SpaDeX or Space Docking Experiment is a cost-effective technology developed by Indian Space Research Organisation (ISRO) for the demonstration of in-space docking using two small spacecraft.
When many rocket launches are required to achieve common mission objectives in-space docking technology comes in handy. With this initiative, India is progressing towards being the forth nation globally to have space docking technology.
The mission is scheduled on 30th December 2024 at 21:58 hrs IST from Satish Dhawan Space Centre SHAR (SDSC SHAR), Sriharikota.
The mission is one of the most awaited missions of ISRO because initially its preliminary studies done in 2016.
Objectives of SpaDeX Mission-
Primary Objective: Develop and demonstrate the technology needed for rendezvous, docking and undocking of two small spacecraft (SDX01: Chaser and SDX02: Target) in a low-Earth orbit.
Secondary Objective:
- Demonstration of the transfer of electric power between the docked spacecraft, which is essential for future applications such as in-space robotics.
- Composite spacecraft control
- Payload operations after undocking
Concept of SpaDeX Mission-
The SpaDeX mission consists of two small spacecraft (each having 220 kg mass) will be launched by PSLV-C60, both will be launched as co-passengers. Initially, both the spacecraft will be injected at 10-20 km inter-spacecraft distance into a 470 km circular low-Earth orbit at 55° inclination, with a local time cycle of about 66 days.
Now, the Target and the Chaser will be in the same orbit with equal velocity but separated by around 10-20 km, a phenomenon known as Far Rendezvous. Subsequently, the chaser will approach the Target with progressively shorter inter-spacecraft distances of 5km, 1.5km, 500m, 250m, 15m and 3m, eventually leading to docking.
Following successful docking and rigidisation, electrical power transfer between the two spacecraft will be demonstrated before undocking and separating the two satellites to begin functioning their individual payloads for the mission’s projected two-year duration.
New Technologies-
- Docking mechanism,
- A suite of four rendezvous and docking sensors,
- Power transfer technology,
- Indigenous novel autonomous rendezvous and docking strategy,
- Inter-satellite communication link (ISL) for autonomous communication between spacecraft, incorporated with inbuilt intelligence to know the states of the other spacecraft,
- GNSS-based Novel Relative Orbit Determination and Propagation (RODP) processor to determine the relative position and velocity of the other spacecraft,
- Simulation test beds for both hardware and software design validation and testing.
Significance of SpaDeX Mission-
The successful completion of SpaDeX will position India among an elite group of nations—the US, Russia and China—that possess space docking capabilities. This milestone will pave the way for ambitious projects like Chandrayaan-4, Bharatiya Antariksh Station (BAS) and Gaganyaan while enabling advancements in satellite servicing, space debris management and public-private collaborations. It underscores India’s expanding prowess in the global space technology ecosystem.