Issued in 1978 to commemorate the Interkosmos cooperation program, this 35 Pfennig stamp celebrates the historic joint spaceflight between the USSR and the DDR. The design features a detailed space station/spacecraft assembly alongside the Interkosmos emblem, symbolizing socialist scientific collaboration. Below, a tribute to aviation pioneer Otto Lilienthal connects early flight experiments to modern space exploration. The crisp blue-red engraving and technical artwork give it strong thematic appeal. A desirable piece for Space, Cold War, and Aerospace topical collections.