​Gates in the sky: On ISRO and SpaDeX

On December 30, 2024, the Indian Space Research Organisation (ISRO) launched its PSLV-C60 mission. Its primary payload was a pair of satellites for the Space Docking Experiment, or SpaDeX, to demonstrate orbital rendezvous and docking. The ability to execute it in orbit is an essential stepping stone to more complex missions. The launch was also hailed as ISRO ending the year on a high, but SpaDeX reminded us that sophisticated spaceflight missions care little for arbitrary deadlines. The satellites successfully docked on January 16 after a few abortive attempts. They were expected to dock on January 7, which ISRO postponed to January 9, then brought them close without docking on January 12 in an apparent data-taking effort. It nixed the January 9 attempt after the satellites were found to have drifted more than expected, prompting measures to arrest the displacement and reinitialise the experiment. Once docked, ISRO began tests to verify if the satellites could exchange electric power, then undock and separate, followed by testing their own payloads that would be spread over two years. The C60 mission also launched the fourth stage of the rocket as an orbital platform. It carried 24 payloads from various ISRO centres and private enterprises testing various technologies. The Vikram Sarabhai Space Centre’s Compact Research module for Orbital Plant Studies was able to have cowpea seeds germinate in orbit, capturing the popular imagination.

Docking allows spacefaring components to be launched separately and assembled in space to form a larger module. This allows a space agency to plan interplanetary missions whose spacecraft are heavier than what the heaviest rockets can launch. Docking is thus a symbolic gateway to new opportunities, with the Chandrayaan-4 lunar sample return mission being a good example. In anticipation, ISRO loaded the SpaDeX satellites with enough fuel for multiple tries and also continuously collected data. Its own nervousness became evident, too: after the first two attempts, it backed down from its promise to live-stream the successful one. Docking technology has become desirable thanks to the perceived inevitability of long-duration spaceflight. The pressure to lower costs imposed by, say, crewed missions to Mars or space-mining operations has rendered ideas such as in-space satellite servicing and orbital resupply platforms, both of which require docking, more lucrative. ISRO plans to start launching the ‘Bharatiya Antariksh Station’ (BAS) later this decade. As it embarks on a new phase of operations, with V. Narayanan as its new chairman, ISRO should also describe a coherent vision for the ex ante utility expected of BAS. Without this context, the larger pieces of the Indian space programme and their purpose relative to other countries’ plans seem adrift.