I TOLD MY FRIENDS I'd believe I was riding Columbia when I heard its solid rockets light. Well, I believed it when the solids lit. Your whole soul knows when the solids light. Your whole self is shaking and you know you're on the front end of the world's most powerful afterburner going straight up.

You're accelerating rapidly and the sky outside is becoming less blue but you don't say much. The discipline of the launch is not to say anything at all. There is a cadence that the capcom (capsule communicator in Mission Control) uses, and you hang on his cadence. He has a set of calls that should come at precise times and be precisely the same words each time. If he starts to vary you know you have a problem.

His cadence is so much of a litany that on the first shuttle launch, the capcom, Dan Brandenstein, wore a tie that had the 8 or 10 calls he makes written upside down so he could look down and not flub his calls. "Go at throttle up." Then: "You're go at one minute" and so on. It hasn't changed one beat through all five shuttle launches, and that's good because it means no problems.

When we got to the pad, we didn't have the Velcro holders for our cue cards on what to do if the launch was aborted. Those cue cards are the owner's manual. They tell each crewman what to do if the shuttle loses an engine and we have to land at some strange field in Africa or, even more frightening, turn that 100-ton spaceliner around and land at the Cape. Not to worry. The cue card holders were driven to the pad in a private car.

The noise suddenly stops when the solids burn themselves out. We're now running on the three main liquid-hydrogen engines and they are the most smoothly running pieces of machinery I've ever been around. It's like being driven by an electric motor that has kind of a hum. They don't make noise and they don't vibrate. There's nothing rocket- like about them. The solids are a rocket man's dream, making loud crackles and pops and sonic boom static. But the liquid engines are so quiet you don't even hear them when they shut down.

The most striking thing about circling the earth aboard Columbia is the silence of the journey -- the peacefulness that made it like being in a gondola under a hot air balloon racing across the sky.

You can't hear the orbital maneuvering engines start up when you want to change Columbia's orbit. The only way you know the ship is speeding up is if you hold something in front of your face and let go of it when the engines start. It comes back to you because of the sudden but gentle forward force. All you hear when the engines come on is the almost silent whirring of pumps and the quiet hiss of regulators. There's something magical driving you because here you are hurtling through space at 18,000 miles an hour and there's no sound of an engine anywhere.

Even when we launched our two satellites, we didn't hear a thing. When you see those satellites spin on the ground and you're in the same room, it sounds like a subway train about to run you over. In space, we looked at that monster in the payload bay, seven tons of it rotating, and you couldn't hear a whisper. You couldn't even feel a vibration. The only reason we knew our satellites were spinning was that our eyes told us it was going around.

I still have a hard time getting over the way you see the earth in three dimensions. It's no longer a flat earth like it is from high-flying airplanes. It's a globe. I like the view from airplanes, but I never remember being awestruck by the view. You are awestruck by the view from Columbia. You're no longer looking down at a roadmap of Texas where Route 10 looks just as flat from the air as it does on the roadmap. You can still see Route 10, but now you see it curving across the state. At the same time you see the Gulf of Mexico clear down to Campeche Bay.

You know the earth is round because you see the roundness and then you realize there's another dimension because you see layers of things as you look down. You see clouds towering up and you see their shadows on sunlit plains and you see a ship's wake in the Indian Ocean and brushfires in Africa and a lightning storm walking its way 1,000 miles across Australia. It's just like a stereoscopic view of all of nature, except you're 190 miles up.

One of the first things you realize is that the sky is jet black, but the sun is so bright you never see stars when you're in sunlight. You might be able to see stars if you put blinders on and looked only at the ink black sky. But I never tried it, and I never saw a single star anytime the sun was out.

Night falls in space with an abruptness that takes your breath away. I somehow pictured always knowing where the earth would be, even in darkness. Either there were going to be lights I could see, or there would be light leaking over the horizon from a soon-to- be-rising sun.

Instead, I found the blackest black I ever saw. I remember as a youngster going into Mammoth Cave in Kentucky and being taken into a room and told you're going to experience the darkest dark you've ever felt. Then they turned out all the lights. The darkness in space is just as dark. The way you find the earth in the dark is to track the stars until the stars stop. When the stars stop, that's the earth blocking their light.

It's very hard to see city lights from orbit unless you're crossing right over a large, well- lit city at night. We could see the lights of Miami and Perth and a few of the coastal Australian cities because we passed right over them. But we couldn't see the lights of New York because it was too far north.

In fact, you're not certain which way is north. It's harder keeping track of yourself in space than in an airplane..You don't know if the spacecraft is rightside up or upside down. You know your direction, but that's never related to which way your nose is pointed. You can be flying tail first, wing first or belly first and you know you're traveling east, but you have to do a deliberate mental calculation that if that's east, and the earth is down, then that must be north.

