On a run either in the morning or the evening, I forget which, but plugged in via my Walkman to National Public Radio, I heard a commentator, Tom Noyes, talk about Pioneer 10. After ll years in space, it is embarked on a journey beyond the solar system and, given no obstacles and several billion years, may get to the edge of the universe--the edge of the universe!--which is the sort of possibility that makes you slow your pace and think, as Noyes has done, about what we human beings have quite by accident achieved--immortality.

Noyes must be a child at heart, the sort of person who still thinks about the imponderables, because he brushed right past the technical hocus-pocus and went straight to the meaning of it all. That is precisely the sort of thing the well-scrubbed space program obscures, but, of course, it was there all the time. Immortality. That is what we are after.

It is almost a shame that Pioneer had to pick this time to glide silently and frictionlessly past Neptune and then hurtle on its way to infinity. The attention of America was on its first woman astronaut, on what can no longer be called the "manned" space program, but compared to Pioneer and its mission, the space shuttle seemed so prosaic. Pioneer, after all, was already 2.8 billion miles from Earth when it passed Neptune on the fly, heading out of the solar system for its first encounter with a star 10,507 years from now.

And then it will just keep on going. Space is so vast, the chances of Pioneer hitting anything so small, that it is possible to chart its course for 800,000 years and estimate that its shortest lifespan will be two billion years. But even that is nothing and Pioneer can go on and on. It has affixed to it a plaque with the images of a man and woman and a sort of solar system map, showing where Earth is. When and if someone comes across it, though, man may no longer look like man or woman like woman and Earth, given enough Andropovs, Reagans and the MXs both sides have, may be long gone.

But not Pioneer. Like Superman put into a rocket moments before the destruction of Krypton, it will survive whatever we do to one another and whatever becomes of our planet. It is nothing less than the latest in a succession of attempts at immortality--like the pyramids, like religion and its promise of afterlife, like, I suppose, poetry and music and pathetic proclamations of eternity expressed in terms of a thousand years. A thousand years? We are talking of billions of years. A 570-pound hunk of aluminum mocks our petty concerns.

The late Harry Golden, publisher of the Carolina Israelite and author of "Only In America," once wrote an essay along those lines. He wrote of the stars, of the vast number of them and the distances between them. He wrote of galaxies known and galaxies imagined and then, after he had written of numbers incomprehensible and distances unimaginable, he asked how it was possible to bawl out the waitress for bringing green beans instead of green peas.

This is the feeling I had when I listened to Noyes on the radio. In the context of the space program, it was a new feeling, because I have always thought of the program as bland and space as just another government reservation where you have to wear your hair short.

But Pioneer brought me back to the days when I was a boy, when my friends and I used to go out to the weeds at night and look up at the stars and wonder as hard as we could what was meant by nothing . . . and infinity . . . and whether there was a God and if so (and no offense, Sir) then how could He allow what had happened to happen--like, just for starters, the Holocaust.

But the voice of Noyes and the image of Pioneer reversed it all. Instead of looking up at the stars I was looking down at Earth, imagining the moment billions of years from now when someone comes across Pioneer, looks at the image of man and woman, wonders what has become of us and ponders a civilization that quite by accident achieved immortality--and, maybe, destroyed itself the same way. Fly on, Pioneer.

Tell 'em we were once here.