Explained: ISRO’s SpaDeX and its importance for India’s future space station

Indian Space Research Organisation (ISRO) on Monday night (December 30) successfully placed two satellites Spacecraft A (the “Chaser”) and Spacecraft B (the “Target”) in the right orbit of 475 km circular orbit, after over 15 minutes of flight.

This mission of ISRO is called SpaDeX (Space Docking Experiment).

What is SpaDeX?

SpaDeX includes an experimental docking of two satellites (Chaser and Target), their interlocking, pressure checks, and the undocking of both satellites.

“The PSLV-C60 mission placed the two SpaDeX satellites weighing 220 kg each in a circular orbit and the SpaDeX satellites have moved one behind the other, and over a period of time, it will pick up further distance, travel about 20 km away, and then the rendezvous and docking process will start,” said ISRO chairman S Somanath.

Also Read: PSLV C60 mission: Spacecraft put in right orbit, space docking in another week

Somanath said the docking process can happen in another week and the nominal time is going to be approximately January 7.

The two spacecraft would be merged together at an altitude of about 470 km after travelling at the same speed and distance.

Why is SpaDeX important for India?

Only three nations in the world currently have the capability to carry out docking of two spacecraft or satellites in outer space - the United States, Russia, and China.

India will join this elite club of nations with the success of this mission.

Also Read: ISRO to demonstrate docking of satellites in space in January; launch on Monday

This technology is essential for some of India's space ambitions like placing an Indian on the Moon, getting samples from the Moon (Chandrayaan-4 mission), and building and operating an international space station – the Bharatiya Antariksh Station.

In October this year, the government announced that India would have its own space station by 2035.

What are the main objectives of the SpaDeX mission?

According to ISRO, the main objectives of the mission are:

To develop and demonstrate the technology needed for rendezvous, docking, and undocking of two small spacecraft.

The demonstration of the transfer of electric power between the docked spacecraft, which is essential for future applications like in-space robotics.

Also Read: Sriharikota: PSLV-C60 lifts off with SpaDeX spacecraft

Composite spacecraft control, including remotely controlling it both in space and from mission control.

Payload operations after undocking.

Which are the other space stations?

There are only two space stations – the International Space Station (ISS) built by the United States and Russia, and the Chinese space station.

The American side of the ISS was built by NASA and the European Space Agency (ESA). The Russian side of the ISS was built by Roscosmos.

Also Read: ISRO to perform breathtaking acrobatics in space

The second space station, Tiangong Space Station, is being built by China.

Whenever astronauts travel to space and especially to the ISS, the shuttle or capsule they travel in has to perform a docking manoeuvre. After this is completed, and the two objects are interlocked, the astronauts enter the pressurised cabin of the space station.

What is the POEM-4 mission?

This mission also has the POEM-4 (PSLV Orbital Experimental Module 4) which has 24 payloads from startups, industries, academia, and ISRO centres to perform research and development.

Fourteen payloads are from the ISRO/DOS centres, and the remaining 10 payloads from non-government entities.

The payloads are going to be attached to the fourth stage of the PSLV rocket for conducting experiments over the next two months.

Also Read: ISRO India’s first-ever space docking: What is SpaDeX?

ISRO plans to experiment with microgravity during the PSLV rocket’s fourth stage. According to the space agency, this mission gives them the opportunity to conduct in-orbit microgravity experiments for an extended duration of up to 3 months.

One of the 14 ISRO payloads is of a robotic arm that will demonstrate the capturing of tethered debris in space. This robotic arm will be an important element in building India’s space station.