HE'S known as "Moonrock" on the Hill, at least by the irreverent young majority committee staffers. When the starts talking, they roll their eyes up to the hearing room ceiling, push their papers around, whisper among themselves behind the backs of their hands. They snicker. Moonrock again. Another tedious, predictable diatribe on "regulatory overkill." Or some far-out scientific input lifted from the high-tech halls of NASA that nobody even wants to understand.

Moonrock rasps on. He doesn't even know he's being laughed at, they figure. He's spaced out in his impenetrable ormolu control module.

Majority leader Robert Byrd (D-W.Va.), the quintessential image of a senator, natty in a slightly flared three-piece, beige poplin suit, gray hair sweeping in perfect vectors from high forehead to trimmed nape, faces Moonrock across the wool-carpeted Senate floor. This is a study in contrasts. Tall, mellifluous, graceful, veteran Eastern Democrat versus short, harsh, blocky, inexperienced Western Republican.

The Western Republican, junior senator from New Mexico and former astronaut, a.k.a. Moonrock, is one Harrison Hagan Schmitt. The issue is energy. Part of the president's stalled energy bill has finally reached the floor. The president himself is at the Bonn economic summit and Byrd is trying to drum up a favorable vote for him . . . at least on this small item, which would give the government some regulatory control in the conversion of the country's power plants from oil to coal.

Moonrock isn't having any of it. He says the bill is "regulatory nightmare." He declares he is out to head off the vote, at least until he has had time to study the conference committee report and ask some questions. Being a scientist and something of an energy expert, he has lots of questions. By the time they are answered, incidentally, the vote would come too late to help the president.

Moonrock is all alone, standing way back in the farthest reaches of the Republican side, the least senior, least powerful position in the whole chamber, where noise from the tourists seeps through the cracks and hurrying pages occasionally knock his notes to the floor. He stands short, squat and dark, with his head down and his shoulders squared. His voice marches from one point to the next, with an agressive lift at the end of each paragraph. His clothes are square-cut. Only his gestures seem out of character: his hands move lighlty, precisely and on time, in and around the words, like an orchestra conductor's.

"The bill has as its underlying assumption that Americans want more regulation. Well, as I said earlier, I do not think Americans want more regulation. They certainly do not in New Mexico, and I have not seen it anywhere else I have been in this country, and I do try to travel around a bit. Americans want less regulation. For one thing, they are tired of being told what to do in every facet of their lives. They want to try again to do it themselves, as we used to . . ."

The Democratic senators - Haskell, Ford, Jackson - stand in a little cluster around Byrd. They act as if they have heard this song before. Byrd draws himself up to his full senatorial height and authority, graceful but dour and deadly serious, with the weight of years of successful cloakroom politicking behind him. He delivers a full-armed blow toward the desk in front of him, which ends in a light tap, perfectly stylized. He pricks - "This idea of one senator being able to hold up the Senate and conduct a one-man filibuster is getting to be pretty rife around here."

Byrd challenges - "If he wants to hold up a bill, if he wants to speak tonight, if he wants to speak Saturday, if he wants to speak Sunday, that is within his right. I will tell him right now he has a taker. He has one right here who will take him on." And then he capitulates. All right. The vote will be delayed over the weekend until Tuesday, while Moonrock has his questions answered.

The answers, of course, turn out to be perfunctory, almost a rote exercise. The Tuesday vote is 92 in favor of the bill, Moonrock and five others against it. The fact that the president left Bonn without it is not mentioned in any news accounts, which hail the summit as generally successful.

It is tiny victory. Nobody but Moonrock would have bothered with it. But Moonrock, 95th in seniority and the president's most stubborn opponent in the Senate, not only bothered with it but actually expected his questions to be answered seriously.

Sen. Harrison ("Jack") Schmitt, the 43-year-old freshman senator from New Mexico, has a Harvard doctorate in geology and was the last man to set foot on the moon. His Moonrock nickname also has something to do with the fact that he has earned a reputation among his detractors for being abrasive as pumice, uncompromising as granite, technologically abstruse to the point of being otherworldly. And, they have to admit, representing a new, unknown, and slightly unsettling element.

