Thomas Stafford, astronaut who led rehearsal for 1969 moon landing

Communications challenges are common in space exploration but the first joint crewed mission between the United States and the Soviet Union brought its own unique difficulty.

Born and raised in small-town Oklahoma, the American commander, Tom Stafford, had a distinct drawl that his Russian counterpart, Alexei Leonov, found tricky to untangle. As they trained for the Apollo-Soyuz Test Project, Leonov joked that the mission involved three languages: English, Russian and “Oklahomski”.

Stafford, an experienced Nasa astronaut who was the commander on the dress rehearsal for the first moon landing, did not disagree. “Technically Apollo-Soyuz to me was somewhat simple,” Stafford told reporters in 2010. “But the most difficult thing of all the missions I flew was learning the Russian language. I knew that when I