On the subject of space, Donald Wren, a mere 6 years old, has a few basic observations to share:

Fact No. 1: It takes, Donald says, "a lot of days to get to space." When pressed for a specifics, he decides four days should do it.

Fact No. 2: Pluto, the planet, is "the coldest place." Partly, he thinks, "because it's farthest away from anything."

Fact No. 3: A booster is something "at the bottom of a rocket."

Fact No. 4: Space is fun.

Donald is a Young Astronaut.

He's one of an estimated 250,000 children in the Young Astronauts Program, a nationwide organization designed to promote the study of science, mathematics and technological subjects. The 1 1/2-year-old program, which grew out of the White House Office of Private Sector Initiatives, was having a ceremony honoring representatives of its most active chapters yesterday.

Donald sat on the floor under the overhang of the 7,000-pound Gemini space capsule at the Air and Space Museum, waiting, with nearly 300 other Young Astronauts, to be recognized. He didn't know why.

Neither did he know about Monday's Rogers Commission Report and its assessment of NASA's responsibility in the space shuttle Challenger explosion; nor did he know about O-rings and right-hand booster joints. He didn't know about public relations or image enhancement.

Donald, a Quantico resident, just knew that the last time he saw President Reagan was on TV ("He had brown hair and a suit on") and that he was going to see the president of the United States live. In person.

Andrea Brusca, a second-grader with red pigtails, had the whole scenario arranged: "I'm gonna shake his hand and then I'll put a bag over my arm and zip it up. So it won't wash away."

Nearby was fifth-grader Genevieve Hutchison, who wore a pair of blue iridescent Air and Space Museum earrings, and had her Polaroid camera slung around her neck. Asked what she was planning to photograph, she announced "Ronnie."

Reagan, her photo-subject, stood under the Wright Brothers' "Kitty Hawk Flyer" and Lindbergh's "Spirit of St. Louis" and told the assembly of Young Astronauts that "this is no time for small plans or shrinking ambitions.

"This is an age for heroes, and I think I am seeing many of them right here in this room," he said.

Referring to the Jan. 28 shuttle explosion in which seven astronauts were killed, he said, "We will make our space program safe, reliable and proud -- just as the Challenger Seven would have wanted. Our commitment to space hasn't and won't slacken one bit. In fact, it's strengthened -- because with their memory in mind, we're not only going to do everything we planned to do before, we're going to do it better."

Ten-year-old Michael Mastrangelo, who came all the way from San Francisco, was one of the Young Astronauts chosen to sit up on the dais with the president. Michael met columnist Jack Anderson (credited as "the grandfather" of the Young Astronauts Program) and Secretary of Education William Bennett. But, best of all, Michael met the president. "It was very exciting," he said. And no, he was not nervous.

Floating in a Young Astronauts T-shirt that dangled down around his knees, wearing a Young Astronauts cap and a space shuttle pin on his shirt collar, Michael said he too wanted to be an astronaut -- to "learn about the other civilizations in space." And the Challenger disaster has not changed his plans.

"Since the tragedy happened, I shook a little, but now I'm in control," he said.