ISRO’s SpaDeX: Advancing India’s Space Exploration and Opens New Frontiers for Indian Defence

By R Anil Kumar

• ISRO’s SpaDeX mission represents a transformative leap in India’s space capabilities, with profound implications for national defence

• By enhancing satellite maintenance capabilities and supporting future missions, it positions India as a formidable player in both space exploration and military applications

Bengaluru, January 21. ISRO’s Space Docking Experiment (SpaDeX) has emerged as a significant milestone in India’s space capabilities, particularly with implications for national defence.

Successfully docking two satellites on January 16, 2025, marks India as the fourth country to achieve this advanced technology, following the United States, Russia, and China. This achievement not only enhances India’s standing in global space exploration but also opens new frontiers for its defence sector.

Significance of SpaDeX for Indian Defence

The successful docking operation is pivotal for the Indian military’s burgeoning space-based programs.

The Indian Air Force (IAF) had previously identified a need for Autonomous Docking Operations for On-Orbit Maintenance and Refuelling (OOMR), which is essential for maintaining and upgrading existing space assets.

The use of satellites for strategic reconnaissance has become increasingly vital since the Kargil conflict in 1999, highlighting the necessity for indigenous capabilities in satellite technology.

Key Benefits of SpaDeXfor Defence

Enhanced Operational Lifespan: The technology developed through SpaDeX allows for the refuelling and maintenance of satellites already in orbit, significantly extending their operational life. This is crucial as many geo-stationary satellites are costly and typically have a limited lifespan due to fuel depletion.

Support For Future Missions: The docking technology is integral to upcoming missions like Chandrayaan-4 and Gaganyaan, as well as plans for establishing a permanent Indian space station by 2035. These missions will require sophisticated coordination and control of spacecraft in orbit.

Development of a Satellite Constellation: India plans to launch a constellation of military satellites to enhance surveillance and communication capabilities. The successful demonstration of docking technology is a step towards realizing these ambitious projects.

Collaboration with Private Sector: The mission aligns with India’s New Space Policy, which encourages private sector participation in space endeavours. This collaboration is expected to accelerate innovation and development in defence-related space technologies.

Technological Implications

The SpaDeX mission demonstrates several critical technologies:

Rendezvous And Docking: The ability to bring two spacecraft together in orbit is a complex operation that requires precise control over relative velocities and positions.

Power Transfer: Future tests will explore power transfer between docked satellites, which could facilitate longer missions without the need to return to Earth.

In-Space Robotics: The mission lays the groundwork for developing robotic systems that can operate autonomously in space, essential for maintenance and repair tasks.

A top ISRO scientist had earlier told that a key spin off of the space docking technology would be extending the operational life of existing satellites.

Space assets like geo-stationary satellites are very expensive but have a life of 8 – 10 years when propulsion units run out of fuel even though other onboard systems and sensors are fully functional.

Space docking technology would enable replacing propulsion units repeatedly, allowing satellites to remain effective for many more years.

In November 2024, the IAF had projected a requirement through the Ministry of Defence’s Innovations for Defence Excellence (iDEX) scheme that ropes in the industry for meeting the Armed Forces’ requirements, for space docking technology.

“This project is about refuelling, maintenance and upgrading operations of a spacecraft, while in orbit, which entails the development of technologies for precise rendezvous, proximity and docking with the spacecraft and subsequent refuelling, maintenance and upgrading spacecraft operations,” the iDEX document stated.

“The expectation from the challenge is to design and develop technologies for docking operations with friendly/ cooperative spacecraft that need to be serviced, refuelled, or maintained.

The technologies for precise guidance during all phases of operation – proximity, terminal guidance and docking and subsequent docking methodologies are envisioned to be designed and developed in this challenge,” the document added.

As of 2024, India operates nine satellites for defence purposes. Among them, two GSAT-7 and GSAT-7A are dedicated military satellites, while the rest like HySIS, CartoSat, EMISAT, RISAT and EOS, are dual purpose satellites. Six more satellites that will have military applications are planned for launch soon.

After the retirement of the Soviet-era MiG-25R tri-sonic high-altitude reconnaissance aircraft that the IAF operated from 1981 to 2006, India depends upon satellites for strategic reconnaissance and imagery. The satellites are supplemented at the tactical level by unmanned aerial vehicles and fighter aircraft equipped with externally mounted camera pods.

In India, the Defence Space Agency (DSA), a tri-services agency under the Integrated Defence Staff headquartered at Bengaluru, is responsible for operating satellites and conducting space-warfare, including research, threat assessment, anti-satellite programmes and doctrinal aspects.

India’s foray into using outer space for military purposes began with the ‘Space Based Surveillance Phase – I’ project, which was approved by the Vajpeyee government in 2001.

As a part of this, four satellites — Cartosat-2A, Cartosat-2B, EROS-B and RISAT-2 — were launched. Space Based Surveillance Phase – II was approved in 2013, which saw six satellites — Cartosat-2C, Cartosat-2D, Cartosat-3A, Cartosat-3B, Microsat-TD, RISAT-2A — being put in space, according to reports.

In October 2024, the Cabinet Committee on Security approved a proposal for the development, construction and launch of at least 52 satellites as a part of Space Based Surveillance Phase – III for round the clock, all weather reconnaissance and surveillance from space across land and sea domains, as well as enhance secure communications capability.

The project estimated to be worth Rs 26,968 crore will be supervised by the National Security Council Secretariat along with the DSA. ISRO will construct 21 satellites while the remaining 31 will be built by the private sector.

Conclusion

ISRO’s SpaDeX mission represents a transformative leap in India’s space capabilities, with profound implications for national defence.

By enhancing satellite maintenance capabilities and supporting future missions, it positions India as a formidable player in both space exploration and military applications.

The successful docking not only underscores India’s technological advancements but also reflects its commitment to self-reliance in defence capabilities through innovative space technologies.