The increase in accuracy of astrometric results has been very limited in the last half century, and improvements of more than about a factor of 3 at best for ground-based observations are not expected for the next two decades. This is largely due to well known error-sources connected with the Earth atmosphere. By moving the observing equipment to a platform aboard a satellite many of these errors would disappear completely, or to a large extent. Unfortunately till now no space astrometric project has been realised. Consequently there are no astrometric observations of visual binary stars from space. Of course, the astrophysical parameters of double stars are as important as their astrometric data. A large number of double stars has been observed from space by measuring their radiation and spectra in different wavelengths regions not attainable from ground based telescopes. A good example is HZ Hercules (Her X-1).