Skylab missed Washington, D.C., last week. But yesterday, the Carter Cabinet fell out of orbit 18 months ahead of schedule, breaking up into red-hot chunks of flaming political ego and scattering debris across the bureaucratic landscape.

Unlike the Australian ranchers who witnessed the spectacular descent of Skylab, Washington officials reported no panic among the herds of tourists and workers.

But in a town which can talk itself into a tizzy about the ouster of a deputy director of the General Services Administration, yesterday's shake-up involving five Cabinet-level officals was the biggest sensation since the "Saturday night massacre" of 1973.

Reactions varied from consternation to confusion, but the most widespread response was total disbelief.

"If somebody told me that Anastasio Somoza has just been named to replace Harold Brown as secretary of defense," Rep. Guy Vander Jagt (R-Mich.) said to a colleague on the House floor in eary afternoon, "I'd run out to see if it was on the news ticker in the lobby."

That was at a time when the only hard news was the ouster of Joseph A. Califano Jr., at Health, Education and Welfare and his replacement by Patricia R. Harris, until yesterday secretary of housing and urban development.

A few hours later, when Griffin B. Bell had been replaced by his deputy, Benjamin Civiletti, at the Justice Department and W. Michael Blumenthal was ousted at Treasury in favor of Federal Reserve Board Chairman G. William Miller, a lawyer who has worked in Washington since the early New Deal called a reporter to ask: "Have the monkeys taken over the zoo?"

There probably was some work done in some departments yesterday, but the crowds around the water coolers were 18-deep at times as bureaucrats exchanged the latest news flashes and rumors.

In the White House newsroom, bemused reporters vied in the black humor category in the brief pauses between the announcements of official executions by press secretary Jody Powell.

The author of this chaos - the president - was perhaps the most serene person in the city. His first public appearance of the day was a Rose Garden reception for the state presidents of the Future Farmers of America.Perhaps anticipating the upheaval he was about to launch, he said, reflectively, "So many changes take place...[but] the fundamentals don't change - love within a family, honesty, friendship among people, a desire for peace, a respect for one another...."

But there was precious little love and a surplus of disrespect for the White House among some of the officials in departments whose heads were lopped off in yesterday's executions.

HEW officials, watching Califano's farewell news conference on TV monitors in the lobby of their building, were muttering curses at Hamilton Jordan, the White House chief of staff and presumed architect of the shakeup. "I just LOVE being judged by the SOB who doesn't even pay his parking ticket," one of them said loud enough for a passing reporter to hear.

The evaluation forms dispatched by Jordan earlier this week to the department and agency officials were the targets of instant parody. The House Democratic Study Group invited its members to rate the White House staff on a scale ranging from "unfortunate" to "the best and the brightest."

Freshman House Republicans filled in an evaluation form for President Carter, praising his "good teeth" but deducting points for his habit of arriving at work "too early" and leaving "too late."

For those who walked the plank, the essence of the game was to exit smiling. Asked at his news conference if he was "mad" about being fired, Califano replied by quoting Carter quoting John Kennedy. "Someone," he said, "once said that life is unfair."

Blumenthal, who only Wednesday signed a lease for a penthouse apartment at Watergate, was asked, "Did you jump or were you pushed?"

"I took advantage of the opportunity to get parole," he replied.

To say that the upheavel caused nervousness among those who had momentarily survived was to understate the case.

Even the unflappable Robert S. Strauss, when asked about his plans, said, "I expect to serve as trade representative for a rather extended period of time - perhaps until next week."

Republicans had a field day as spectators at the Democratic circus. House Minority Whip Bob Michel (R-III.) compared Carter to a "schoolmarm trying desperately to bring the class to order, with spitballs and paper airplanes flying around his head. He doesn't know it yet," Michel said, "but school's out."

There were jokes among the Democrats, too, but they were a thin veneer on the anger many of them expressed at the firings of Califano and Blumenthal, regarded by many on Capitol Hill as among the ablest of Carter's original Cabinet.

The feeling was that the firings had - in defiance of ballistic laws - done more damage to the executioner than to the victims. In the House Democratic cloakroom, this joke spread: "What do you do when Jimmy Carter comes at you with a pin?"

"You run like hell. He's got a grenade in his mouth."