|Description:|| After the success of the Short Wavelength Spectrometer (SWS) on the Infrared Space Observatory (ISO), Astron's sister organization SRON Netherlands Institute for Space Reseach set out on the development of an instrument for the European Space Agency's fourth cornerstone mission Herschel. This instrument employs a heterodyne technique but now not at radio wavelengths but in the far-infrared. HIFI - the Heterodyne Instrument for the Far-Infrared is the most complex space research instrument ever built in the Netherlands. It consists of state-of-the-art Local Oscillators, state-of-the-art superconducting mixing devices and very novel Acousto-Optical Spectrometers and Autocorrelators, put together by a consortium of 24 institutes from 11 countries, led from Groningen. In my talk I will describe the development of the components as well as the science large international teams are going to conduct with HIFI. While Herschel (with HIFI) is going to be launched in 2009, detector research has already started for|
the SPICA mission, most likely to be the successor of Herschel. Also first developments have started for an interferometer in space FIRI/ESPRIT. I will briefly address these future missions.