science · Completed
SpaDeX
Two small satellites that found each other in orbit, docked, transferred power, and undocked: the capability every station and sample return needs.
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Docking is the prerequisite for almost everything ambitious in spaceflight: assembling a station, refuelling a tug, returning a sample from another world. Before SpaDeX, four entities had demonstrated it. India is now the fifth.
SDX-01 and SDX-02 were deployed by PSLV-C60, drifted apart, then closed the gap under their own control and mated on 16 January 2025. A second docking followed, with electrical power transferred across the interface, proving the connection was structural and functional rather than merely mechanical.
The same PSLV fourth stage stayed useful after separation: as POEM-4, it operated as an orbital platform and completed a thousand orbits before atmospheric re-entry.