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| An Apollo–Soyuz cover commemorating the Russian cosmonauts’ visit to the Johnson Space Center as part of the Apollo–Soyuz Test Project, postmarked at Houston, Texas, with a hand cancel on July 9, 1973, signed by Alexei Leonov and Thomas Stafford.
Before the Apollo–Soyuz Test Project (ASTP) took place, American astronauts and Soviet cosmonauts visited each other’s space centers to gain familiarity with the other nation’s spacecraft. This is the first exchange that occurred in July 1973, when the Russian delegation toured the Johnson Space Center. |
1973-07-09 USA Soviet Cosmonauts Visit Johnson Space Center
