Defense Support Program (DSP)

The primary mission of the DSP satellite is to detect and report any intercontinental ballistic missile (ICBM) or sea-launched ballistic missile (SLBM) raids against the United States and its allies. Its secondary missions include space launch detection and nuclear detonation detection in support of international test ban treaties.

Development of the Soviet Union's first ICBM in the 1950s created a threat for which the U.S. had no in-place defense. The combination of man-made...