Isro’s SpaDeX: India successfully conducts historic space-docking test

S Somanath, who was Isro chief when SpaDeX (short for Space Docking Experiment) was launched and was monitoring its progress until his retirement a few days ago, had described docking as “a very complex process” that needed extreme precision and coordination.

To begin with, the two spacecraft had to be in the same orbit so that the Chaser could start to approach the Target.

On Thursday morning, scientists began by gradually reducing the speed of the two spacecraft – bringing them ever closer until they were just 3 metres apart. Then their connectors were latched together.

In the next step, the two spacecraft were screwed on perfectly, creating an airtight passage for safe transfer of material or crew, completing space docking.

An Isro official told the BBC that over the next two-three days, the mission will carry out what is being billed as one of its most important experiments – it will transfer electrical power from the Chaser to Target.

This, Ms Mitra, says is to demonstrate that a spacecraft can be sent to service another in space.

The experiment will then demonstrate “undocking and separation of the two satellites”.

Ms Mitra says the mission will also test India’s capabilities for inter-satellite communication as during the docking and undocking, the spacecraft will have to communicate with the Earth station and also with each other so that they know each other’s position and velocity.