Why in news? U.S. shot down a Chinese ‘spy’ balloon, days after the surveillance device was first spotted over American airspace captured global attention.

Highlights

• The spy balloon entered the air defence zone north of the Aleutian Islands and moved over land across Alaska and into Canadian airspace and crossed back into the U.S. over Idaho
• It is believed that Chinese surveillance tool carrying sensors and equipment to collect information about military and other strategic sites like Montana, home to one of the nation’s three nuclear missile silo fields.

What are spy balloons?

• Spy balloons are high-altitude surveillance tools that usually operate at 80,000-1,20,000 feet well above the cruising altitude of commercial aircraft to gather intelligence and carry out other military missions.
• Typically, this balloon are equipped with cameras and imaging devices suspended beneath the gas-filled white object to capture things of interest.
• Unlike satellites, balloons are economically viable.
• Due to their proximity to the Earth’s surface, they can widely scan an area from close quarters and capture clearer, high-resolution images of the target.
• The disadvantage is that these are not directly steered, but can be roughly guided by changing altitudes to catch different wind currents, and relatively easy target.