Enlarge / Apollo commander Tom Stafford (left) with Soyuz commander Alexei Leonov during the Apollo-Soyuz mission in July 1975. (credit: NASA)

Former NASA astronaut Thomas Stafford, a three-star Air Force general known for a historic handshake in space with a Soviet cosmonaut nearly 50 years ago, died Monday in Florida. He was 93.

Stafford was perhaps the most accomplished astronaut of his era who never walked on the Moon. He flew in space four times, helping pilot the first rendezvous with another crewed spacecraft in orbit in 1966 and taking NASA’s Apollo lunar landing craft on a final test run before Neil Armstrong and Buzz Aldrin set foot on the Moon in 1969.

By his own account, one of the greatest moments in Stafford’s career came in 1975, when he commanded the final Apollo mission—not to the Moon but to low-Earth orbit—and linked up with a Russian Soyuz spacecraft carrying two Soviet cosmonauts. The Apollo-Soyuz Test Project (ASTP) planted the seeds for a decades-long partnership in space between the United States and Russia, culminating in the International Space Station, where US and Russian crews still work together despite a collapse in relations back on Earth.