The U.S. Atomic Energy Detection System (USAEDS), a sensor system established in 1947, is capable of detecting “nuclear explosions that occur under land or sea, in the atmosphere or in space,” according to a July 12, 2011 Department of Defense news report. This detection system monitors three important nuclear treaties, the Limited Test Ban Treaty (1963), the Threshold Ban Treaty (1974), and the Peaceful Nuclear Explosions Treaty (1976), and is based out of the U.S. Air Force Technical Applications Center (AFTAC).
The news report states that USAEDS is comprised of sensors aboard over 20 satellites that are a part of the Global Positioning System and the Defense Support Program. This Defense Support Program has infrared-sensing satellites that are used to detect launches of intercontinental ballistic missiles and are equipped with sensors that “look for phenomenology from a nuclear explosion that occurs in space or in the atmosphere, whether it’s nuclear radiation or the flash from the fireball”, according to AFTAC chief scientist David O’Brien.
For underwater nuclear explosions, the USAEDS network employs five hydroacoustic stations that use underwater microphones to detect explosions and triangulate their location. The USAEDS network also contains seismic sensors to detect underground nuclear explosions that generate seismic activity very similar to an earthquake. To monitor above-ground explosions, infrasound sensors in the USAEDS network measure “changes in the atmosphere generated by…waves that can come from above-ground nuclear explosions”. Aircraft equipped with air sampling sensors collect debris from atomic tests and explosions to identify where the radioactive debris will travel. These sensors also collect radioactive gases and elements as indicators to where nuclear explosions have occurred.
The 1996 Comprehensive Test Ban Treaty (CTBT) contains a provision for the creation of an International Monitoring System (IMS) meant to identify treaty violations. The main obligation of the CTBT requires states parties to “not carry out any nuclear weapon test explosion or any other nuclear explosion, and to prohibit and prevent any such nuclear explosion at any place under its jurisdiction or control”.
The IMS is comprised of 337 facilities with seismic, hydroacoustic, infrasound, and radionuclide stations. Unlike USAEDS, however, IMS does not have satellite sensors. The United States was an active participant in the development of the IMS, and the USAEDS contributes data from its own stations to the IMS. All data obtained by the IMS is available to signatories of the CTBT.
According to AFTAC chief scientist O’Brien ,“both the IMS and ourselves are right at the state of the art of any technology that is practical for use in detecting nuclear explosions.”
The USAEDS network is an integral aspect of world nuclear explosion monitoring and has served as a leader for the development and implementation of IMS. USAEDS has detected and confirmed the most recent nuclear tests by Pakistan, India, and North Korea - all non-signatories of the CTBT.
Check out the Department of Defense news report here.