SSC Space US, Inc., formerly Universal Space Network, Inc., or USN[1] is an American company specializing in tracking, telemetry, and control of spacecraft. It is a subsidiary of Swedish Space Corporation, with four main sites and cooperative agreements with many others.[2] USN has been used by commercial satellite operations such as Sirius XM Radio[3] and scientific missions both in low Earth orbit (such as GALEX[4]) and in orbit around the Moon (such as Lunar Reconnaissance Orbiter[5]). USN has offered a 50% discount for their services for competitors for the Google Lunar X Prize.