Haystack Observatory in Westford, Massachusetts, is an MIT-owned radio science center that brings together astronomy, atmospheric and ionospheric research, space surveillance, and related facilities on one campus. Built beginning in 1960 as the Haystack Microwave Research Facility for the United States Air Force, it entered operation in 1964 and passed to MIT in 1970. Its Haystack Radio Telescope, first used for space tracking and communications, later became a major astronomy instrument and a precise radar for tracking satellites and other orbiting objects. The site also includes the Westford Radio Telescope, the Millstone Hill Geospace Facility, and an important computing role in black hole imaging through the Event Horizon Telescope.