India’s space agency, ISRO, plans space docking experiment (SPADEX) next year, the agency’s Chairman, Kailasavadivoo Sivan, told Business Line today. Docking refers to connecting of two flying objects in space, either to transfer men or material from one to the other, or two join two structures to make a bigger one.

Two satellites would be sent to space on board a regular PSLV mission and the two would be made to dock with each other, Sivan said, describing the exercise as a technology demonstration experiment.

Mastering this extremely difficult technology is crucial for the operations of an Indian space station, a lab up in space—astronauts would need to be ferried from the earth to the space station and back. This can be achieved only if the vehicle carries the astronauts can dock with the space station.

Asked when ISRO planned to build a space station, Sivan said that the project was still some distance away, and would be taken up only after the Gaganyaan mission, which is to take astronauts to space and bring them back to earth safely, through the rigours of re-entry into earth’s atmosphere. Gaganyaan is expected to happen in December 2021.

Complex technology

Docking is broadly for two different purposes—for sending human beings from a shuttle to a space station, or for assembling large satellites in space. Each of these has different complexities. In the case of docking for human transfers, there is scope for human intervention if something goes wrong; when satellites mate in space to form larger structures, it all has to be done by using devices such as sensors and cameras.

Imagine two objects – satellites – flying in space at incredible velocities, of the order of 10 km a second. When they are a few kilometres away, they communicate with each other and the one in front slows down in order that the follower comes close. When they are close enough, onboard cameras (or, lasers) switch on and they ‘look’ at each other. Guided by camera, one latches on to the other and the two become a larger structure. This way, enormous structures can be built in space.

Elsewhere in the world, there are talks of space solar stations, which are giant solar power plants up in space which produce electricity from the sun and beam it down to earth in the form of microwaves.

Docking will be a key capability in future space operations and ISRO’s first step in that direction –SPADEX—will happen next year.