Bad weather at emergency landing sites in Spain and Senegal yesterday scrubbed the launch of the space shuttle Columbia for the fourth time in 21 days, a record number of postponements for a shuttle flight and one that casts doubt on the space agency's ability to launch the 15 shuttle flights scheduled this year.

Columbia's launch from the Kennedy Space Center in Florida was rescheduled for Thursday morning, but the four delays in getting off the ground appeared to be getting on the crew's nerves.

"We've got to stop meeting like this," launch engineer Donald Weinberg told the crew as they left Columbia's cabin after being strapped in their seats for more than six hours. Replied Columbia commander Robert Gibson: "I agree. We have a bad habit going here."

The four launch delays include two scrubs in the final minutes of the countdown, delays that have cost the National Aeronautics and Space Administration $600,000 in lost fuel costs and pay for launch crews who must be kept overtime on their jobs. The fuel expense comes when supercold liquid hydrogen and oxygen boil off to the atmosphere when they are pumped out of the shuttle and back into launch pad fuel tanks.

If Columbia is not launched by Monday, it could disrupt a demanding 1986 shuttle timetable that includes two flights in March, two flights five days apart in May and three flights in September. This year's schedule includes four flights for the Pentagon, the first shuttle flight from the West Coast, and three scientific spacecraft whose total cost is more than $2 billion.

"If we can't launch by Monday, we run up against the next flight scheduled for Jan. 23," said Jesse W. Moore, NASA associate administrator for space flight. "That's when our launch crews have to start to get Challenger ready for its next flight and they can't be readying both flights at once."

Although shuttle flights often seem routine now, the latest delays in the trouble-plagued 24th shuttle mission are reminders that the shuttle program has still not reached routine flight status. Thousands of mechanical and weather-related details must be near-perfect if liftoff is to take place.

Columbia's first delay came Dec. 18 when launch was postponed one day to give crews more time to ready the shuttle for flight. The next day, the mission was scrubbed 15 seconds before liftoff when instruments indicated a high-speed turbine controlling a steering device was out of control. The third delay came 31 seconds before liftoff on Monday when instruments failed to mark the closing of a fuel valve.

Besides commander Gibson, Columbia's crew includes pilot Charles Bolden, mission specialists George Nelson, Steven Hawley and Franklin Chang-Diaz, payload specialist Robert Cenker and Rep. Bill Nelson (D-Fla.), who as chairman of the House subcommittee on space science and applications will be the second member of Congress to fly in the shuttle. Sen. Jake Garn (R-Utah) was the first.

Mission rules call for a shuttle scrub anytime both emergency landing sites at the other side of the Atlantic Ocean are closed by weather. The Moron Air Base southwest of Seville in Spain was closed yesterday by rain and heavy low-lying clouds, and a dust haze from sand blown off the African deserts obscured the runway at Dakar on Africa's west coast, the first time both runways were closed by weather.

If the shuttle loses one or two of its main engines in the first four minutes of flight, it can turn around and return to the 3-mile-long shuttle runway at Cape Canaveral, but if engine power is lost between four and seven minutes into the flight it must land at an emergency field across the Atlantic.

The emergency landing site rule is one of many equipment and weather restraints on shuttle liftoffs. All the shuttle's engines, computers, fuel cells, steering controls, fuel pumps, valves and navigation instruments must be in perfect working order for liftoff.

Fog, haze and even low-lying clouds can halt a shuttle launch. The shuttle cannot take off or land in the rain because in its high-speed liftoffs and landings, rain acts like buckshot on the tiles protecting the fuselage from the heat of friction on reentry into the atmosphere.

Since Columbia made the first shuttle flight on April 12, 1981, only nine of the 23 missions flown to date have lifted off on time. Weather has played a part in five delays, computer glitches have scrubbed four more and two launches were stopped when engines shut down prematurely on the pad. The 14 delayed missions have cost the shuttle schedule more than six months and more than $50 million.

To save time and money, the shuttle was built to land at Florida's Kennedy Space Center, the same place from which it lifts off. But only five of 23 shuttle landings have been made in Florida, costing NASA more time and money in moving crews to California's Edwards Air Force Base, where most shuttles land and are ferried to Florida for their next launch.

Most times, Florida weather forced the California landings, but since the shuttle blew a tire and one of its brake assemblies landing on the grooved concrete runway at Cape Canaveral last April, the last seven landings were moved to California.

Space officials ordered the strengthening of the shuttle's brakes and installed a new nose wheel steering mechanism, which will be tested for the first time on the Kennedy Space Center runway at the end of this flight