Ten, maybe even five years ago, Schmitt probably would have been discounted as an aberration by more than just the irreverent young majority committee staffers. But things are changing under the crystal chandeliers and within the walnut paneling of the country's "most exclusive club." Members are getting younger, more outspoken, and more conservative. And less like conventional politicians all the time. So people don't automatically discount Schmitt in the new Senate. They observe him with a certain bemusement, they scratch their heads and they allow that he has "potential." Who knows? He has collected degrees, fellowships and honors as if they were seashells, comes on enthusiastic and as incorruptible as an Eagle Scout.He's willing to talk for three days to make a minor point.He doesn't seem to understand about the way a senator should operate, or even seem to care a whole lot. (Over a light lunch in the Senate dining room recently, Schmitt observed: "You know why they stopped serving wine here 10 years ago? Because a lot of senators were getting too drunk to vote. Didn't slow them down much though. Sixteen months ago there were still a lot of drunk senators on the floor.") But the way things are going these days, being the Senate's most politically naive enfant terrible could in the end turn out to be a plus.

Of course there are other unconventional young Western conservatives in the new Senate - Utah's Orrin Hatch and Jake Garn, Wyoming's Malcolm Wallop, Idaho's James McClure, New Mexico's Pete Domenici - and if you can believe the polls, there will be more. They call themselves "progressive Republicans" and claim to have new approaches to old conservative goals. They are down on big business. There isn't much big business in their states anyway. They'll mix easily with conservative or even maverick Democrats like Daniel Patrick Moynihan (D.-N.Y.) Schmitt votes with them on most issues and tends to be lumped with them under the heading of "New Artillery on the Right," or the "cactus conservatives." He helped them torpedo the labor law reform bill and the Panama Canal treaty. However, he so far hasn't joined any conservative groups ("I am not a joiner") and has voted against such interests on issues like aid to New York City and abortion.

Schmitt stands out another way, too. With the possible exception of his friend, semanticist S. I. Hayakawa (R.-Calif.), he seems the most unlikely politician of them all. "When I heard he decided to run, my first reaction was 'What has the boy been smoking?'" a friend from NASA says now. "I advised him against it because he was from a different world," another remembers. Others think of him as "guileless," "hypercritical," lacking in "social instincts" and "worldliness." Depending on whom you talk to, Schmitt was either the most unpopular astronaut among his colleagues, or "one of the least popular." His conversation is a mixture of technology, homily, bad puns, putdowns, methodical, almsot academic argument, and boyish optimism . . . unlike any politician you've ever heard. However, he did get to the moon - the only scientist ever to do so. And he did carry the state of New Mexico in an upset victory by 57 percent of the vote.

"It makes me feel secure to know we have a man like Jack in the Senate," is one thing you hear a lot from his former scientific colleagues, no matter what their politics. Almost as often: "If I had to be marooned on a desert island with somebody, I'd pick Jack. He's a survivor." Taken together, the two statements have an air of crisis about them, as if in some kind of political translation Americans are about to be marooned indeed.

Part of the new conservatism could come from such a man. No more softhearted nonsense. The tendency is back to basics, which in this country has always meant the basic issues of the frontier. The hero of the new conservatism will be someone who can keep us alive, protect us from the Indians, and let us get our goddamn crops in without interference. Such a man won't be a frock-coat politician, which is something nobody ever accused Jack Schmitt of being. And it might not even be a particularly mellow guy. Schmitt, for example, is enough of a workaholic that he hasn't found the time to put a lamp in the living room of his Capitol Hill row house, which he has owned since 1974.

His friends say he doesn't have time to get married. "Jack has almsot purposefully overshadowed his personal side," a former girl friend says. "He is most comfortable in a work environment."

Schmitt has a certain quality that t'ai ch'i enthusiasts call "centeredness." He would be a hard man to physically push over, or grab hold of and throw down. If you got in his way, he'd roll over you like a bowling ball. In t'ai ch'i, this quality emanates from being psychically centered rather than physically.

Which brings to mind another thing his friends from astronaut days keep saying: Jack is "unflappable." Everyone in the Apollo program was haunted by the deaths of Gus Grissom, Ed White and Roger Chaffee when fire in the cockpit of Apollo 1 burned them up in less than 16 seconds during a routine launch-pad checkup. Jack Schmitt is remembered as the man who took a two-hour nap during a launch pad malfunction before takeoff while his crew leader, Gene Cernan, kept his finger on the ejector button.

