A constellation of sixty-six operational satellites developed by Iridium Satellite, deployed between 2015 and 2017 in low-Earth polar orbit at an altitude of 780 km. They host government and scientific payloads, providing real-time visibility 24/7 over the entire Earth’s surface and atmosphere. This was augmented in 2013 by Iridium PRIME, which offers space on additional copies of the Iridium NEXT satellites, the first of which were launched in 2017.