Mint Primer: How do spy satellites work around the world?

Mint

15-05-2025

Spy satellites may have been used in the lead-up to the terror attack in Pahalgam, reports say. But India also uses such satellites through the Indian Space Research Organisation (Isro) and has ramped up their deployment. How do these sky-borne spooks really work?
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Are spy satellites common?
Yes. Most spacefaring nations have their own surveillance satellites that are operated by government-backed space agencies. The US National Aeronautics and Space Administration (Nasa) operates many types of surveillance satellites to do reconnaissance for military operations. In India, Isro's latest spy satellites include the Earth Observation Satellite (Eos) series, launched in 2020. A new Space-based Surveillance-3 (SBS-3) project seeks to put a constellation of surveillance satellites in orbit within the next four years to offer defence support in the interest of national security, Mint reported Monday.
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How do spy satellites really work?
Stationary satellites, which align with the earth's rotation, can be placed above a particular region. Low-earth orbit (Leo) satellites work as a constantly orbiting constellation, but relay information as a chain between each other, and subsequently to a ground station. These satellites have hyperspectral imaging cameras, which capture ultra-high resolution data of what lies below. For spy satellites, their imaging capability should be of the highest possible order—and their data transmissions are typically limited within a geography. To be sure, private surveillance satellite firms also exist.
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Do private firms offer surveillance too?
Sure. One such firm is homegrown satellite operator, Bengaluru-born Pixxel. Data from its satellite constellation can be bought for uses such as disaster management, conservation, etc. US firm BlackSky has been hired by French-Italian firm Thales Alenia Space to build a private surveillance service for Indian defence manufacturer, Nibe Ltd.
Can't surveillance satellites be hacked?
Theoretically, yes. All surveillance satellites carry sensitive data that is encrypted in various forms such as globally standardized Advanced Encryption Standard (AES), as well as more sophisticated forms. Data encryption is implemented in the broadcast of sensitive satellite data at a ground station level as well, while the satellites themselves would have geolocation restrictions in terms of the range of area within which the data is beamed from them. This is what primarily differentiates them from general-use earth image satellites.
So, public-private partnerships next?
Why not. India's new SBS-3 spying programme is using private firms to make the satellites. While the contract is closely monitored and controlled by the government and Isro, using private firms gives governments flexibility to make the most of surveillance data through analytics. In the long run, most governments plan to do this, since not every nation has its own satellites, let alone a space programme. Estimates peg the private satellite data industry globally to be worth $15 billion, driven by government contracts.