On the other hand, Schmitt, who with his light, precise movements was far and away the best scientist -pilot in the program, never flew again after returning from the moon. As with the rest of the scientist astronauts (a distinctly separate subgroup as opposed to the jet jockeys), flying was never Schmitt's prime interest anyway, but it was a critical skill he had to develop to get to the moon. Rather than use a light plane, he drove a pickup truck while campaigning in New Mexico. And he won't fly private planes to lectures even now without a complete rundown on both the plane and the pilot. Centeredness, apparently, comes from dealing methodically with the odds down to the last micrometer of possibility and then not worrying about them anymore.

Jack Schmitt has his glasses off. Chromeplated aviator style, the lenses seemed shadowed on the top a la Yves St. Laurent. They were a discord . . . just not going with a can-do technologist from the frontier. Now that he has them off, though, it is apparent it wasn't his glasses that produced the effect, but his incredibly deep eyesockets, thick eyebrows and black eyes. His skin is dark, his nose is arched, his hair is thick and black and low over his forehead. He likes to speculate about there being a Cherokee in his family (more than seven percent of his constituents are Indian), but he doesn't know for sure.

In a hearing room now, after leaving the Senate floor, he has taken off his glasses so as to seem closer to about 75 of his staffers and friends. As a special treat, he is showing them his moon slides. There is an air of innocence and inexperience about the people in the room that nicely complements Schmitt's.The girls wear lots of chiffon, long wide skirts and have natural shoulder length hair. They outnumber the men about two to one. The men are earnest, unbearded, shorthaired. There is one black, a woman. They seem to represent the Republican heartland.

Schmitt's slightly sensual Richard Burton grin does not match his methodical words: "The question of what was it like on the moon breaks down into three parts: What did it feel like? What did it look like? What were the emotions?" One is not surprised to learn that Schmitt has an absolute reverence for technology . . . technology that is possible only in a "free society." The saddest moment of the flight for him was when they jettisoned the lunar module. He'd become attached to it.

An emotional aspect of the flight was romantic, surprisingly enough . . . almost Kennedyesque: "When it actually occurred, when you actually got there, even though you'd thought about it and studied it for years, it was much more than you could possibly anticipate. Why? Because you were there, you were actually on the scene. That's why I'm confident that men and women in the future, particularly Americans, are not going to be satisfied with just pictures. They are going to want to go there. Then after a while somebody up there will say . . . 'We're tired of taxation without representation,' and Jefferson's little revolution will happen. The cycle will start all over again."

In fact, when he spoke to the House about his moon experience back in 1973 while he was still with NASA, Schmitt even sounded a bit like the ripe, romantic Rachmaninoff, his favorite composer: "The Valley of Taurus-Littrow is confined by one of the most majestic panoramas within the view and experience of mankind. The roll of dark hills across the valley floor blends with bright slopes that sweep evenly upward, tracked like snow, to the rocky tops of the massifs. The valley does not have the jagged youthful majesty of the Himalayas, or of the valleys of our Rockies, or of the glacially symmetrical fjords of the north countries, or even of the now intriguing rifts of Mars.

"Rather, it has the subdued and ancient majesty of a valley whose origins appear as one with the sun."

He wrote a poem about it, which he refuses to make public. He wrote another about his dead father, others about love affairs. He has named craters on the moon after the Bronte sisters, C.S. Forester's Horatio Hornblower, and Pasternak's heroine Lara in Dr. Zhivago. He commissioned a huge orange (his favorite color) impressionistic painting for his dining room that looks like a blob of pure emotion. His heroes include Churchill, Lindbergh, John Kennedy, and one Lt. William Emory, a pre-Civil war topographer who mapped much of the Southwest. He is friends with Moynihan, who has complained it bothers him to be voting so often against "a man like Jack Schmitt." (One reason for their friendship, some people say, is that they are the two brightest men in the Senate, and they are both intellectual snobs.)

Schmitt grew up in Silver City, N.M., home of Pat Garrett, where Billy the Kid gunned down his first man.

