India will not develop a large rocket for its planned crewed mission to the Moon, but instead, it will rely on multiple launches and satellite docking technology, according to ISRO’s current plans for the mission, aimed for 2040. “One option is to build a massive rocket to carry a single module, but then what do you do with the rocket afterward? Economically, we need to consider all factors. So, we won’t build a huge rocket. Instead, we plan to use multiple modules. Our current thinking is two modules, which will be launched separately and docked in space,” explained ISRO Chairman V. Narayanan in an interview. This strategy builds on India’s recent success with the Space Docking Experiment (SpaDeX) mission, which successfully completed its first docking maneuver on January 16. The mission involved two 220-kg satellites, initially separated by 11 km, orbiting at around 28,400 km per hour. Docking technology will play a crucial role in India’s upcoming space projects, including the planned space station with five modules and the crewed lunar mission. The space station modules will also be launched separately and assembled in orbit, with the first module already receiving government approval.
The technology ISRO is advancing through SpaDeX will offer valuable insights for future crewed Moon landing missions. While the successful first docking was a key milestone, ISRO plans to perform multiple maneuvers in various orientations to fully understand the dynamics involved. Each attempt will provide critical data that will help refine future space systems. Narayanan, who became ISRO chairman on January 13, described the complexity of docking: “Imagine two buses traveling at 100 km/h, and they need to dock. A lot of precision is needed—you have to come together within millimeters.”
The next docking phase will occur in mid-March. The satellites, once independently controlled, now function as a single unit. The next key step is establishing power transfer between the modules, essential for future missions like Chandrayaan-4, which will require multiple docking operations. Although ISRO has completed its first successful docking maneuver, SpaDeX will continue for a longer period. “The satellites are currently in an elliptical orbit, where power generation varies depending on their position. This is not a one-time operation. We’ll conduct multiple docking attempts to demonstrate our ability to perform the procedure reliably and consistently, starting in mid-March,” Narayanan said.
The main objectives include evaluating how precisely ISRO can perform multiple docking maneuvers, testing the performance of algorithms in various conditions, assessing the function of the integrated inertial systems, and monitoring the propulsion system during repeated operations. “This is a truly multidisciplinary effort. Through these repeated trials, we’ll gather extensive data to support future applications. Before conducting any real experiments, we test everything thoroughly in our ground simulator. We validate our approach through simulations first, and only proceed with the actual operation when we are completely confident. This careful method is crucial to avoid any mistakes,” he added.
ISRO’s approach emphasizes the collection of comprehensive data to refine the technology for future missions. While the first docking marked an important achievement, Narayanan indicated that the mission will extend over a longer period, with numerous experiments planned to perfect this complex capability.
