|HIFI Science Case|
The Far Infrared and Submillimetre Satellite (FIRST) is the fourth "cornerstone" in the European Space Agency's "Horizon 2000" programme. FIRST will be an orbiting facility class space telescope. In many ways it will be the submillimetre/infrared counterpart to the Hubble Space Telescope (HST). It promises to advance scientific understanding and make new discoveries equally as dramatic as those already achieved by the HST. The payload will consist of three instruments, two of which are imaging cameras for mapping the continuum in the far-infrared and submillimetre wavebands and each provides some limited low or moderate spectroscopic capabilites as well. The third instrument, HIFI, will make high resolution spectroscopic observations in the far infrared and submillimetre wavebands using heterodyne mixers based on superconducting tunnel junctions (SIS junctions) and Hot Electron Bolometers (HEBs).
The principal scientific goals of HIFI on FIRST revolve around various aspects of interstellar chemistry. Understanding the chemical processes in different environments and using a wide array of molecules as tracers of a variety of structures requires the observation of many molecular species. The far infrared and submillimeter wavebands are the best places to look for these molecules. The study of these molecules requires sensitive high resolution spectroscopy and that is what HIFI is designed for. As such, HIFI can be considered to be the primary instrument of the FIRST mission.
One area of interstellar chemistry that is of particular interest to Canadian astronomers is the study of water in the interstellar medium. Canadians scientists constitute a major part of the team building Odin, a satellite to be launched by a Swedish-Canadian-French-Finnish consortium later in 2000, which will study the 557 GHz spectral line of water. Water is a very important molecule in the interstellar medium and Odin will permit great advances in its study. However FIRST/HIFI will provide us with a huge advantage over Odin in being able to study dozens of water lines, with a great increase in sensitivity as well as an increase in spatial resolution. The high sensitivity of the SIS mixers will also allow FIRST to probe outside of our Galaxy, something which will be very difficult to do with earlier satellites such as Odin since they will use less sensitive Schottky receivers. Thus FIRST/HIFI is a natural and significant follow-on to research already underway in Canada. As well, opportunities to do new kinds of science will naturally follow from the availability of such a powerful new instrument.
for more science discussion, please see the HIFI Science site at the Space Research Organisation of the Netherlands.Mike Fich and Steve Torchinsky