Bidspirit auction | Cosmonaut Vladimir Dzhanibekov signed NASA

Cosmonaut Vladimir Dzhanibekov signed NASA Shuttle Mission STS-39 Atlantis commemorative FDC. Dzhanibekov served on five space missions: Soyuz 27/Soyuz 26 (launch/return), Soyuz 39, Soyuz T-6, Soyuz T-12, and Soyuz T-13. He accrued 145 days, 15 hours, and 56 minutes in space over these five missions. He had also performed two EVAs with the total time of 8 hours and 35 minutes. In 1985 he demonstrated stable and unstable rotation of a T-handle nut from the orbit, subsequently named the Dzhanibekov effect. The effect had been long known from the tennis racket theorem, which says that rotation about an object's intermediate principal axis is unstable while in free fall. Good Condition Est.