Heterodyne Instrument for the Far Infrared (HIFI)

The principal scientific goals of HIFI revolve around various aspects of interstellar chemistry. Our understanding of the chemical processes in different astrophysical environments is advanced by observing many different molecules. The large-scale physical structures and chemical make-up can be mapped out by detecting the emissions from the molecules which form the gases in the interstellar medium. The far-infrared and submillimetre wavebands are the best places to observe these molecules. HIFI has been specifically designed to have the high spectroscopic resolution and sensitivity required to detect and analyze the emissions from a large variety of molecules.

The Canadian contribution to HIFI is the Local Oscillator Source Unit. An essential component of a heterodyne system is the reference signal that is mixed with the signal from the astronomical source. The reference signal is produced by a Local Oscillator. When the signal from the astronomical source is mixed with the reference signal, the result is a signal with a frequency much lower than the original signal, and therefore much easier to process with electronic circuits. Musicians are very familiar with this "heterodyne principal" when they tune their stringed instruments (pianos, violins, guitars, etc.) by listening for the "beat frequency." For HIFI, the reference signal must be extremely stable and pure. Canada's Local Oscillator Source Unit will be a frequency synthesizer of unprecedented precision and stability.

The Principal Investigator for HIFI in Canada is Professor Michel Fich of the University of Waterloo. For more information on HIFI visit the Herschel-HIFI website at the University of Waterloo.