The sun truly "comes up like thunder," and it sets just as fast because of Columbia's incredible speed. Each sunrise and sunset lasts only a few seconds, but in that time you see at least eight different bands of color come and go, from a brilliant red to the brightest and deepest blue. No sunrise or sunset is ever the same. They're not like rainbows which have the same color combinations no matter where you are on Earth. The colors change and the width of the bands are different every time. And you see eight sunrises and eight sunsets every 12 hours you're there. I know I shouldn't say this -- because it's the only argument I know for air pollution -- but the most spectacular sunrises and sunsets we saw were in regions of the atmosphere where the pollution was at its worst.

Sunrises start with the faintest hints of color quicly followed by bands that taper out like a crescent into blackness at both limbs of the horizon. Suddenly the brilliant sunball peaks up over the horizon where the bands are widest, and all color disappears in an instant.

When the main engines shut down, I floated upstairs and I looked out the window and I couldn't believe it. The sun was streaming in and you could look right down at the Atlantic Ocean and I looked over and there were Vance Brand, Bob Overmyer and Bill Lenoir doing the countdown for the OMS burn (the Orbital Maneuvering System procedure to get into higher orbit) and I thought, "How in the world can you do that? Look outside!" Of course, I had a special luxury through launch. I was strictly an observer riding into space downstairs on the middeck with no chores to do until we got to orbit.

Your first day in orbit, you're like a baby deer on ice. Your feet are going out from under you, you're banging into everything and you think you need to move around like Superman with your arms held out ahead of you. Even scuba divers travel like that, and it's like an undersea world with a dreamlike quality to it where things seem to move more slowly. Fact is, you don't have to move at all like this, but it takes a long time to realize that.

In the beginning, you'll push off to go to the other side of the spacecraft and you'll push off inaccurately and wind up not going where you want to go. Of course, you put a hand out to stop yourself, but you do that awkwardly and bump all those Velcroed things off the wall and they tumble in all directions. Your next move it to collect them and stick them back where they were. Then your feet always kick something else loose.

We always seemed to be bumping into each other, laughing about it sometimes or saying excuse me or something else. But we never did any real damage because you never wind up moving very fast, partly out of caution and partly because of that dreamlike world up there.

You adapt to being weightless by getting over the curiosity of it, by trying different ways to move around. The physicists will bore you to tears saying you've got to "push through your center of mass," but you can do it with one finger and if you do it right you just float over and then put out your hand to stop yourself.

One other weird thing about weightlessness. Sometimes it's convenient to have your feet on the ceiling with your head toward the floor. But your head never says the floor is the ceiling. If you go to sleep upside down, your head will remember. If you drift off during the night and open your eyes, you're confused -- because you went to sleep knowing you were upside down and you'll want to wake up knowing you're upside down.

Being weightless has its physical effects. It's been reported that six of the 12 astronauts who have flown the shuttle have been sick in space. Some doctors say spacesickness is like seasickness. I disagree. Nobody was ever incapacitated.

None of the six shuttle astronauts who suffered space malaise have suffered it down in the middeck where there are no windows. Which maybe means it has something to do with what the eye sees looking out the big windows on the flight deck. I don't want to make too much of this, but in one case one of us was putting the sunshades up to go to sleep and he regurgitated when he looked up and saw the earth in a place he didn't expect it.

One reason I think those of us who have flown in the shuttle have had trouble adapting quickly to space is there's so much room to move around. There is a flight deck and a middeck -- an upstairs and a downstairs -- and each is fairly large. The more you move, the more you can confuse your inner sense of up and down.

That's no knock on the machine, though. Columbia is the most marvelous machine ever built. Here it went from sea level and zero velocity to 18,000 miles-an-hour 190 miles high in eight minutes. It traveled 2 million miles, and when we came back we complained that a couple of payload bay lights didn't come on. A burned out light bulb in the closet, that's what we complained about.

One thing is sure about re-entry. You know it's not a drill. The flying procedure is to slow Columbia down by 200 miles an hour, just enough so the orbit comes down and touches the uppermost reaches of the atmosphere. Thin as it is, the air up there is still enough to slow Columbia down. You feel yourself coming down first in the seat of your pants.

All of a sudden, you begin to hear the sound. Until now, Columbia has been a very silent ship, but now there is a roar or a rush that builds and builds and builds. It's the rush of air, and as thin as that air might be it's reverberating around the vehicle. The next thing you're aware of is a color on the windows that starts out with just a faint tint of rose red that gets brighter and brighter and then changes to a whiter red and then an orange pink and ultimately a white that flickers around the windows and is the fiery heat of re-entry. It's like being inside a neon light bulb.

Our pilot was Vance Brand, who took over the controls when we were 40,000 feet above the earth and moving just below the speed of sound. We came out of an overcast, dropped right down through the clouds at 15,000 feet, and there was the runway coming at us dead ahead at 340 miles an hour. Not an inch to the left or an inch to the right and we touched down so gently that Bob Overmyer called out in jest: "Houston, we down yet?"

Columbia carried us 82 times around the Earth, more effortlessly and silently than any magic carpet ever could. Like I said a marvelous machine.