흥신소 Designed to see beyond national borders, spy satellites are essential to military operations and the formation of national policy. They also play an important role in verifying arms control treaties.
Originally, spy satellites took pictures on film and dropped the canisters of film back to Earth in capsules that were retrieved by aircraft. Later, they used digital imaging systems.
At any given time, there are several black and white spy satellites circling overhead. These are optical-imaging satellites with light sensors that can detect missile launches and “see” enemy weapons on the ground. They are also able to detect radar waves emitted from any country on the planet, even through clouds. And they can also pick up signals from cell phones, which are essentially super-sophisticated radio receivers that are used to scour the dark web for terrorist activity.
Unlike those early spy satellites that tended to die after three or four weeks, and were limited in the amount of film they could carry, today’s satellites can last for years. They are still constrained, however, by the rate at which they can transmit their digital images back to Earth, as well as the number of opportunities they have to acquire images of a single target.
Optical reconnaissance satellites are vulnerable to jamming and component damage of various sorts, but the exact nature of these vulnerabilities depends largely on a particular satellite’s design. And for this reason, it is not easy to make general statements about the threats that adversaries may face if they wish to disable American spy satellites.
The radar system aboard a reconnaissance satellite transmits powerful radio waves toward Earth. When the waves hit a moving object, they bounce back toward the satellite and produce electronic images of the object that can be captured by the sensor on the satellite. Radars can see through clouds and operate at night, making them a valuable tool in intelligence missions.
The National Reconnaissance Office has issued contracts to five companies with synthetic aperture radar capabilities as the agency continues to examine how commercial radar can be integrated into its missions. The NRO has declined to disclose the value of the contracts.
These radars can detect and track objects, including ships, missiles, aircraft and even bat swarms at dusk. However, it is difficult to determine what is being tracked if the object is moving slowly, for example, an aircraft flying over the ocean. To solve this issue, the sensor tracks produced by the radar are fused into a single, more accurate system track that indicates the type of target and its velocity.
While radars can provide useful information, they are not a replacement for electro-optical imaging systems. As one US defense official put it in the 1970s, “The weather in the Soviet Union is crappy all the time, so getting a good picture of an object there can take years.” Developing a radar that could persist over the globe and provide persistent situational awareness would have been a significant step forward.
Increasing cases of technology misuses by various terror groups have triggered the need for strong signals intelligence techniques. As a result, the signals intelligence market is expected to grow rapidly in the coming years.
The term “SIGINT” stands for signals intelligence and is used by military or intelligence agency professionals to refer to information gathered using electromagnetic interceptions from foreign instruments. This includes data from radar systems and weapons. Historically, the field was comprised of two key areas: communications intelligence (COMINT) and electronic signals intelligence (ELINT).
SIGINT is a very broad intelligence discipline with many sub-fields. It encompasses tasking, collection and processing — and is one of the Intelligence Community’s primary sources of information about threats to national security.
Tasked intelligence activities are designed to provide the intelligence necessary for national security priorities. Targeted collection may be authorized only after validation of the intelligence priority and a determination – by an element of the Intelligence Community or an interagency committee consisting in whole or in part of the heads of elements of the Intelligence Community or the heads of departments containing such elements or their designees — that the information necessary to advance the validated intelligence priority cannot reasonably be obtained by other means.
Despite the growing threat of terrorism, there are still a number of limitations that limit how much the NSA can do with its SIGINT capabilities. For example, it’s impossible to intercept conversations at the highest possible levels of security if people are talking in public and on short-range unlicensed radios.
A relay satellite transmits data between non-geostationary communication platforms in orbit and the ground. This is a critical part of an in-space communications network. Relay satellites are essential to human spaceflight missions and remote science missions, such as NASA’s Europa Orbiter, which has a limited lifetime due to the harsh radiation environment and will not be able to transmit all of its scientific data directly to Earth during its 60-day mission.
To overcome this limitation, the European Space Agency launched a constellation of four MEO optical/RF relay satellites, called SpaceLink, which will be able to transform real-time information collected by satellites into a valuable resource for Earth and space users. MEO relay satellites enable LEO satellite operators to have low-latency, always-on access to their data, visitors to commercial space stations to have continuous communication capability and on-orbit servicers and tugs to receive maneuvering instructions any time.
However, despite the high reliability of the multi-satellite relay system in SIN, the capacity performance of the transmission can be improved by increasing the number of DRSs. This is because a DRS can simultaneously use the SN’s laser antenna, which means that it is able to receive multiple signals transmitted by multiple PSs. In this paper, a model and resource optimization algorithm for the multi-satellite relay transmission in SIN are proposed.