16 January 2025, On Thursday early morning, the Indian space community celebrated the Indian Space Research Organisation (ISRO) successfully executing a crucial docking experiment, known as SpaDeX. India became the fourth country to accomplish such a feat, following the USA, Russia, and China.
SpaDeX, short for Space Docking Experiment, is a sophisticated mission crafted by ISRO. It involves two satellites — SDX01, also known as the Chaser, and SDX02, referred to as the Target. Weighing about 220 kg each, these satellites were launched together into space on December 30, 2024.
The SpaDeX mission aims to develop and fine-tune technologies related to space rendezvous, docking, formation flying, and other proximity operations. These technologies are critical for future missions, including human spaceflight, servicing satellites in space, and ensuring synchronized operations between multiple spacecraft. This capability means that in the future, India could send astronauts to space, repair or refuel satellites, and accomplish complex multi-satellite missions.
The journey to achieving this milestone was not without its challenges. Originally, the docking between the Chaser and the Target was planned for January 7, 2025. However, a few hiccups along the way postponed the event. Initially, ISRO scientists decided to delay the docking by two days to conduct “some more testing through simulations.” The second delay occurred due to a "glitch" encountered while trying to bring the satellites closer. Despite this setback, ISRO assured that both spacecraft were safe. This delay was necessary to analyze the situation thoroughly and make sure everything was perfect for the docking attempt.
On January 12, ISRO managed to reduce the distance between the Chaser and the Target from 15 meters to just 3 meters. This was a critical step, akin to two vehicles trying to match speed and trajectory before docking — precision and coordination were key.
Finally, in the early hours of January 16, the world watched as ISRO scientists executed the docking. To start, both satellites were initially launched into slightly different orbits. This strategy helped them build a distance of 10-20 km between them. Over time, and with calculated manoeuvres, scientists gradually reduced this distance.
On the docking day, the Chaser and the Target were manoeuvred to align perfectly with each other. The process involved gradually reducing their speeds, bringing them closer—first to 3 meters apart. This stage required not just careful planning but also significant skill in handling the spacecraft's positions and velocities. With less than three meters separating them, the satellite connectors latched together, creating a secure and stable connection. Following this connection, the two spacecraft were screwed together tightly to form an airtight passage. This passage is essential for potential future tasks like the safe transfer of material or even astronauts between the two satellites.
After a successful docking, the mission now looks forward to transferring electrical power from the Chaser to the Target. This step is important as it demonstrates the ability of one spacecraft to service another in space.
By successfully docking satellites, ISRO has demonstrated its capability to conduct complex space operations. This mission also showcases India's potential to participate more actively in international collaborations that require such sophisticated technology.
This research news was partly generated using artificial intelligence and edited by an editor at Research Matters
Editor's Note: The story was updated to update the graphic. No updates were made to the story. Any inconvenience is regretted.