India's S-400 air defence systems demonstrated their dominance during 'Operation Sindoor', leaving Pakistan with no answer. The Pakistan Air Force (PAF) lost its Airborne Early Warning and Control (AEW&C) capabilities to its precision before the batteries, reportedly stationed at forward bases like Adampur, covered nearly the entirety of Pakistani airspace — forcing their fighter pilots to operate much further west. The S-400 was also used alongside the Akash and BrahMos systems to take out the ballistic missiles launched by Pakistan.
Thus, the Russian air defence systems remain central to India's capability to defend its territories during conflicts. India is reportedly in the middle of a project to successfully safeguard these systems from enemy radars. The S-400 emanates significant radar and thermal signatures, which can be identified by SAR satellites operated by the enemy. Its surveillance and engagement radars — along with the transporter-erector-launchers mounted on large 8×8 vehicle chassis — are all vulnerable to precision strikes. The best way to deal with the threat caused by S-400s is to take them out before the long-range interceptors can be launched. Thus, it is pivotal that India finds a way to hide its radar and thermal signatures from SAR satellites orbiting the Earth.
According to reports, S-400s cannot escape the surveillance of SAR satellites even if they are covered by standard camouflage nets. Even the mobility of the S-400 systems cannot guarantee absolute protection as frequent satellite passes happen every 60 to 90 minutes. This means movement must be ensured every hour or so, which may not be possible when things get complicated at the borders, the report added.
What are Synthetic Aperture Radar (SAR) satellites?
Synthetic Aperture Radar (SAR) is an advanced radar imaging technology that is capable of generating high-resolution images while airborne. SAR can operate from aircraft, drones, or satellites and can produce foolproof output 24/7, irrespective of weather conditions.
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Synthetic Aperture Radar sends out microwave radar signals and measures the echoes that bounce back from the Earth’s surface. The improved image resolution is credited to the synthetic aperture simulated by the satellite's motion, which acts as a very large antenna. Since they use radar waves, they are capable of seeing through clouds, smoke, rain, and fog, and do not depend on sunlight for output.
How SAR satellites work?
SAR can reveal terrain features, including mountains, rivers, and roads, alongside military infrastructure like buildings, trenches, bridges, airstrips, and convoys on the move. Therefore, enemy analysts can compare two images of the same location over two periods of time using SAR technology. If an area that previously showed nothing but trees and dust suddenly shows several bright metallic spots, it indicates that a mobile unit like an S-400 has moved into that position.
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Once a target is hit based on inputs from SAR satellites, they can also confirm whether targets were destroyed and detect if repairs or redeployments are under way, in addition to judging the intensity of the damage suffered. Since radar waves interact differently with metal, dug soil, or hidden structures, even fake targets set up to mislead enemies can be exposed, reports said.
Since the 8×8 vehicle chassis and other components of the air defence system are made of heavy metal, it creates a very bright "return" on a SAR image, as radar waves bounce off metal differently than they do off trees or soil. Specifically, if a SAR satellite spots an S-400 battery on the ground, its coordinates can be relayed within hours, making it prone to precision attacks. While the S-400 is mobile and can relocate quickly, frequent satellite passes (every 60 to 90 minutes) make it difficult to remain hidden for long periods.