imagery is used for verification in arms control. Telemetry Intelligence TELINT is one of the "national means of technical verification" mentioned, but not detailed, in the Strategic Arms Limitation Treaty (SALT). This data can provide valuable information on the actual performance of the missile and especially its throw-weight, i.e. the potential size of its nuclear warheads. The treaty language "the agreements include provisions that are important steps to strengthen assurance against violations: both sides undertake not to interfere with national technical means of verification. In addition, both countries agree not to use deliberate concealment measures to impede verification." refers to, in part, a technical agreement not to encrypt strategic test telemetry and thus impede verification by TELINT. Electro-optical and radar sensors in verification Telemetry intelligence on a missile test is frequently combined with electro-optical intelligence and radar tracking from cameras on aircraft (e.g., US RC-135 COBRA BALL), ground stations (e.g., US Cobra Dane) and ships (e.g., US Cobra Judy, Cobra King, Cobra Gemini). Observed trajectories, speeds, etc., can be used to verify the TELINT information is accurate. Even though some of these techniques do take pictures, these, as a whole, are considered MASINT Methods continue to evolve. COBRA JUDY was intended to gather information on long-range missiles, in a strategic role. One developmental system, COBRA GEMINI, was intended to complement COBRA JUDY. It can be used for observing long-range missiles, but is also appropriate for theater-level weapons, which may be addressed in regional arms limitation agreements, such as the Missile Technology Control Regime (MCTR). Where COBRA JUDY is built into a ship, this dual frequency (S- and X-band) radar is transportable, capable of operating on ships or on land, and optimized for monitoring medium range ballistic missiles and antimissile systems. It is air-transportable to deal with sudden monitoring contingencies. Cobra Gemini was installed aboard around 2000. Cobra King was the Cobra Judy replacement that entered service on in 2014. Space-based Nuclear Energy Detection In 1959, the US started to experiment with space-based nuclear sensors, beginning with the VELA HOTEL satellites. These were originally intended to detect nuclear explosions in space, using X-ray, neutron and gamma-ray detectors. Advanced VELA satellites added devices called bhangmeters, which could detect nuclear tests on earth by detecting a characteristic signature of nuclear bursts: a double light flash, with the flashes milliseconds apart. These satellites also could detect electromagnetic pulse (EMP) signatures from events on Earth.