India’s space agency is building out a nationwide network of sensors to track satellites and debris in Low Earth Orbit a belt of space growing dangerously crowded. ISRO confirmed in its Indian Space Situational Awareness Report (ISSAR) 2025 that it is setting up an optical telescope at Hanle, Ladakh, and working to install an indigenously developed phased array radar in India’s northeast. A national-level expert committee completed the design and review of the radar in 2025. Additionally, the Baker Nunn Schmidt Telescope (BNST) at Nainital being refurbished in collaboration with ARIES is expected to further strengthen tracking capability soon.
ISRO’s existing Multi-Object Tracking Radar (MOTR) at Satish Dhawan Space Centre, Sriharikota, currently anchors its tracking operations. The L-Band Active Phased Array Radar can simultaneously track multiple objects with a radar cross-section as small as 0.25 square metres at ranges up to 1,000 km.
Why Ladakh, Why the Northeast
Radars work around the clock, using reflected radio waves to pinpoint object positions. Optical telescopes, however, are limited to nighttime use and require unobstructed, dark skies making the high-altitude cold desert of Ladakh an ideal site. These telescopes detect satellites by capturing sunlight reflected off them.
A mix of both sensor types is essential for Space Situational Awareness (SSA) the continuous process of tracking, monitoring, and predicting the positions of satellites and debris to prevent collisions and protect space assets. Since any single ground station can only see a satellite for a brief window as it passes overhead, coverage demands multiple stations spread across strategic locations globally.
Collision Risk Is Rising
ISRO currently operates 53 satellites 22 in Low Earth Orbit (500–1,000 km altitude) and 31 in Geosynchronous Earth Orbit (approximately 36,000 km). The threat environment around them is intensifying.
According to ISSAR 2025, the Combined Space Operations Center (CSpOC) of US SPACECOM issued 1,50,000 close-approach alerts last year, warning operators when objects pass within dangerously close proximity. Objects in Low Earth Orbit travel at roughly 28,000 kmph at that velocity, even a small debris fragment can trigger a cascading chain of collisions.
In response, ISRO executed 18 collision-avoidance manoeuvres in 2025: 14 for LEO satellites and 4 for those in geosynchronous orbit. Among them was the $1.2 billion NASA-ISRO Synthetic Aperture Radar (NISAR) satellite. A collision-avoidance manoeuvre involves firing a satellite’s thrusters to shift its orbit when collision probability crosses a safe threshold.
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