The waste products of two monkeys and two dozen rats were loose in the space shuttle Challenger again today, forcing crew members to rearrange their tight schedule and scramble about in full surgical gear to clean up after their animal passengers.

One thing was clear: Heated discussions lie ahead before astronauts agree to fly again with a menagerie.

The five scientists running the experiments aboard the $1 billion Spacelab and the two pilots flying Challenger took it in stride, but there were moments when they acted less than pleased to be serving more as animal handlers than as astronauts.

Challenger commander Robert F. Overmyer, a Marine colonel, complained about the cabin smell, then questioned the design of experiments that put so many animals in the same spacecraft with so many men.

"Be advised we now have feces in the crew compartment the shuttle cabin and it isn't much fun, guys," Overmyer griped to the Mission Control Center in Houston. "How many years did we tell them these cages would never work?"

Whatever Overmyer meant, it was clear that the monkey and rat cages were not containing the animals' waste.

While television cameras recorded it for posterity, Overmyer, William E. Thornton, Norman E. Thagard and Lodewijk van den Berg donned surgical smocks, gloves and masks and whirled about the Spacelab cabin brandishing vacuum cleaners to suck the mess out of the cabin air. Once Thagard threw up his hands and said: "Even the vacuum cleaners aren't enough."

Mission scientist George Fichtl explained that the rats and at least one monkey were moving around "much more vigorously" in their cages than expected, which he said was likely the main reason their waste was getting out.

"We designed those cages with an air-flow control to keep the waste in the cages," he said. "Our best guess now is that the animals are so spirited and are enjoying weightlessness so much that they induced turbulence in the cage that's too turbulent to contain the waste."

The humans were not alone in their suffering. One of the two squirrel monkeys aboard apparently was still bothered with what doctors call "space adaptation syndrome," which shows up in human space travelers as a splitting headache, listless behavior and an almost complete loss of appetite.

The trouble with the animals cast at least a shadow of a doubt over future animal flights on Spacelab. The next one, scheduled for some time next year, is to carry 48 rats and four squirrel monkeys as well as a human crew.

Flight surgeons deem animal flights necessary in their attempt to find out why astronauts suffer decreases in bone and muscle, a loss of calcium, a deconditioning of their cardiovascular systems, hormone and blood chemistry changes and the headaches and listlessness that often occur in the weightlessness of space.

"I think this flight is going to teach us a lot," flight director Gary E. Coen said at the Johnson Space Center, trying to play down the situation. "I think when we come down we'll be able to review the problem, bring the two sides the astronauts and the flight surgeons together and make the necessary changes to get back on track."

Spacelab mission manager Joseph Cremin made it clear that research on animals is crucial to the future of the permanent space station where men and women will have to work for months at a time in orbit. Said Cremin: "This research is essential and we really need to find a way to keep it going."

Despite the troubles, there was one element of good news. After four days of trying, Shanghai-born physicist Taylor W. Wang started up his experiment that manipulates the movement of fluids in weightlessness.

"It's working," said a laughing Wang. "Didn't you hear the shouts down on the ground from up here?"

Wang apparently found the culprit in one of three power packs that supplies electricity to his experiment. A loose or exposed wire may have created a short circuit.

Further bad news came with the failure of a laser spectrometer that had worked flawlessly the first four days of the mission, measuring for as many as 40 different chemical molecules that cluster in the upper atmosphere and that may be the end products of pollution or interaction between pollutants and the Earth's protective ozone layer. For some unexplained reason, the gas pressure that kept the laser spectrometer working fell abruptly to almost zero and the experiment was ended.

Despite its failure, the laser spectrometer made at least 17 observations at sunset and sunrise of regions of the Earth's atmosphere that had never been so closely examined. Said mission scientist Fichtl: "We have a fantastic amount of data that will take years to analyze.