We investigate the various forms of frozen water, such as in the interior of the Earth, in the interior of icy moons, on Saturn's rings or covering interstellar dust. There are 20 different crystalline forms of ice, plus three different non-crystalline, amorphous forms of ice. Two of these, ice XIX and VHDA, were discovered in our research group. Some of them, such as LDA or ice Ih, are ubiquitous in space. We know ice VI and ice VII from diamond inclusions from the interior of the Earth. Other forms are still undiscovered in nature - but temperature and pressure conditions suggest that some could be present on icy moons of Jupiter or Saturn, for example. We therefore support space missions such as JUICE or space telescopes such as the JWST by providing reference data, for example in the field of infrared and Raman spectroscopy.