광주흥신소 The missions and orbits of most spy satellites remain classified. But experts believe that modern visible-light cameras on U.S. satellites can, if conditions are right, read a license plate from space.
Such reconnaissance satellites gather data that analysts in centralized “factories” review for military and political purposes. But a delicate dance is underway about whether taxpayer dollars are being wisely spent or squandered.
Optical Imaging
Optical imaging satellites can see objects on the ground, even through clouds or in darkness. Often, the NRO will have several of these spacecraft overhead at any given time. They can’t read your house number, but they can tell whether a bicycle is parked in your driveway.
In the early days of satellite spying, wet film was used. The satellite took pictures, developed the film in orbit and transmitted TV scans back to Earth. That system was limited by the amount of film each satellite could carry, and it could take days, weeks or even months before people on the ground got a look at the images.
The first spy satellites to use digital cameras — the $1 billion KH-12s, for example — examined light in narrow bands of the electromagnetic spectrum, not just the visible one. That required multiple lenses, and each lens needed to be focused on a different wavelength.
Other types of spy 광주흥신소 satellites include polar-orbiting photoreconnaissance (POR) satellites that view a small, moving area of the surface at any given moment; infrared telescopes designed to detect missile launches and other events; and signals intelligence satellites (SIGINT), which are optimized for characterizing radar systems or for eavesdropping on communications. All of these satellites have sophisticated sensors and processing capabilities, which are continually improving to enable new capabilities.
Radar Imaging
Spy satellites have long used their powerful sensors to see what’s going on around Earth. They can scan the ground or track objects in the sky to gather information that might reveal the locations of a missile or a ship, for instance. They can also pick up the noises a country’s military makes as it moves vehicles and troops through its territory.
The US and its allies can now count between 339 and 485 military (or what’s referred to as “military-civilian”) satellites, depending on who you ask. These satellites, launched into secret orbits by space shuttles and Titan 4 rockets, are run by the National Reconnaissance Office headquartered in Chantilly, Virginia.
Some of these satellites, like USA-281, aka Topaz 5, can discern priceless details of a military’s infrastructure and weapons systems, even in the presence of clouds. This satellite, with its huge parabolic antenna that unfolds to a diameter of more than 100 meters, orbits at 36,000 kilometers (22,000 miles) high in a geosynchronous orbit along with commercial telecommunications satellites.
Radars work by sending out radio waves that hit the ground and are reflected back toward the satellite, where sensors detect the returning signal. During satellite design, engineers can optimize sensor parameters like wavelength and polarization to collect as much information as possible from the reflected signals, called backscatter. But even when the satellite’s view is clear, there can be geometric distortions, such as foreshortening. This happens because the radar-image plane is at an angle to the line from point A to point B, so slopes that are closer together appear steeper than ones that are farther apart.
Signals Intelligence
A satellite’s capabilities are not limited to imaging objects on the ground. Spy satellites can also record radio signals, allowing intelligence agencies to gather information on military activity and monitor communications. This technology, which is often referred to as “signals intelligence,” can be used for eavesdropping on enemy communications and to detect missiles being launched.
Spy satellites can also track ships and aircraft, even in clouds or darkness, thanks to advances in technology. They can also use sound sensors to capture the sounds of machinery operating, as well as a method known as synthetic aperture radar (SAR) to map the sea floor and identify moving targets on land.
SIGINT satellites are divided into three sub-fields: communications intelligence (COMINT, the interception of messages), electronics intelligence (ELINT, or identifying information about radar systems, jammers and other electronic devices) and telemetry intelligence (TELINT, or the recording of telemetry data from missiles). Some SIGINT satellites are optimized for specific activities. For example, a satellite called MIDAS was designed to intercept the signals of missiles being launched, while the Corona and SAMOS satellites followed polar orbits in order to see a large portion of the Earth at one time.
More than 2,500 satellites are in orbit around the planet, and many of them are used for nonmilitary purposes like monitoring natural disasters or providing satellite internet. But spy satellites are responsible for a fifth of the global fleet. The National Reconnaissance Office manages the United States’ collection of spy satellites. Its headquarters in Virginia and main analysis “factory,” the National Photographic Interpretation Center, are home to a secretive world of satellite imagery and radio intelligence.
Relay Satellites
Spy satellites are able to capture data and images from any point on the planet in near-real-time. This data is then transmitted back to ground stations, where it can be analyzed and used to detect enemy activity. The data collected by spy satellites can also be combined with information from other intelligence sources to provide a comprehensive picture of enemy activities on the planet.
Spy satellites can be equipped with a variety of different sensors, including cameras, radar systems and even signal-jamming technology. They can be programmed to collect data on a specific target or they can scan the entire planet for activity.
The satellites can also perform a variety of different maneuvers in orbit. This allows them to change their trajectory, altitude and inclination in order to mitigate the risk of being intercepted by potential adversaries.
While the capability of spy satellites can be incredibly useful, they have raised several ethical questions regarding their use and their impact on citizens’ right to privacy. Some governments have opted to be open and transparent about the use of spy satellites while others have chosen to remain silent.
While it is important to understand the capabilities of spy satellites, it is equally as vital to consider the impact they have on the world around us. By keeping an eye on the movements of nations, spy satellites have allowed us to see potential violations of international law before they become a threat or cause serious harm. This has helped to promote more peaceful relationships between countries and a more positive global environment.