The project was the culmination of a scientific agreement signed three years earlier by President Nixon and Chairman of the Soviet Council of Ministers Alexei Kosygin.

Two crews -- American and Soviet -- were to dock in Earth orbit, shake hands and exchange gifts. The event was to be broadcast on television worldwide.

It would be the first time that Moscow had announced any of its launches in advance. It also would also be the first time a Soviet mission -- in this case Soyuz 19 -- would be broadcast live on Soviet television.

So the stage was set for the global meeting when Apollo commander Thomas Stafford called his favorite singer, Twitty, that March to ask a favor.

Stafford thought it would be a great idea to present cassettes of "Hello Darlin'" to the cosmonauts during the gift exchange. Would Twitty be willing to record his song in Russian?

At first Conway thought it was a joke, although he'd had experience in recording in foreign languages when he played rock n' roll.

"When I discovered it was for real, I immediately got busy. Fortunately I found Professor Gurij Chemelev at Oklahoma University to teach me enough Russian to get by," Twitty wrote in his autobiography.

Twitty, who died in 1993, tells the rest of the story in his book: "So he came down to the studio and he sat on a stool right there beside me. I thought it would take maybe an hour. But it took a long time.

"The professor would say 'No, no, no,' when I got the accent wrong. Having told me that the title translated into 'Privet Radost' in Russian, first problem was that I'd say the words softly and he would shout more 'no, nos' at me. We went around and around, and it took him forever to understand that you don't just holler 'Privet Radost' at a woman.

"'In Russia they do,' he replied.

"Anyway, I finally got it all finished and sent the tape to Stafford. A short time later I was out in L.A. doing a show, and I was back in the dressing room watching Walter Cronkite.

"On this particular day all the astronauts and cosmonauts were up there in the same space capsule. The camera was focusing on them, and out the window you could see the Earth spinning below. It was July 17, 1975."

"All of a sudden, the talking stopped and the song started playing: 'Privet Radost.' That song was played in Russian all around the world. I don't know how many millions of people heard it -- the only time anything like that had ever happened! It was a tremendous experience."

Though Twitty was impressed, he was wrong about the day. According to NASA's records, "Privet Radost" was broadcast not on July 17, but on July 19 at 10:25 p.m. Eastern Daylight Time (02:25 GMT).

By that time the famous handshake between Stafford and Soyuz commander Alexei Leonov, along with the formal exchange of gifts, were over. And the song aired just 52 minutes before the two spacecraft were to undock.

Still, the unusual broadcast prompted Mission Control in Houston to remark: "That sounded like it was from far Western Oklahoma -- around Kiev."

Stafford replied: "No, that was Conway Twitty in Russian for the Soyuz crew and the people in the control center."

The magic of the moment was fleeting, however.

The Soviets had long been deferring any plans for future joint missions and the hoped-for follow-up never occurred.

The next time that U.S. and Russian spacecraft would rendezvous would be 20 years later -- after the collapse of the U.S.S.R. -- during the STS 63 mission in February 1995. That's when Space Shuttle Discovery made its close approach to the Mir space station to kick off a new era in U.S.-Russian space cooperation.