New Delhi:

Indian Space Research Organisation, the Indian space agency, succeeded in docking or mating two Indian satellites in space Thursday morning. This is part of the Space Docking Experiment or SpaDeX. This was the fourth attempt when Indian scientists finally hit Bullseye.

At about 10 am ISRO announced Docking Success. “Spacecraft docking successfully completed! A historic moment. Let’s walk through the SpaDeX docking process: Manoeuvre from 15m to 3m hold point completed. Docking initiated with precision, leading to successful spacecraft capture. Retraction completed smoothly, followed by rigidisation for stability. Docking successfully completed. India became the 4th country to achieve successful Space Docking. Congratulations to the entire team! Congratulations to India!”

SpaDeX Docking Update:

Docking Success

Spacecraft docking successfully completed! A historic moment.

Let’s walk through the SpaDeX docking process:

Manoeuvre from 15m to 3m hold point completed. Docking initiated with precision, leading to successful spacecraft capture.…

— ISRO (@isro) January 16, 2025

Docking is a very complex process and ISRO attempted it cautiously doing several trials over a fortnight.

India used the indigenously developed Bhartiya Docking System to achieve this feat just before docking the satellites moved closer to each other at a speed of 10 millimeters per second.

ISRO succeeds in docking two Indian satellites in space orbiting at 475 kilometers above Earth. India becomes the fourth country after Russia, USA and China to have successfully learnt to dock. India launched the SpaDeX mission on December 30, 2024 using the PSLV rocket. Docking is an enabling technology for future missions like Chandrayaan-4 and Bhartiya Antariksha station.

On January 12, 2025, when the last attempt was made, the satellites were moved back and forth to achieve what ISRO had described as an “exciting handshake” of the two satellites in space.

Then two Indian satellites came as close as three metres in a trial attempt for space docking and are now moving back, the Indian space agency said this morning.

“A trial attempt to reach up to 15 m and further to 3 m is done. Moving back space crafts to a safe distance. The docking process will be done after analysing data further,” the Indian Space Research Organisation (ISRO) said in its last update of January 12, on the Space Docking Experiment (SpaDeX) mission.

Docking is a very complex process with the satellites being moved back and forth to achieve what ISRO has described as an “exciting handshake” of the two satellites in space.

The SpaDeX mission was launched on December 30 with the satellites, SDX01 (Chaser) and SDX02 (Target), being lifted off onboard a PSLV C60 rocket and placed into a 475-kilometre circular orbit.

Prime Minister Narendra Modi took to social media X (formerly Twitter) and congraulated scientists at ISRO and the entire space fraternity for the successful demonstration of space docking of satellites. “It is a significant stepping stone for India’s ambitious space missions in the years to come,” he said.

Congratulations to our scientists at @isro and the entire space fraternity for the successful demonstration of space docking of satellites. It is a significant stepping stone for India’s ambitious space missions in the years to come.

— Narendra Modi (@narendramodi) January 16, 2025

New Delhi:

There is a traffic jam in space! It has forced the Indian Space Research Organisation (ISRO) to postpone the launch of the Polar Satellite Launch Vehicle (PSLV) by two minutes. Earlier, the PSLV-C60 that would launch the SpaDeX mission or the Space Docking Experiment was to be launched at 9.58 pm, but now it has been pushed to 10 pm.

The launch has been postponed due to “conjunctions with other satellites in the same orbit”, Dr S Somanath, Chairman of ISRO, told NDTV.

This is not the first time ISRO has had to reschedule its launch due to congestion in the orbit and flight path of the rocket.

Experts at ISRO found that some satellites from the Starlink constellation were coming in the way. Today, there are about 7,000 Starlink satellites in the low Earth orbit. This is a constellation owned by American billionaire Elon Musk and his company SpaceX. Starlink provides satellite-based broadband internet connectivity across the world. Ultimately, the total number of Starlink satellites is expected to go up to about 12,000.

Also Read | ‘SpaDeX’ Mission: How ISRO Will Dock Two Satellites In Space

For long, scientists and engineers from many space agencies have been complaining that these massive constellations will cause traffic jams in space. On top of that, there is the presence of space debris in copious amounts that also poses a huge risk to satellites.

In 2023, India had to postpone the launch of its Chandrayaan-3 mission by a few minutes almost for the same reasons.

The SpaDeX Mission

The PSLV C-60 mission has innovation written all over it, with the rocket and the satellites integrated and tested for the very first time at a private entity, Ananth Technologies. At the Satish Dhawan Space Center, Sriharikota, the rocket was also assembled in a new facility. Further, the space docking experiment is a big bold innovative step that will pave the way for its use in futuristic missions like Chandrayaan-4 and the making of the Bhartiya Antariksha Station.

In addition, the fourth stage of the PSLV which usually turns into space debris has been converted into an active un-crewed space laboratory. The last stage of the rocket has been re-purposed to become an orbital laboratory and from robotic experiments to growing cowpea seeds to testing green rocket fuel all will be tested on the PS4-Orbital Experiment Module, designated as POEM. It is carrying 24 experiments in space including taking three live biology experiments for the very first time by India.

India’s space program is set to achieve another milestone with the Space Docking Experiment (SpaDeX) on its 62nd Polar Satellite Launch Vehicle (PSLV) mission. ISRO will attempt the docking and undocking of two satellites in orbit, a feat mastered only by Russia, the United States, and China.

This landmark mission, described as a “bold step” by ISRO Chairman Dr S Somanath, will use indigenous technology.

“When you have multiple objects in space that need to be brought together for a specific purpose, a mechanism called docking is required. Docking is the process by which two space objects come together and connect. This can be done using various approaches: soft mechanisms, hard mechanisms, or pressurized compartments for human transfer. For example, on the International Space Station, crew modules dock at the station, equalize pressure, and transfer people,” Dr Somanath told NDTV.

This capability is central to future ambitions, including India’s Bharatiya Antariksha Station (a proposed Indian space station), human spaceflight programs, and lunar sample return missions such as Chandrayaan-4.

During docking, there is a “target” object and a “chaser” object. The chaser follows the target, comes into proximity, and establishes a connection.

With the SpaDeX mission, India aims to join the exclusive club of nations capable of space docking.

“The success of this mission will position India as a major spacefaring nation, not just in launching satellites but in conducting complex space operations,” Dr Somanath said.