Iridium 77 Iridium 77 Iridium 77 is a communications Satellite which is part of a satellite constellation known as Iridium, named after the 77th chemical element of the periodic table, "iridium". It was launched in 1998 and as of 2014, operational. It is owned and funded by Iridium, a communications company. Iridium 77 is a part of a space-based communications system called Iridium. Conceived, designed, and built by Motorola, the Iridium system provides wireless, mobile communications through a network of 66 satellites in polar, low-Earth orbits. Inaugurated in November 1998, under the auspices of Iridium LLC, this complex space system allowed callers
History of the periodic table known as isotopes, from the Greek "" ("same place"). In 1914, a year before he was killed in action at Gallipoli, the English physicist Henry Moseley found a relationship between the X-ray wavelength of an element and its atomic number. He was then able to re-sequence the periodic table by nuclear charge, rather than by atomic weight. Before this discovery, atomic numbers were sequential numbers based on an element's atomic weight. Moseley's discovery showed that atomic numbers were in fact based upon experimental measurements. Using information about their X-ray wavelengths, Moseley placed argon (with an atomic number Z=18) before potassium