The first results from the Herschel-HIFI mission
  This paper contains a summary of the results from the first years of
observations with the HIFI instrument onboard ESA's Herschel space observatory.
The paper starts by outlining the goals and possibilities of far-infrared and
submillimeter astronomy, the limitations of the Earth's atmosphere, and the
scientific scope of the Herschel-HIFI mission. The presentation of science
results from the mission follows the life cycle of gas in galaxies as grouped
into five themes: Structure of the interstellar medium, First steps in
interstellar chemistry, Formation of stars and planets, Solar system results
and Evolved stellar envelopes. The HIFI observations paint a picture where the
interstellar medium in galaxies has a mixed, rather than a layered structure;
the same conclusion may hold for protoplanetary disks. In addition, the HIFI
data show that exchange of matter between comets and asteroids with planets and
moons plays a large role. The paper concludes with an outlook to future
instrumentation in the far-infrared and submillimeter wavelength ranges.
