The five astronauts aboard Challenger held the first news conference in an orbiting shuttle today, answering questions that covered subjects ranging from their biggest thrill to whether they were looking forward to coming back to Earth on schedule early Labor Day.

Gathered in a circle in the cockpit, Richard H. Truly, Daniel C. Brandenstein, Dale A. Gardner, Dr. William E. Thornton and Guion Stewart Bluford II left no doubts about where they wanted to be on Labor Day. Said Commander Truly: "We have enough food for about 30 days, so we'll see you Oct. 1."

Echoed Gardner: "I want to stay as long as the food holds out." The other three agreed, declaring in unison: "My vote is to stay."

Knowing full well they have to come home on Labor Day, the astronauts conceded that they were looking forward to being the first shuttle crew to land in darkness, just as their shuttle was the first to lift off at night. The landing is scheduled for 3:20 a.m. EDT Monday at Edwards Air Force Base in California's Mojave Desert, where the weather forecast was favorable.

"Dan and I have trained and tested night landings and the night lighting systems for almost a year," Truly said in response to a question. "We're looking forward to the landing, and I don't frankly think it's going to be more difficult than a day landing."

Their biggest thrills? Brandenstein said the most exciting moments were the ride into orbit and his first sunrise in orbit: "It was just a fantastic view that is pretty hard to describe."

"It's a beautiful world down there," said Gardner, "not only the land but the oceans, and I don't think I'll ever forget it the rest of my life." Bluford and Thornton said they were humbled by what they saw of the Earth.

"When you stop and think that this may be the only spot that supports life for at least five light years away and maybe more," Thornton said, "it is a very unique spot indeed and I think one that deserves very careful assessment to our responsibilities to it."

Predictably, Bluford, the first black astronaut to fly, was asked how he felt about "paving the way" for other blacks in space, and Thornton, 54, was asked how he felt about being the oldest astronaut to go into space.

Bluford's response was quick and to the point.

"We have two black Americans that are going to be flying next year," he said. "And there will be many more black Americans flying in the future."

Thornton's reply was just as quick and to the point. "We certainly don't stop life because of a few years," he said.

"It amounts to the condition of the individual. Seriously, we should not count physical conditions by the number of years but look at the physiological age and capacities of an individual. As far as I'm concerned I'm still somewhere about 30."

Truly was asked how five men got along aboard the spaceliner with no shower and a toilet that seems to break down every mission. This time, a water valve has been leaking so frequently the astronauts have had to adjust it at least three times to get it to stop leaking.

"I think a crew of five is a good size," Truly replied. "We've stayed out of each other's way most of the time, we've done our job and we've had plenty of time to fix meals and visit with each other.

"Frankly, I look back on flight two with Joe Engle and I don't see how those two-man flights got it all done. There's so much to be done up here."

Bluford said there was more than enough room "to sort of hide and be by yourself. You can go up against the window and watch the world go by and reflect on how lucky you are to be here and how beautiful the view is."