SpaDeX Mission
ISRO’s SpaDeX Mission India The Indian Space Research Organisation (ISRO) is set to launch its SpaDeX mission aboard the PSLV-C60 rocket, marking a significant milestone in the development of in-space docking technology.
This mission will demonstrate the ability to dock two small spacecraft, a key advancement for future space endeavors including lunar missions, the establishment of the Bharatiya Antariksh Station (BAS), and more. With this breakthrough, India aims to join the exclusive group of nations capable of in-space docking.
The SpaDeX mission serves as a cost-effective technology demonstrator, showcasing in-space docking using two small spacecraft, which are launched together via PSLV. This technology is vital for achieving India’s space aspirations, such as exploring the Moon, returning lunar samples, and building and managing the Bharatiya Antariksh Station (BAS).
In-space docking is essential for missions that require multiple rocket launches to meet common objectives. By successfully demonstrating this technology, India will become the fourth country globally with the capability to dock spacecraft in orbit.
Mission Objectives
The primary goal of the SpaDeX mission is to develop and demonstrate the technology required for the rendezvous, docking, and undocking of two small spacecraft (SDX01, the Chaser, and SDX02, the Target) in a low-Earth circular orbit.
Secondary objectives include:
- Power transfer: Demonstrating the transfer of electric power between the docked spacecraft, a key requirement for future in-space operations such as robotics.
- Spacecraft control: Demonstrating composite spacecraft control.
- Payload operations: Managing payloads post-undocking.
Mission Concept
The SpaDeX mission consists of two small spacecraft, each weighing approximately 220 kg. These will be launched by PSLV-C60 into a 470 km circular orbit at a 55° inclination. The orbit will follow a local time cycle of approximately 66 days.
The PSLV’s precision will create a slight relative velocity between the Chaser and Target spacecraft at the time of separation from the launch vehicle. This incremental velocity will allow the Target spacecraft to gradually move to a 10-20 km distance from the Chaser over a day. Using its propulsion system, the Target will compensate for the relative velocity, ensuring both spacecraft end up in the same orbit with identical velocities but separated by about 20 km — a phase known as Far Rendezvous.
Following this, the Chaser will approach the Target in stages: first reducing the separation to 5 km, then 1.5 km, 500 m, 225 m, 15 m, and finally 3 m, before achieving a successful docking.
Once docked, the two spacecraft will transfer electrical power, after which they will undock and separate to commence their respective payload operations. The spacecraft will operate for an expected mission life of up to two years.
Given its smaller size and mass, SpaDeX presents unique challenges. The precise maneuvers required for rendezvous and docking are more demanding than those for larger spacecraft. This mission will also lay the foundation for autonomous docking in future lunar missions, such as Chandrayaan-4, which will not rely on Earth-based GNSS.
ISL-Enabled GNSS-Based RODP
Both SpaDeX spacecraft are equipped with a differential GNSS-based Satellite Positioning System (SPS), providing Position, Navigation, and Timing (PNT) solutions. A novel RODP processor within the SPS receiver allows precise determination of the relative position and velocity between the Chaser and Target spacecraft.
Spacecraft Development
The SpaDeX spacecraft were designed and developed by ISRO’s UR Rao Satellite Centre (URSC), with assistance from other ISRO centers, including VSSC, LPSC, SAC, IISU, and LEOS. The spacecraft will be controlled during its orbital phase from ISTRAC using ISRO ground stations and additional external ground stations.
The full integration and testing of the spacecraft were completed by Ananth Technologies, Bangalore, under URSC’s supervision. After successful testing and clearance, the spacecraft has moved from URSC to SDSC for final launch preparations.
more stories
New Realme 14X vs iQOO Neo 10 Pro: Comparison Test 2025