Soyuz 31 carried Valery Bykovsky and Sigmund Jähn, the first German cosmonaut, into space.

Cosmonauts Bykovsky and Jähn were greeted by resident crew Vladimir Kovalyonok and Aleksandr Ivanchenkov when they docked at the aft port of the Salyut 6 space station the next day.

The visitors brought with them fresh onions, garlic, lemons, apples and other food for the long-duration crew, then in space for more than two months.

On September 2, the engines of Soyuz 29 were tested, 25 experiment containers with 100 experimental results were transferred, along with exposed film, and seat liners and centering weights were exchanged.

With this and subsequent flights, the landing occurred during the orbit which provided the nominal launch opportunity.