The seven-man crew of the shuttle Challenger flew the 110-ton spaceliner to a smooth if noisy landing in California today, bringing home a treasure of scientific data and the first menagerie to travel in space with humans.
Two sonic booms in quick succession over Long Beach and Los Angeles triggered burglar alarms and calls to police as the shuttle's landing approach took it over those cities for the first time on its way to Edwards Air Force Base north of Los Angeles.
"I'd say we achieved better than 90 percent of our goals in orbit," mission manager Joseph Cremin said. "If I were grading our experiments, I'd put them in a category of high 'B' or low 'A'."
The two dozen white rats and two squirrel monkeys came through seven days in orbit as unscathed by the experience as Challenger and the $1 billion Spacelab it carried.
Physician/astronaut William E. Thornton, the designated animal handler throughout the mission, said: "We sure had a heck of a mission and I'm proud to say we brought 'em back alive."
Commander Robert F. Overmyer brought Challenger down out of clear blue desert skies to a perfect landing in the middle of the lakebed runway with none of the damage to its tires and brakes that its sister shuttle Discovery suffered landing on the hard concrete runway in Florida 17 days ago.
For the first time since the shuttle began flying in 1980, the National Aeronautics and Space Administration successfully flew two missions back-to-back in less than a month, the kind of flight schedule the space agency has promised for the end of the decade.
"Challenger looked great coming in this morning, it looked like it was in great shape when it landed," said Jesse W. Moore, associate administrator of NASA. "Completing two missions over the past 24 days, I'm proud to be a member of the team that did that."
Not only did Challenger return to Earth unscathed and apparently unmarked, it brought back in the European-built Spacelab an array of experiments that performed in space as well if not better than most experiments hauled into orbit on the hard-riding shuttle.
Of the 15 experiments flown on Spacelab, 12 apparently were completely successful and two at least partially so.
The biggest loser was a wide-field camera built to study the ultraviolet light of hot stars. It was never deployed.
The biggest winners were experiments to photograph the Northern and Southern lights, which send streaks of brilliant flashes at the extreme latitudes near the north and south polar regions at this time of year. Eighteen auroras were seen and photographed by Challenger's crew, who described them as "spectacular and all different."
Another winner was a laser spectrometer that for the first time was measuring from orbit the ozone layer that protects the Earth from the sun's searing ultraviolet light.
"The instrument studied the chemistry of the ozone layer in beautiful detail in the latitudes over the Earth that are most important to the Earth's inhabitants," Dr. Barney Farmer of the Jet Propulsion Laboratory said. "We made 19 observations of the ozone layer, and I would say we got more information out of those 19 than scientists had in all the previous balloon flights in the last 10 years."
Two experiments that broke down while Spacelab was in orbit were restored to service by scientist crew members who were able to fix their damaged instruments. One was an experiment to study the dynamics of droplets of fluids in weightlessness, the other an instrument that counted and measured cosmic rays striking Challenger in orbit.
The monkeys and rats that flew on Challenger were removed in their cages this afternoon and flown to the Kennedy Space Center in Florida where they will undergo careful medical examinations to see how they stood up to a week of weightlessness.
The rats will be killed and dissected so their vital organs can be examined under a microscope to see how they changed in orbit. Four rats have surgical implants in their hearts for more detailed examination of cardiovascular changes.
Although the monkeys and rats survived their flight in good shape, they littered their cages so frequently in orbit that they posed more than just a nuisance to the crew. Food and waste particles from the animals' cages frequently floated through Spacelab and into the flight deck, forcing the crew to put on surgical masks, gloves and smocks and spend hours cleaning up the mess.
The unexpected breakdown of the cages cast at least some doubt on future flights of animals with human crews aboard the shuttle. Flight surgeons want to fly four monkeys and 48 rats on a shuttle mission next year, but shuttle directors at the Johnson Space Center here will not allow another mission with animals until changes are made in the cages.
"We can't allow this episode to be repeated," shuttle program manager Glynn S. Lunney said in an interview. "Those people are going to have to fix their cages."
Johnson Space Center Director Gerald D. Griffin echoed Lunney's sentiments. Said Griffin: "We ran up against something we didn't expect, and it's something we've got to fix before we fly animals again.