Everyone was happy last night in the caucus room of the Cannon House Office building except the guests of honor.

"It is something that has to be gone through," said astronaut Edwin E. ("Buzz") Aldrin at the party warming up for today's massive celebration of the 10th anniversary of the Apollo 11 moon landing. "I wouldn't want to do it every day of the week."

"I'm celebrating by not giving interviews," said Michael Collins, who almost made it to the moon 10 years ago.

No negative comments were heard from Neil Armstrong, who did not show up.

"Where is Armstrong?" asked John M. Logsdon of George Washington University, the author of "The Decision to Go to the Moon." "If he can make money out of this by selling Chryslers, he ought to be here."

John Lent, president of the National Space Club which sponsored the party for some 300 guests, explained that Armstrong had just returned from Europe and had been only tentatively expected. He promised that Armstrong would be on hand for today's party.

Only slightly more vocal than the strong, silent astronauts was astronomer Carl Sagan, author of "The Dragons of Eden" and several books on extraterrestrial intelligence and other space-related subjects. Cornered by a fan primed with questions, Sagan was laconic. What did he think of the Time essay on the future of computers? "Haven't read it." How about space colonies to produce solar power? "Too expensive." How about an autograph? "Yes. Sorry to be in such a rush, but I have a plane to catch." And off into the night.

Congressmen were not very numerous at the party on their own territory - perhaps because many space enthusiasts are angry at congressional refusal to fund the kind of programs the Space Club would like to see. One congressman present was Rep. Wes Watkins (D-Okla.), a rocket booster on the House Committee on Science and Technology. In 1969, the year of the lunar landing, Watkins recalled that "I was developing land in Wilburton, Okla., population 2,000." Where-were-you-when-they-landed was a popular question.

Other cocktail chitchat shied away from the usual Washington topics and focused heavily on space shuttles, laser beams, satellites and space trivia. "Have you tasted the space ice cream at the Air and Space Museum?" asked one fan. "It's dehydrated, but it tastes just like ice cream."

The Space Club, dedicated to promoting American preeminence in space, is open to anyone willing to pay $15 dues, but last night's party seemed heavily populated by executives from aerospace industries.

"I keep telling congressmen that everyone in this country under 40 is a space nut," one executive remarked. Looking around the room, one got the impression that a lot of people over 40 are, too.

Earlier in the day, a different atmosphere pervaded a luncheon for the men who had masterminded the;moon shot in its planning and perilous journey through Congress and bureaucracy.

They were hardly the Beatles, but to another generation of Americans they were heroes of a different sort.

Around the table sat James E. Webb, Theodore Sorensen, Edward Welsh, Olin E. Teague, T. Keith Glennan and Joseph F. Shea - men who helped put man on the moon.

Theirs was billed as a "hero's lunch" yesterday at the Library of Congress, a gathering of a dozen men who at one time or another figured prominently in John F. Kennedy's decision to beat the Russians in space.

The Librarian of Congress, Daniel Boorstin, called it "a conversation" as he led them into nostalgic recollections about Kennedy's mandate: man, moon, decade. Microphones recorded it all for history and another dozen or so guests listened with undisguised fascination.

"The most important feature of that decision was that it was an act solely of presidential leadership," said Sorensen, former adviser to Kennedy.

"There has been talk in recent days of a crisis of confidence in the United States," Corensen continued, "but then there was a crisis of confidence in the world."

Kennedy, he said, viewed a moon try as the kind of force needed to galvanize America, a goal similar to Columbus' dream of finding Asia.

"The president said, "Now space is the new sea and we must sail upon it"" Sorensen recalled.

John Kennedy's ghost, like Dwight Eisenhower's and Lyndon Johnson's, seemed to be a silent guest; few present neglected to mention one or all of the three.

T. Keith Glennan, the first NASA administrator (1958-61), said that while Dwight Eisenhower "was not a space cadet" he was a person with whom one could discuss goals for the future. Glennan laughed a little.

""Keith,"" he remembered Eisenhower saying, ""the moon's been there for many, many years. Whether we get there in 20 years or not makes no difference.""

The dozen men who sat in the cool, unhurried calm of the Library of Congress had changed considerably from the frenzied days when they played critical roles in the moon shot. One has had two strokes and his hands shake. Another has had open heart surgery. A third saw a psychiatrist for 10 years.

That was Joseph F. Shea, former NASA deputy director for the manned space flight and, by his and others' definition, "scapegoat" for the 1967 fire that killed three astronauts.

He spoke about that fire yesterday and his hands, too, shook. The Apollo fire was "the toughest" part of the program, he said.

Now a senior vice president of Raytheon Co., Shea said yesterday was the first time he had been invited to a space-related occasion since the fire. Several of the others, among the 30 guests Boorstin invited, had not seen each other in more than a decade.

And so for Olin Teague, former chairman of the House Committee on Science and Technology whom old colleagues affectionately called "Tiger," it was a chance to trade stories.

At lunch, Teague told of the elaborate lobbying effort he and others undertook in Congress to push the space program.

They also flew congressional skeptics to Canaveral and usually brought home converts. In the beginning he was a skeptic himself.

"I just didn't believe we could do it but I didn't have enough intelligence to keep my mouth shut."

Jim Webb, Kennedy's choice to head NASA, said he had had doubts without assurances of strong backing from the president.

"Unless we had complete support from the White House, McNamara and I would have been like foxes running in front of two packs of hounds, Congress and the press."

Webb's counterpart today at NASA, Robert Frosch, interrupted the recollections to add a few impressions of his own on how NASA decisions used to be made.

"I don't hear a long list of cost benefit analyses. I don't hear a description of a large staff effort where everybody in the world has to be involved, where everybody has to know what it's going to cost," said Frosch.

Shea agreed.

"If NASA had run itself as the Pentagon runs today we never would have done it." he said. "We'd still be arguing about going to the moon" had there been the clarity of purpose and definition.

Morie than any of the others, perhaps, Shea seemed to be reliving the exciting years that led up to the space shot. He described the late Wernher von Braun's efforts, imitating his German accent to the delight of his listeners.

And he told about rereading Greek mythology "because Apollo was a Greed god."

"I always felt," he said, "astronauts were better heroes than the Beatles for the kids."