mission, scheduled for December 30. This ambitious mission will attempt to dock two satellites in space, a feat previously mastered only by Russia, the United States, and China. The process, requiring the alignment of two orbiting space assets traveling at a staggering velocity of 28,800 kilometers per hour, is a critical step in advancing India’s space exploration capabilities.
The SpaDeX mission will utilize the Polar Satellite Launch Vehicle (PSLV) to launch two specially designed satellites, each weighing approximately 220 kilograms, into a 470-kilometer orbit above Earth. These satellites, named ‘Chaser’ and ‘Target,’ will be docked and undocked using ISRO’s indigenously developed ‘Bhartiya Docking System.’ This docking system adheres to the International Docking System Standard (IDSS), developed by NASA, but is uniquely optimized with advanced features. Unlike the IDSS, which uses 24 motors, the Indian system achieves the same functionality with just two motors, demonstrating its sophisticated and efficient design.
The mission will slow the relative velocity of the satellites from 28,800 kilometers per hour to nearly zero—approximately 0.036 kilometers per hour or 10 millimeters per second—using specially designed rockets and sensors. This intricate maneuver will allow the two satellites to mate autonomously, forming a single spacecraft. The physics involved is extraordinarily complex, as the satellites must maintain their orbits while avoiding collisions. ISRO Chairman Dr. S. Somanath described the challenge as a “Herculean task,” but emphasized the critical importance of mastering docking technology for India’s future space missions.
The SpaDeX mission, a cost-effective technology demonstrator, lays the groundwork for advanced space objectives, including the Chandrayaan-4 mission, sample returns from the moon, the Bharatiya Antariksh Station (BAS), and India’s ambitious human spaceflight program. According to ISRO, the ability to dock spacecraft is essential for missions requiring multiple rocket launches to achieve shared objectives.
Designed by ISRO scientists, the SpaDeX mission’s satellite assembly and integration were carried out by Bengaluru-based Ananth Technologies, a private space technology firm founded by Dr. Subba Rao Pavuluri. Dr. M. Sankaran, Director of the UR Rao Satellite Center, commended the private company for its successful execution of this complex project.
This mission represents a leap forward in India’s space ambitions, with the Bhartiya Docking System paving the way for advanced docking ports capable of connecting the Gaganyaan Crew Module to the future Bharatiya Antariksh Station. The docking experiment is expected to be completed by early 2024, marking a new chapter in India’s journey as a leading spacefaring nation.
