GOES 15, also known as GOES-P, is an American (NOAA) geostationary weather satellite that was launched by a Delta 4 rocket from Cape Canaveral on 04 March 2010 at 23:57 UT. It is the third in an updated series of Geostationary Operational Environmental Satellites which carry an imager, sounder, the Solar X-ray Imager (SXI), the Space Environment Monitor System (SEM) and a search and rescue transponder which relays distress signals to the ground. The SEM consists of two magnetometers; an Energetic Particle Sensor (EPS) composed of a High-Energy Proton and Alpha Detector (HEPAD), a Magnetosphere Electron Detector (MAGED), an Energetic Proton Electron and Alpha Detector (EPEAD), and a Magnetosphere Proton Detector (MAGPD); Energetic X-Ray Sensor (XRS) and Extreme Ultraviolet (EUV) sensors. GOES 15 was placed in orbit originally as a spare and has an expected mission lifetime of 10 years (2 years on-orbit storage and 8 years operational).