There are six such strings. The Iridium system pioneered mass production of communications satellites. From an initial schedule of 12 to 18 months to build a spacecraft, the production line accelerated to a capability to completely fabricate a satellite every week. An Iridium satellite is about 3 feet by 11 feet and weighs about 1,300 lbs. And in one 13-day period we launched 14 satellites from three different countries.
Iridium is the name of a chemical element.
It was chosen for the satellite network because the initial deployment architecture called for 77 satellites, and Iridium's atomic number is 77. Although design improvements later reduced the satellite requirement to 66, by then the name had stuck. Another innovation of the Iridium system delighted amateur astronomers. Each satellite's highly reflective antenna arrays are pointed to the left and right of its path. In sunlight, the satellite acts like a signal mirror projecting a beam of light onto Earth's surface.