A Russian-based cooperative science space programme. It was established by the USSR in 1967 with members of Eastern European and other communist nations; each state financed its own experiments launched on Interkosmos satellites. Cosmonauts were selected from many of these nations for scientific missions. The first Interkosmos satellite was Vertikal 1, launched on 28 November 1970.

Following the break-up of the USSR, Western nations have participated in the programme, and Interkosmos joined the International Solar Terrestrial Programme with NASA and the European Space Agency in the 1990s to launch spacecraft to study the solar wind's influence on the Earth's magnetosphere. Interkosmos 26, launched on 2 March 1994 to study the Sun, included input from scientists in the UK and France.