The Herschel space mission

Herschel[1] was a spatial submillimetre observatory with spectroscopic and imaging capabilities covering the range from 55 to 671 μm (0.44 to 5.5 THz) partly explored for the first time here. With a primary mirror of 3.28 m (effective diameter) and a surface accuracy better than 6 μm, it will remain the largest telescope launched until the arrival of the James Webb Space Telescope end of 2018. The observatory was equipped with a dewar that contained 2367 liters of liquid Helium at launch in May 2009. Positioned at the 2
^nd
Lagrangian point, it functioned till April 2013. The telescope was passively cooled to 85 K. The total weight of the spacecraft was 3.4 tons at launch, including 315 kg for the mirror, 426 kg for the instruments and 335 kg of He. The payload was made of 3 instruments, 2 spectro-photometric cameras PACS [2] and SPIRE[3] equipped with bolometer arrays, and 1 heterodyne instrument, HIFI[4].