What is SPADEX soon to be tested by ISRO? Here's all about Chandrayaan-4's backbone tech

After the success of Chandrayaan-3, ISRO is now busy developing technologies for the Chandrayaan-4 mission which will bring lunar rock samples back to Earth. Targeted for launch later this decade, the Chandrayaan-4 mission will involve complex in-orbit docking of spacecrafts in order to safely retrieve the lunar samples. 

This game changing technology will be tested during the SPADEX mission which is currently under development and its launch date is yet to be finalised.

All about the SPADEX mission

The SPADEX mission involves a spacecraft with two components - Chaser and Target - that will dock and separate as a mock drill for the Moon mission. While in the low-Earth orbit (LEO), the Chaser and Target will separate only to rendezvous autonomously later on.

This mission will aide the development of technology for Chandrayaan-4, which involves a sample module that will dock with another spacecraft in lunar orbit. The sample module will be filled with Moon rocks and regolith and it will join the re-entry module for a journey back to Earth.

A successful SPADEX mission will demonstrate ISRO's capabilities for in-orbit docking of two spacecrafts. As for the journey back to Earth, the agency already demonstrated that it can safely redirect a probe from the lunar orbit into an Earth-bound trajectory.

Earlier on December 4, ISRO announced that Chandrayaan-3's Propulsion Module which was in the lunar orbit since August has been transferred into the Earth's orbit using its leftover propellant (approximately 100 kg). The Propulsion Module will orbit the Earth for the next one year. 

"It was decided to use the available fuel in the PM to derive additional information for future lunar missions and demonstrate the mission operation strategies for a sample return mission," ISRO said in a statement.

ISRO also demonstrated its ability to lift off from the lunar surface after a touchdown with the Vikram lander's hop experiment in early September. The Vikram lander elevated about 40 centimeters from the surface and fired its engines to move about 30-40 cm from its landing point. The data gathered after this maneuver will aid ISRO in launching the sample module to the re-entry module. 

A successful SPADEX mission will also be used in development of the Bharatiya Antariksha Station (Indian Space Station). Speaking at an event in Ahmedabad on Friday, ISRO Chairman S Somanath said that the agency is targeting 2028 for the launch of the space station's first module. The multi-modular space station will be assembled over the next few years until the outpost is complete by 2035 and the SPADEX technology will have a big role to play.