Soyuz 9

The flight tested, for a longer period of time than any other, the capacity of the hardware and the human crew, on the long-term exposure to space conditions and observing (both visually and photographically) geological and geographical objects, weather formations, water surfaces, and snow and ice covers. The crew conducted observations of celestial bodies and practiced astronavigation, by locking onto Vega or Canopus, and then used a sextant to measure its relation to the Earth horizon. The orbital elements were refined to three decimal places by the crew.[1]

Commander Andriyan Nikolayev and flight engineer Vitaly Sevastyanov spent 18 days in space conducting various physiological and biomedical experiments on themselves, but also investigating the social implications of prolonged spaceflight. The cosmonauts spent time in two-way TV links with their families, watched matches in the 1970 FIFA World Cup, played chess (including this chess game with the crew as white; it was the first chess game played across space) with ground control, and voted in a Soviet election. The mission set a new space endurance record and marked a shift in emphasis away from spacefarers merely being able to exist in space for the duration of a long mission (such as the Apollo flights to the Moon) to being able to live in space. The mission took an unexpected physical toll on the cosmonauts; in order to conserve attitude control gas during the lengthy stay in orbit, Soyuz 9 was placed in a spin-stabilisation mode that made Nikolayev and Sevastyanov dizzy and space sick.[5]

• Mass: 6,460 kg (14,240 lb) [1]
• Perigee: 207.0 km (128.6 mi) [3]
• Apogee: 220.0 km (136.7 mi)
• Inclination: 51.70°
• Period: 88.59 minutes

The spacecraft soft landed in the steppes of Kazakhstan, and the crew was picked up immediately. Adjusting to gravity of Earth seemed to present a minor problem for the two cosmonauts.[1] They required help exiting the descent module and were virtually unable to walk for a few days.[5] Nonetheless, this experience proved the importance of providing crews with exercise equipment during missions. After landing the crew spend 2 weeks in a quarantine unit originally designed for cosmonauts returning from Moon landings.[5] While at the time the soviet press reported this was done in order to protect the cosmonauts in case space travel had weakened their immune system in practice its more likely it was practice for the Soviet crewed lunar program which at that point had not been abandoned.[5]

• Timeline of longest spaceflights