The Indian Space Research Organisation (ISRO) is advancing its capabilities in space operations with the planned SpaDeX-2 mission, which aims to dock two satellites in an elliptical Earth orbit—a significant step up in complexity from its previous success with SpaDeX-1 in a circular orbit.

SpaDeX-1, conducted in January 2025, saw two 220-kg satellites launched into a 470-km circular orbit, where they were separated, maneuvered, and then autonomously docked.

This mission demonstrated not only the ability to physically join the satellites but also to share power and operate as a single unit, marking India as the fourth country globally—after the US, Russia, and China—to achieve in-space satellite docking.

The accomplishment is crucial for future missions that require complex orbital assembly, such as the Chandrayaan-4 lunar mission and the proposed Bharatiya Antariksh Station, India’s planned space station.

The push for SpaDeX-2 is driven by the need to master docking in elliptical orbits, which are far more challenging than circular ones. In a circular orbit, a satellite’s trajectory and velocity remain constant, simplifying calculations and manoeuvres.

However, in an elliptical orbit, both trajectory and velocity change continuously, making real-time calculations and control far more demanding. This complexity mirrors the operational environment of many future Indian missions, especially lunar missions, where spacecraft are often inserted into elliptical orbits and gradually raised to higher altitudes to save fuel.

By developing and demonstrating docking in these more dynamic conditions, ISRO is preparing for missions that require multiple launches and in-orbit assembly—such as lunar sample return missions and the construction of a space station. These capabilities are essential for extending mission lifespans, enabling satellite servicing, and supporting human spaceflight ambitions.

SpaDeX-2 is currently in the planning and approval stage, with ISRO having submitted its proposal. If approved, the mission could launch within the next three years, further cementing India’s position in the elite group of nations with advanced space docking technology and enabling a new era of complex, multi-phase space missions.

ISRO