ISRO gears up for SpaDeX mission to demonstrate space docking technology

The Indian Space Research Organisation (ISRO) is gearing up to end 2024 with a milestone mission—SpaDeX (Space Docking Experiment). Scheduled for launch on December 30 at 9:58 PM from Sriharikota, this mission will demonstrate in-space docking using two small spacecraft deployed by a PSLV rocket. The success of SpaDeX is seen as crucial for India's future space endeavours, including lunar sample return missions, the Bharatiya Antariksh Station (BAS), and crewed lunar expeditions.

The spacecraft for this mission has been developed at ISRO’s UR Rao Satellite Centre in Bengaluru. Its director, M. Sankaran, provided insights into the mission during an interview with CNN-News18.

Paving the Way for Space Docking

With the SpaDeX mission, India aims to join the elite group of nations with space docking capabilities. Explaining its importance, Sankaran remarked, “Docking basically is making two independent objects come together and join together and behave as if they are a single object. It is important for crewed missions to the moon or other planets; it’s not possible to achieve without docking technology.”

He noted the economic advantages of developing docking technology, particularly given ISRO's comparatively smaller launch vehicle capacity. The agency's approach minimizes costs while achieving ambitious goals, unlike high-capacity missions such as NASA’s retired Saturn V rocket program.

How SpaDeX Will Work

SpaDeX will involve two small spacecraft, Chaser and Target, being released into the same orbit. These spacecraft will initially be separated by a significant distance, which will be gradually reduced through carefully controlled manoeuvres.

Sankaran told News18: “From 20 km, we will bring the distance to 10 and 5 meters and allow it to dock. The whole activity will happen in 10-15 days from the time of the launch.”

This demonstration will also test essential sensors, algorithms, and software required for future missions, such as Chandrayaan-4.

A successful SpaDeX demonstration will signal India's mastery in autonomous space docking, a critical step for missions that lack GNSS support from Earth. Sankaran pointed out: “Chandrayaan-4 has been designed in such a way that docking is an essential technology available for that. This demonstration will give us confidence.”

In addition, docking technology will enable the assembly and operation of the Bharatiya Antariksh Station, where modules and supplies must be interconnected.

Economic Feasibility and Challenges

Known for cost-effective missions, ISRO has allocated ₹125 crore for the spacecraft and another ₹250 crore for the launch vehicle. However, developing compact spacecraft posed challenges.

Sankaran highlighted the complexities: “The challenge of docking using a very small spacecraft is that the inertia of the spacecraft is very small. Even a small disturbance will make the satellite move away. Low mass and low inertia mean a small force can disturb it," as quoted by News18.

Despite these challenges, ISRO remains confident, riding high on the success of Chandrayaan-3. Reflecting on the global recognition ISRO has garnered, Sankaran concluded, “The success of Chandrayaan-3 has made people turn back and look at ISRO and India with renewed interest. The ability of India and Indians will be once more demonstrated to the whole world.”