arcs, and a secondary interstellar neutral atom stream), and answered a set of outstanding questions regarding the source region of kilometric continuum radiation, the role of solar wind pressure pulses in ionospheric outflow, and the relationship between proton and electron auroras during substorms. When the spacecraft went silent in December 2005, it had already been approved a mission extension until 2010. Costs for IMAGE are estimated at US$132 million, including the spacecraft, instruments, launch vehicle, and ground operations. Payload Its science payload consists of three suites of instruments: Energetic neutral atom imagers (LENA, MENA, HENA) — These instruments use hydrogen, helium, and oxygen atoms in the exosphere to form images and determine the properties of their low-, medium- and high-energy parent ions. HENA, the High Energy Neutral Atom imager is a modified version of the MIMI/INCA (Magnetospheric Imaging Instrument/Ion and Neutral Camera) sensor flown on the Cassini–Huygens mission. Ultraviolet imagers (FUV and EUV) — The extreme ultraviolet (EUV) imager detects light from helium atoms in Earth's plasmasphere. The Far ultraviolet (FUV) imager employs three detectors to image the auroras in different wavelengths and measure the distribution of different ions. Radio Plasma Imager (RPI) — This instrument uses pulses of radio waves to image the entire volume of the Earth's magnetic field. With its -long antenna, it sends out a burst of radio waves, which reflect off of clouds of charged particles between the plasmasphere's outer boundary all the way out to the boundary where the Earth's magnetic field is impacted by the solar wind. RPI also measures naturally occurring plasma waves at the spacecraft's location. The Central Instrument Data Processor (CIDP) as well as the Command & Data Handling Subsystem (main on-board computer) were built around the mission-proven IBM RAD6000 avionics processors. Experiments Extreme Ultraviolet Imager (EUV) The Extreme Ultraviolet Imager (EUV) of the IMAGE mission observes the distribution of He+ in Earth's plasmasphere by detecting its resonantly-scattered emission at 30.4-nm. It records the structure and dynamics of the cold plasma in Earth's plasmasphere on a global scale. The 30.4-nm feature is relatively easy to measure because it is the brightest ion emission from the plasmasphere, it is spectrally isolated, and the background at that wavelength is negligible. Measurements are easy to interpret because the plasmaspheric He+ emission is optically thin, so its brightness is directly proportional to the He+ column abundance. Effective imaging of the plasmaspheric He+ requires global