When I was twelve, I got up early one morning in early May to watch the first American astronaut launched into space. Alan Shepard didn't go into orbit. He didn't even go very far, just an arc from Cape Canaveral to his splashdown site, a few miles out into the Atlantic. It was something to see, though, and I was hooked.

I watched all the Mercury and Gemini and Apollo launches and splashdowns. I knew the names of the astronauts, and I knew how far the Russians were ahead at the beginning and when we passed them.

Like everyone in the world (or so it seemed), I was riveted to the TV for the Christmas orbit of the moon by Apollo 8 in 1968, and the moon landing the following July. Those were the big ones, but every mission was a national event. I knew I was seeing history being made, live in my living room, and I couldn't get enough of it.

Part of the thrill was knowing I was seeing things that had never been done before, and that something could go wrong at any time. In those early days, though, launches were routinely scrubbed for reasons that seemed minor. It's just that the space program was at the edge of new technology, and there was no room for a minor malfunction. There were no minor malfunctions.

Somewhere along the way space shots became routine, part of the landscape, not even the top story on the news any more. Not to the astronauts and their support crews and their families, I guess, but to us, the public.

Maybe it happened when we decided that the moon was as far as we were going for now. We weren't going to explore the solar system; instead we were going to do scientific research in laboratories orbiting above us. A noble cause, but hardly as compelling as a trip to Mars (or even back to the moon) might have been.

So when the shuttle Challenger exploded on launch in 1986, I didn't know about it until I turned on the news later on that January morning. It was a national tragedy, but it turned out to be a temporary setback for the shuttle program. By 2003, it had been nearly forgotten by the jaded public. It almost became another page from a history book, until today.

The loss of the Columbia and its seven astronauts over Texas this morning is a jarring reminder that space exploration is still an adventure that requires bravery and entails risk. A disaster is one tiny glitch away at any time, and extraordinary effort is put into safeguards to make sure that doesn't happen. That's why it's such a horrific shock when it does happen.

Risk is part of living day-to-day. We take a risk when we step outside our front door. Some say we take a greater risk by staying home. When seven people take a tremendous risk for a mission that benefits more than just themselves, and could possibly benefit all of humanity, we honor them. We honor them for taking the risk, and we mourn their loss when the risk proves greater than mere mortals and their machines can withstand.