millijanskys (mJy) and extended sources with brightnesses of around 500 mJy. The imaging camera had three bands, centred at 250, 350 and 500 micrometres, each with 139, 88 and 43 pixels respectively. It was able to detect point sources with brightness above 2 mJy and between 4 and 9 mJy for extended sources. A prototype of the SPIRE imaging camera flew on the BLAST high-altitude balloon. NASA's Jet Propulsion Laboratory in Pasadena, Calif., developed and built the "spider web" bolometers for this instrument, which is 40 times more sensitive than previous versions. The Herschel-SPIRE instrument was built by an international consortium comprising more than 18 institutes from eight countries, of which Cardiff University was the lead institute. HIFI (Heterodyne Instrument for the Far Infrared) A heterodyne detector able to electronically separate radiation of different wavelengths, giving a spectral resolution as high as R=107. The spectrometer was operated within two wavelength bands, from 157 to 212 micrometres and from 240 to 625 micrometres. SRON Netherlands Institute for Space Research led the entire process of designing, constructing and testing HIFI. The HIFI Instrument Control Center, also under the leadership of SRON, was responsible for obtaining and analysing the data. NASA developed and built the mixers, local oscillator chains and power amplifiers for this instrument. The NASA Herschel Science Center, part of the Infrared Processing and Analysis Center at the California Institute of Technology, also in Pasadena, has contributed science planning and data analysis software. Service module A common service module (SVM) was designed and built by Thales Alenia Space in its Turin plant for the Herschel and Planck missions, as they were combined into one single program. Structurally, the Herschel and Planck SVMs are very similar. Both SVMs are of octagonal shape and, for both, each panel is dedicated to accommodate a designated set of warm units, while taking into account the heat dissipation requirements of the different warm units, of the instruments, as well as the spacecraft. Furthermore, on both spacecraft a common design has been achieved for the avionics systems, attitude control and measurement systems (ACMS), command and data management systems (CDMS), power subsystems and the tracking, telemetry, and command subsystem (TT&C). All spacecraft units on the SVM are redundant. Power subsystem On each spacecraft, the power subsystem consists of the solar array, employing triple-junction solar cells, a battery and the power control unit (PCU). It is designed to interface