Kosmos 638 (Russian: Космос 638) was an uncrewed test of the 1975 Apollo–Soyuz Test Project Soyuz. It carried an APAS-75 androgynous docking system.

A crewed Soyuz 7K-TM as seen from Apollo module during the Apollo–Soyuz Test Project.

This was followed by another uncrewed test of this spacecraft type, Kosmos 672.[1] It was a Soyuz 7K-TM spacecraft.[1]

When the air was released from the orbital module (which is ejected before re-entry of the capsule) it caused unexpected motions with the spacecraft.[1] This led to the next test also being uncrewed.[1]

Mission parameters

  • Spacecraft: Soyuz-7K-TM №71
  • Mass: 6510 to 6680 kg
  • Crew: None
  • Launched: April 3, 1974
  • Landed: April 13, 1974


  1. ^ a b c d Rex Hall; David Shayler (2003). Soyuz: A Universal Spacecraft. Springer Science & Business Media. p. 211. ISBN 978-1-85233-657-8.