KIM Spencer could have had a walk-on role in a movie about the 1960s. With his tall frame topped by a not-quite-tamed head of curls, he looks like a veteran of antiwar and antinuclear protests - which he is.
Those mass movements gave him the improbable idea of using satellites to link groups of people in the United States and the Soviet Union to talk about avoiding nuclear war - to get impressions of each other as people, rather than ''the enemy.'' Maybe even to dance to each other's music, or sing each other's songs.
Fat chance. As if the language, communication, and distance barriers could be breached. As if the cost would be less than, well, astronomical. As if the Soviets would allow it.
So what's Kim Spencer doing in the pre-dawn hours of a snowy Moscow morning?
He's huddled with officials of the Soviet State Committee for Radio and Television (Gosteleradio) ironing out the final details of a satellite transmission between San Francisco and Moscow, during which participants will talk about avoiding nuclear war and sing songs.
It's the sixth such link that's taken place between the two superpowers in recent years, and Mr. Spencer, a producer with the Internews Project, has been involved, in one way or another, in most of them. Taken together, these ''satellite bridges,'' as they have been dubbed, represent a technical tour de force - and an example of a unique kind of cooperation that has endured stormy political relationships between the two countries.
To hear both Soviet and American enthusiasts tell it, what's been accomplished so far only hints at things to come. One Soviet producer says he'd like to see sports events beamed between the nations, with bilingual explanations of the rules and play-by-play.
Spencer is toying with an even more ambitious idea: a three-ring circus-by-satellite, with acts beamed simultaneously from Moscow, New York, and Peking.
To be sure, these ''bridges'' are more than entertainment. They are used for political purposes in both countries. They have provided opportunities for American scientists, entertainers, and issue groups to get an audience in Moscow. And Moscow gets to present a human face to the US that furthers its propaganda aims.
''I think,'' says Spencer, ''that the Soviets have a different view of what television is. It has to do with their view of propaganda, which we see as a totally pejorative concept. They see it as an opportunity to inform, to persuade. . . . They use it to try to depict the realities of the world, or at least the realities as they see them.''
A Gosteleradio producer voices similar sentiments.
''Space bridges,'' he says, do away with the ''prism'' of newspapers and commercial TV through which most Americans see the USSR. Satellite links ''promote a better understanding than (the) somewhat biased look at Soviet reality'' shown by commercial media, he says.
The Soviet Union does maintain a tight control on the images it allows to cross these ''space bridges.'' Participants in Moscow are carefully screened, and so far none of the satellite programs have been broadcast live here. Only taped and edited versions have been seen on Soviet TV.
Spencer says he has carefully reviewed the Soviet versions, trying to answer the question, ''Are we being used?''
''Basically,'' he says, ''they've gone out pretty much as they happened.''
Of course, the Soviets carefully pick and choose the programs in which they participate. But the idea behind every program so far has originated in the US.
The most recent ''satellite bridge'' seemed made for Moscow tastes. It was an awards ceremony sponsored by a San Francisco organization, ''Beyond War,'' which honored the International Physicians for the Prevention of Nuclear War.
A prominent Soviet Communist Party member, Dr. Evgeny Chazov, is co-founder and co-president of the group. Its message - that nuclear war must be avoided and nuclear arsenals reduced - has Moscow's fervent backing. (Critics would say it is for the purpose of swaying American public opinion toward unilateral arms reduction, while Moscow continues its own arms buildup.)
There may have been less to the award than met the eye. Both Dr. Chazov and his co-recipient were members of the selection committee that chose them as award winners. They could have accepted in one spot without satellite.
But perhaps a satellite link provides its own rationale. The technology becomes part of the event. For example, even a hardened cynic might have been moved by the sound and sight of a San Francisco boy's choir and a Gosteleradio children's choir singing together, though halfway around the world. Their electronic images arced through space, and reappeared as one on giant video screens in each city.
In a 1983 ''space bridge,'' the Moscow rock group Arsenal played songs that set crowds to dancing in the California desert near San Bernardino. Other ''bridges'' have been used to discuss the possibility of a ''nuclear winter'' as well as to facilitate a meeting of scientists for discussions of fusion and seismic research.
In the latest video-audio hookup, a signal from the Gosteleradio studios in the Moscow suburb of Ostakino went by phone lines to Dubna, north of the Soviet capital. From there, it was converted into a satellite signal, and beamed to an Intelsat satellite over the Atlantic. The signal came down in Etam, West Virginia, where it was sent via phone lines to New York. Then it was rebeamed to the Westar 5 satellite over the American Midwest, and then down to a portable satellite dish in a park across the street from San Francisco's Masonic auditorium. A final microwave link sent it across the street, to a van packed with electronic hardware, where the electronic images were blended into a 90 -minute program. This signal was then rebeamed to yet another satellite, which provided the program to number of public and cable TV stations. And yet another satellite signal retraced this route in reverse, from San Francisco to Moscow.
''Technically, they're very good,'' Spencer says of the Soviet satellite team.
''And once the decision has been made to do something, working with Soviet television is a delight. They're very professional.''