Out of This World : MARS <i> By Ben Bova (Bantam Books; $20; 502 pp.) </i>

Camus said that the scientist, trying to describe the world, always resorts at last to poetry.

Many of us recall the majesty and excitement of mankind’s first forays into space exploration, when radios stayed tuned day and night to the proceedings; momentous events, grand discoveries, seemed just around every corner. Some of us, too, had already dreamed those first forays again and again, alone in our rooms in the company of writers such as Robert Heinlein and Murray Leinster. We felt redeemed.

But then somehow it all got too familiar. No grand discoveries were forthcoming, it was all terribly expensive and there really wasn’t much spectacle to it, and we had wars and that sort of thing to take care of down here, practical things.

In “Mars,” Ben Bova re-creates for us much of that first excitement we felt in reading about the possibilities of space flight or, later, witnessing the earliest manned exploration. A great international cooperative venture has delivered mankind for the first (and quite likely last) time to its neighboring planet. Each of those who debark--a Russian cosmonaut, an American astronaut, scientists from Brazil and Israel, a British physician--declaims a brief homily to mankind and his or her own nation. The last to speak, aboard more or less by chance, is Jamie Waterman, geologist and half Navajo. As he stands there--”a red man on the red planet”--what comes to him, pushing aside the memorized speech, is an ancient greeting: Ya’aa’tey.

The explorers’ agenda is specific. They’ve been brought to Mars as quickly and cheaply as possible, as a matter of political expediency: “The first Hispanic to serve as President and the first woman to be Vice-President, the duo had inherited from the previous Administration a Mars program that they would have canceled, except that it had gone too far to stop. Instead, they worked to win for themselves the credit for the first human landings on Mars while cutting expenditures for the program back to the bone. As political cynicism goes, theirs was almost trivial.”

And so the crew’s goal is not only to make this mission a success but also, if at all possible, to lay groundwork, provide reasons for future expeditions--to justify the ways of Mars to man, so to speak. Or at least to the politicians who decide things.

Not too surprisingly, Jamie turns out to be something of a hero and becomes a kind of spiritual leader to the other explorers. And when all are felled by mysterious illness--in a wonderful piece of want-of-a-nail plotting on Bova’s part--it is Jamie whose intercession, almost to the point of his own death, saves them.

But at a deeper level, it is Jamie also who provides the poetry. Here is Mars:

“The badlands grew much more rugged, until they were threading through a jagged stony forest of rock spires that loomed high above them; rock pillars carved into eerie sculptures that reminded Jamie of wildly abstract totem poles. The wind’s eroded away the soft stone and left these pillars of granitic stuff standing, he told himself. Then he realized that the gentle winds of Mars had to work for hundreds of millions of years to carve their magic this way.

“For hours they drove through the towering spires of stone. Jamie sat fascinated, staring, waiting to see symbols of eagles or bears scratched into the rock.”

Anyone familiar with Ben Bova’s work will know that everything in this book--information on the geology and climate of Mars, space technology from principles down to simple mechanics--is as rigorously accurate as possible. One senses right away that here is a writer to be trusted. The political intrigues he presents are convincing ones, and his characters, while they may wobble a bit off true, are for the most part believable human beings, truly created rather than simply plot-derived. But again and again, it is Jamie’s poetry that rings truest, that restores our wonder and guarantees our participation.

This is an expansive, almost encyclopedic work, beginning with the Mars landing and thereafter shuttling freely in time and place: back to crew selection and training, forward again to the workaday, breaths-held exploration, sideways to Jamie’s family and personal history, and to reactions and decision-making in power centers. There is rarely a false step; Bova holds our interest as surely with Jamie’s quiet visit to his grandfather in Santa Fe as he does in describing exactly how one gets into a spacesuit or in detailing the ruthless, rebounding self-preservation of political figures.

The explorers’ quest becomes a collective search for life, and one of the finest moments occurs when they come across a patch of green on a rock--which turns out to be merely copper oxide:

“Were you alive once? Jamie asked the world on which he stood. Will we find the spirits of your dead in the canyon? Are we the first to cross the gulf between us, or did your ancestors reach our world eons ago? Am I returning home?

“The softly keening wind gave Jamie no answer. The spirits of Mars, if there were any, kept their secrets to themselves.”

On Mars’ blasted landscape, beleaguered now by mankind’s social disorders, Jamie comes to an urgent realization. As Emerson said: “Wherever we go, whatever we do, self is the sole object we study and learn.” The world--this world or another, any world--will not give up its secrets, only its details. And in its landscape, finally, we can see only the aspect of our own faces. Bova hopes, as do we all, that like Jamie we can come to change, accept and finally admire what we see.