Schmitt was forged and tempered in his white hot relationship with his father, an ex-Marine whose politics were Reaganesque and who gave off a classic frontier flavor, tinged with technology. They'd go prospecting together, and when he finally got to the moon four years after his father died of a heart attack, Schmitt took a little bag of copper ore along in memoriam. This summer Schmitt took his first vacation since his 1976 election and spent two weeks refurbishing a cabin he and his father had built on an island in Minnesota. Between them was the attraction and the repulsion of sameness, which is probably why Schmitt now delights and thrives in the adversary position. Schmitt senior, watching the Depression and the Roosevelt era from Silver City (pop.13,000), was certain his beloved free enterprise system was going down the tubes. So, during his Harvard days in the early 1960s, Schmitt junior vowed to go into politics someday to prove his father wrong. Simple as that. Not that they disagreed on the ends: "A maximum of individual opportunity with a minimum of government interference and a strong defense."

In the meantime Schmitt followed his father's footsteps into geology, not exactly a political training ground but requiring (he argues) the same combination of intuition, command of facts and "good common sense."

Competition with father was intense enough to convince the only son (there are two daughters) that "the competitive drive is the strongest biological force in the world," and Schmitt has based his life on it. "If you can channel that drive, it can do anything. It should never be interfered with. The free market should be pure competition. There's nobody smart enough to regulate it."

Schmitt is fond of comparing competition among astronauts to competition among senators, to the point of trying to use the same technique on the Hill that got him, instead of other scientists, to the moon.

It was oneupmanship, a variation of the "two-club ploy." If your two clubs, say, are an athletic club and a literary club, you always talk athletics among the writers and writing among the athletes. Properly done, everybody is kept off balance . . . and you come out on top.

At NASA, the two clubs were the scientist-astronauts, who had to learn to fly in order to be selected for a moon voyage, and the test pilot-astronauts, who had to learn science. Flying had always been the elite skill . . . until Schmitt came along. The crewmen had always been pilots. But the science lobby was getting stronger. Sooner or later a scientist was going to get to go, and Schmitt put himself in the forefront by becoming the best pilot among them.

He could hardly compete with the jet jockeys in flying, but he was in charge of teaching them lunar geology techniques. And in that field, the aces were ignorant children. They had to learn from him.

The two club ploy.

"There was unbelievable friction between him and the pilots," remembers Apollo geologist Farouk E1-Baz. "In retrospect, Jack's primary contribution was not so much his own scientific ability as it was the way in which he made the whole crew compete with him. They did not want that little guy to be a hotshot. They were going to break their necks trying to learn as much geology as he already knew."

Meanwhile Schmitt put in yeoman duty in the flight simulator, developing superior flying skills in comparison to the other scientists. "I wanted to make it impossible for them not to select me," Schmitt says. And he did.

Slightly less than four years after he returned to Earth Dec. 19, 1972, Schmitt set out to make it impossible for the voters of New Mexico not to elect him senator over Democratic imcumbent Joseph M. Montoya.It wasn't too hard. Montoya's personal finances were under fire, and if there is one thing Schmitt can project even more strongly than competitiveness, it is honesty . . . "Honesty for a Change."

The campaign revealed two apparent inconsistencies about Schmitt. First, as a man used to expertise and being surrounded by experts, he hired nothing but the rankest amateurs for his campaign staff. (His manager was the 28-year-old wife of an Air Force colonel he'd met through the space program.) Second, as a man used to the exclusive professional company of men in the space program, he surrounded himself with six women for every man in the campaign organization.

But the explanations are pure Schmitt. He is something of an intellectual snob. Politics is not a science in the strict sense, he figured, therefore, there can be no political experts. He likes to tell former scientific colleagues that they are brighter than the average politician, and if they were to turn their brains to it, they too could get elected.

As to the women, according to a former aide and girl friend who is no longer on his staff: "He's seen what competition and rivalry can do to a staff, and he perceives women as being less agressive, willing to work harder for somebody else, with less back-talk. It takes him a while to trust people, and he has always trusted women more than men."

