An official photo from NASA HQ.

Yesterday at 10am, this city stood still. People in suits poured from buildings, mingling with tourists who flock to the Capital year-round in patriotic attire. Photographers had impressive equipment perched on tripods pointed at the White House, framing what they hoped would be the perfect shot. Everyone looked to the heavens in anticipation.

And then she appeared - the Space Shuttle Discovery strapped to the top of a modified 747, cruising over the National Mall in what is normally restricted airspace. The crowd erupted in cheers.

As I stood watched Discovery take her final victory lap, I had goosebumps. I turned to the White House cop standing next to me and said, "It looks like they're having a blast," referring to the pilot who I assume had a shit-eating grin on his face as he did THREE fly-bys that required sign-off from the FAA, Homeland Security and the Secret Service. "Hell," he responded, "I'm having a blast!"

Just taking the sight at face value - a friggin' Space Shuttle strapped to an airplane - is jaw-dropping in a physics-defying kind of way. But it was more than that. It was one of those moments when you realize you're witnessing history, that - just as I remember where I was when I learned the Challenger blew up (Mrs. Lockery's sixth grade writing class); I will now never forget the day the Shuttle program ended. Because I saw it with my own two eyes.

In middle school, I was a member of the Young Astronauts Club. It used the sex appeal of space to interest kids in math and science, with the unstated promise that if you excelled in both, you just might get to ride in a Space Shuttle some day. With the retirement of the Shuttle, I wonder: what will fuel this generation's curiosity?

As I walked back to my office, I couldn't help but smile. And I noticed that everyone else I passed was also smiling. I suppose you can't help but share a feeling of awe and pride and hope when you've just seen something that left our atmosphere 39 times receive a well-deserved salute.

Last night over dinner, Alan and I discussed it. I told him I overheard an intelligent-looking guy on his phone right after the fly-by, saying, "I need you to explain the physics to me. How can an airplane take off with a Space Shuttle on top of it? How does it not flip over when it is in the air?"

We laughed, then Alan said, "Just think. I don't care how scary a flight is now... you can always reassure yourself by saying, 'At least we don't have a Space Shuttle strapped to the roof.'"

I pictured the first pilot who was told he'd be flying a 747 with, oh, um, a SHUTTLE attached to the top. "You want me to do WHAT?" I can imagine him asking, incredulously.

"Don't worry," the engineers would've said. "Just think of it as having an extra set of wings."

Then, once he floored it down the runway, they would've looked nervously at each other and said, "I can't believe we talked him into that. Here's hoping it actually works!"