The TIMED Spacecraft Power System Orbital Performance

1,2 was developed and is being operated by the Johns Hopkins University Applied Physics Laboratory. The spacecraft is an atmospheric remote sensing mission sponsored by NASA's Office of Space Sciences. The TIMED spacecraft is in a circular orbit at 625 km altitude and 74.4 degrees inclination. The mission is to study the influences of the sun and human activities on the Earth's thermosphere, ionosphere and mesosphere. The spacecraft was launched on December 7, 2001 on a DELTA II, a co-manifest launch with the French JASON spacecraft. The spacecraft serves as a platform for four instruments that measure the basic state parameters and energy balance of the Mesosphere, Lower Thermosphere and Ionosphere (MLTI), focusing on the region from 60 to 180 km in altitude. The Global Ultraviolet Imager (GUVI) is a nadir-pointing instrument; it measures the deposition of energy into this region from ultra violet wavelength of sunlight and particle precipitation into the polar aurora zone. The TIMED Doppler Interferometer (TIDI) gathers light using four telescopes pointing ±45 degrees from the velocity vector of the spacecraft. TIDI measures the wind velocities in this region. The Sounding of the Atmosphere using Broadband Emission Radiometry (SABER) instrument looks at the limb perpendicular to the TIMED spacecraft orbit plane on the cold side of the spacecraft and measures infrared emissions which are used to infer temperature and density of various atmospheric constituents. The Solar Extreme-ultraviolet Experiment (SEE) views perpendicular to the orbit plane on the sunward side and can move to view the sun at any elevation from the limb to directly overhead. It helps characterize the sun's energy input into this critical part of the earth's atmosphere.