Schmitt says, "Men tend to sit around and talk, women to be active and do things. There are practically no unanswered phone calls on their desks, for example." Many of these same women are still with him, on his office staff, where they continue to hold key positions and outnumber the men three to one. The Air Force colonel's wife is now his administrative assistant.

Geologist-astronaut-politician. Some Schmitt watchers have compared his career to a three-stage rocket, each stage making its contribution to the flight and then dropping off. Schmitt sees himself as a flow chart in which "all the possibilities are maximized." He didn't become a geologist so he could become an astronaut, or an astronaut so he could become a politician, he says. On the other hand, his first geology job out of Harvard was with the U.S. Geological Survey's Astrogeology center in Arizona, where he was project chief for lunar field geological methods. And he began setting campaign savings aside almost as soon as he was selected to begin training as an astronaut. That might be called good programming.

So Schmitt went to Washington claiming that politicians are lawyers who tend to think in terms of symptoms rather than solutions, as scientists do. "My top personal priority is the process of imposing a new set of considerations from my background and experience that have not yet been part of deliberations around here," he says grandly.He is operating under the assumption that diligence, intelligence, discipline, commitment, irrepressibility and solid science will be recognized here as they were in the space program.

The two-club ploy. He comes on like a scientist in a chamber of political jet jockeys.

he trouble is, unlike the astronauts, politicos are under no compunction to listen.If they want to know about science, they can talk to experts of their own. They don't need to get it from the junior minority senator from New Mexico. They laughed at him when, after a few months in office, he introduced an ambitious, compendious energy program, a digest of everything he'd learned at NASA . . . on the floor. And expected them to take it seriously. Why, he wasn't even on the Energy Committee, which is where, according to tradition, such things should originate.

Schmitt's committee assignments, the best indicator of Senate status, are only so-so - Banking, Housing. Urban Affairs, Commerce, Science, and Transportation (where he is ranking minority member of the subcommittee on Science, Technology and Space). He also serves as vice chairman of the Ethics Committee, a clear reflection of his days with the astronauts, when he used to complain about the ethics of astronauts selling their stories to Time magazine and accepting free Corvettes from a local car dealer. No Corvette for Schmitt. He drove a secondhand VW. "He accepted Ethics because whole governmental system," says a former aide.

"But he regrets it now. He really didn't need any more Boy Scout stuff tacked onto him."

Schmitt was too much of a maverick for one of the "big five": Appropriations, Armed Services, Foreign Affairs, Budget, and Finance. And Pete Domenici, his senior colleague from New Mexico, was already on Energy.

So where does that leave Schmitt? Basically taking potshots from the floor and being something of a professional bull in a china shop. "He believes that priorities can be reordered, and that we can get back on the right track, but he lacks the understanding about what is needed to accomplish that," one committee staffer says.

"I'd rate him A for hard work and integrity, C for accomplishment," a Senate colleague allowed. "He simply hasn't bothered to learn that in the Senate one man can't do everything. He's so positive he's right, he can't understand why others won't go along. Maybe he'll never be able to."

In some respects, senators have traditionally been more like countries than people. They are buffered from each other by huge staffs, mammoth egos, political considerations, even by style and image. Schmitt sees himself as the viper in the bosom of all that. He'd like to see less of everything, including legislation itself. He has introduced relatively little. (Other than his energy resolution, he points to his proposed Regulatory Reduction and Congressional Control Act; which would require any federal rule submitted to Congress to be accompanied by economic, clerical and judicial impact analyses, and which has yet to get a hearing.) He refers to his worthy opponent on the president's coal conversion bill, Majority Leader Robert Byrd, as a "technician" who has based his career on the mechanics of pushing bills through, and not much else.

Ironically, Schmitt is yoked on many of his committees and subcommittees with Sen. Adlai Stevenson III (D-Ill.), the quintessential liberal Democrat. Even more ironically, they seem to get along.

"The Senate is changing," Stevenson says, "One of the ways for a freshman to fit in was to keep quiet. That's breaking down, though, and nowhere more so than in the case of Sen. Schmitt. He's loquacious, at times unfortunately loquacious. There is definitely a feeling that he's pushing too hard. But he's a pleasure to work with because he's completely without any guile. He's scientist who believes the straightest distance between two points is a straight line. That's a hard commodity to find."