Cosmonauts Pyotr Klimuk and Valentin Lebedev lift off aboard Soyuz 13, the second proving flight of the redesigned Soyuz spacecraft. Their eight-day-long stay in Earth orbit is a Soviet space program rarity: a flight devoted solely to scientific observations with no military objectives. Many of the science experiments were originally intended to be conducted on board the Salyut 1 space station. Much like the Skylab 4 crew, which is in orbit at the same time, the Soyuz 13 crew is able to observe Comet Kohoutek.
