Present and past space programs.

Space observations of binary stars are reviewed. It is noted that astrometric observations with greater accuracy than that obtainable from the ground could be made from satellites, but that no such program has been undertaken: the observations to date have concerned the astrophysical parameters of double stars, as deduced from radiation and spectrum measurements. Binary X-ray sources observed by Uhuru, OSO-7, Ariel-5, SAS-3, and OSO-8 are listed in a table with their orbital parameters and discussed. IUE observations of known binaries and discoveries of new binaries are surveyed, and the use of space X-ray and UV studies to investigate the nature of Sirius and Antares is described.