In the late 1970s, when the Carter administration was pressed to send a private citizen into space early in the shuttle program, the National Aeronautics and Space Administration ruled that flights would be limited to individuals "whose duties are essential to mission services" until "the full orbiter fleet is operational," according to space agency documents.

The crew would be restricted to "the commander, the pilot, and mission and payload specialists," NASA Administrator Robert A. Frosch told Congress.

The Reagan administration changed that approach in a decision that was fateful for teacher Christa McAuliffe and that has led to weeks of recriminations and NASA soul-searching. In early 1982, the space agency set in motion its citizen-in-space program as the four test flights of the first shuttle Columbia were under way. McAuliffe thus was aboard the ill-fated shuttle Challenger two years before the shuttle fleet was to be considered fully operational by the administration's standards.

Although NASA announced two weeks after the Jan. 28 Challenger explosion, which killed all seven aboard, that civilians would continue to ride the shuttle, some members of Congress and outside experts want to look at the issue of putting private citizens into space while the shuttle program is still in its early stages.

John G. Stewart, a member of NASA's Aerospace Safety and Advisory Panel, said in an interview that he was "ashamed" the panel had not "raised questions earlier" about the citizen program, but said it would do so now.

And Sen. John Glenn (D-Ohio), a former astronaut, disputes the strategy of putting a "lay person in space for the purpose of gaining public support . . . while the shuttle is still in its embryonic stage," according to an aide. Glenn, however, wants the shuttle to carry scientists involved in basic research when seats are available.

A review of records and interviews with past and present NASA and government officials shows the civilian program's controversial background, with different groups pushing for different approaches.

On Feb. 25, 1984, President Reagan signed a National Security Decision Directive that said the shuttle system was not to become "fully operational" until 1988 or later -- when it was able to launch 24 missions a year. NASA's "1986 Long-Range Program Plan" last August listed as one remaining objective the "upgrading of the shuttle system to its full capability, and achieving routine operations with it by 1988."

NASA told its safety panel late last year that the shuttles continue "in the evolutionary process of becoming 'operational,' " a goal the panel concluded "remains sometime in the future."

To illustrate that, the safety panel said it found that after a shuttle returned to Earth and went into preparation for its next flight, almost half of the so-called "turnaround time" was used to make unplanned modifications, tests and "changeouts resulting from flight concerns and anomalies."

Despite these indications that the shuttle was essentially an experimental vehicle, Reagan's NASA administrator, James M. Beggs, began preparing as early as mid-1982 to put a citizen in space. He said the process should begin "as we approach the operational phase of our shuttle system," according to a letter to NASA's Advisory Council requesting a study on how to select private citizens to go into space.

When that study group first met, in July 1982, Beggs told the members that because mission and payload specialists were scheduled to begin flying later that year, "there is a growing, persistent demand to fly passengers at the same time there are a growing number of space flights which might provide opportunities."

Thus seats available on the shuttle, rather than the achievement of fully operational status for the space vehicle, became a prime reason for deciding when to send the first private citizen into space.

In an October 1982 five-year projection of flights, NASA supported the idea that more seats would be available in earlier than in later years.

NASA projected 12 launches in 1984, with seven that could take passengers; 14 launches in 1985, eight of which could carry passengers; 17 launches in 1986 of which six could take passengers; and at least 17 launches in 1987 with only two capable of taking passengers.

The declining availability of passenger seats was caused by an increase in proposed military flights, which barred the presence of anyone not associated with the mission.

The chairman of the 1982 panel on the selection process was Dr. John Naugle, a retired NASA official who then worked for Fairchild Corp. Naugle said in an interview that his group did not make any judgment on when NASA should fly a civilian. "We left open when NASA would feel comfortable flying passengers," he said, adding it might be "20, 40 or 80 launches before the agency flew a citizen."

Naugle's group traveled to the Johnson Space Center in Houston, where members were presented with NASA's optimistic five-year flight plan. Faced with that schedule, the Naugle panel eventually suggested that "the flight of three to four passengers in the mid-to-late 1980s was a reasonable number to use for our considerations."

In fact, NASA launched only five shuttles in 1984 and eight the next year. Thus last Jan. 28, when Challenger was launched, it was only the 25th mission for the shuttle program. Under the plans shown to the selection panel in 1982, that date would have marked the launch of the 37th mission.

While the shuttle flight program fell behind its projected schedule, however, the citizen-in-space program was not held back.

When the shuttle was in its design phase, in the early 1970s, the argument was made that it should never carry more than four passengers, according to David Pendley, a retired NASA employe who handled safety planning at that time. Ejection seats could have been built for four, he said, but not for more.

Nonetheless, he recalled, there was a "big push even then to fly nonparticipants," Pendley said in a telephone interview. "I think it was crazy. Do they civilians fly with dive-bomber test pilots?"

The vehicle was built so that liftoff and reentry stress would be low so it could carry "people who were not perfect physical specimens," another former official said.

A retired Pentagon official, who worked closely with the space program for many years, confirmed Pendley's view that a crew of four was enough to handle any shuttle mission. A commander, a pilot and a payload specialist were sufficient to launch any satellites, the official said. Adding a mission specialist, he added, would permit use of the shuttle arm, repairs in space and laboratory-type experiments.

"The other three passengers in a seven-member crew," he said, "are for show."

In 1982, the first question presented to the Naugle study group in a NASA issues paper was: "What are the valid reasons for flying private citizens on the shuttle?"

The group's eventual answer, one year later, was based on a legal analysis of the Space Act. The law authorized NASA to provide the "widest practicable and appropriate dissemination of information concerning its activities and the results thereof." Based on that passage, the panel said, sending civilians on the shuttle was "for the purpose of adding to the public's understanding of space flight."

Naugle said his group did not attempt to make any judgment of risk. "We all knew there were risks involved . . . . We all assumed there would be an accident that would cause a loss of life."

In the one discussion of the subject, Naugle said panel members talked of the impact on the agency "of the loss of [Walter] Cronkite or [author James] Michener," both of whom had requested shuttle rides.

The issue of who should fly in the shuttle also included considerations about potential noncitizen passengers whose presence could aid NASA or the United States.

NASA told the Naugle panel that it was studying the possibility of sending up foreign passengers, noting the Soviet policy of using "such opportunities for foreign policy objectives," according to NASA notes of the meeting.

In addition, the notes continued, "expanded flight opportunities could offer competitive advantages in marketing shuttle vis-a-vis the growing foreign competition."

Consequently, a West German physicist went up in 1983 with the first European-built Spacelab; Charles D. Walker, a McDonnell Douglas employe, went up in 1984 and 1985 with that company's space experiment; and a Saudi Arabian prince went up in 1985 with the Arab Satellite Communications Organization's satellite.

While the purposes for putting those passengers aboard the shuttle were clear, reasons for the citizen-in-space program were often discussed in loftier terms.

Alan Ladwig, the NASA official now in charge of the Space Flight Participant Program, said the focus from the start has been on people who could "communicate" their impressions of space, including journalists, politicians and entertainers, some of whom were lobbying to be the first aboard.

Author Tom Wolfe, who chronicled the early days of the space program in "The Right Stuff," wrote after the Challenger explosion that support for the citizen program, and therefore McAuliffe's place aboard the ill-fated shuttle, was part of an insiders' battle. NASA civilians, pitting themselves against the professional astronauts, used the program for the "dismantling of Astropower," which Wolfe described as "the political grip the original breed of fighter-pilot test-pilot astronauts had on NASA.