Summary of the Scientific Goals
The following goals were those adopted at the time of, or in the case of the Tycho experiment soon after, the formal adoption of the project by ESA (i.e., around 1980).
*depending on galactic latitude and spectral type
Additional results on photometry, variability and double and multiple stars, not foreseen in detail at the time of the mission's acceptance, also appear as part of the final mission products.
The actual results (published as The Hipparcos and Tycho Catalogues) achieved by the mission in all case supersede these expected performances. The properties of the Catalogues are summarised here.