What is orbital docking?

SpaDeX is the name of a new mission to be flown by the Indian Space Research Organisation (ISRO). During the mission, two satellites will be launched into orbit around the earth, where they will demonstrate the technologies to dock and undock while in motion.

ISRO needs to master in-space docking so that satellites launched in separate rocket launches can link up to perform more sophisticated tasks. The technology will be essential for the ‘Bharatiya Antariksh Station’, a new India-made space station ISRO has begun work on.

If the SpaDeX test is successful, India will become the fourth country in the world to have a space programme capable of docking in space.

The satellites for the SpaDeX mission will be launched onboard the PSLV C60 mission. ISRO is yet to announce the launch date, although it is expected to happen in December 2024.

Each of the spacecraft weighs about 220 kg. The rocket will launch them simultaneously but independently into a 470-km wide circular orbit at 55° inclination, with a local time cycle of about 66 days.

The docking manoeuvre will be SpaDeX’s primary objective. Once it has been accomplished, the two satellites will proceed to the secondary objectives: “the transfer of electric power between the docked spacecraft, which is essential for future applications such as in-space robotics; composite spacecraft control; and payload operations after undocking,” per an ISRO statement.

With agency inputs