On September 17, 1908, Army Lt. Thomas Selfridge made the fateful decision to get into an airplane with Orville Wright. It made sense for him to go: The Army had a deal to buy one of the Wright Brothers' planes, and Selfridge had designed and piloted a plane of his own a few months earlier. Wright had already taken two other officers for a spin without incident, and the first four circuits he took with Selfridge of Fort Myer, Virginia, went fine.

But on the fifth loop around, the right propeller cracked, hit one of the plane's guy wires, and shattered. Despite Wright's best efforts to glide down, the plane smashed into the ground. He suffered serious injuries. Selfridge suffered a skull fracture and died that night — the first ever fatality in the history of powered aviation. He was 26.

Still, we flew.

Fast forward to Friday, which saw one Virgin Galactic test pilot injured and one killed when SpaceShipTwo crashed in the Mojave desert. The tragic incident marked the first in-flight fatality for a space tourism company. (Scaled Composites, the company that built the X-Prize winning SpaceShipOne for itself and SpaceShipTwo for Virgin, suffered three fatalities in an explosion on the ground in 2007.)

There will, of course, be an investigation. Concerns have already been raised about the plastic-based fuel that Virgin Galactic recently decided to use instead of Scaled's unusual mixture of rubber and nitrous oxide; this was the first in-flight test of that fuel. We won't know the full details of how this happened, the equivalent of that split propeller in 1908, for some time.

But what we do know, and what Friday's tragedy reminds us, is this: Space flight is inherently dangerous. It is the risky, relatively untested edge of human endeavor, and we have to start treating it that way. Even SpaceShipTwo, gently delivered to 50,000 feet on the back of a plane called the White Knight, still requires massive amounts of explosive chemicals to escape Earth's gravity.

Richard Branson, Virgin Galactic's owner, has repeatedly stated that space tourism needs to be as safe as commercial flight from the get-go. Branson has pointed out that NASA has lost roughly 3% of all the astronauts it ever took to space, and joked that a "government-owned company" could "just about get away" with a loss of that magnitude, whereas his venture "can't afford to lose anybody."

But the forces of gravity and chemistry make no distinction between NASA and private companies. The Wright Brothers couldn't exactly afford to lose anybody either, but Selfridge was killed anyway. And of course, he wasn't the last. Year after year, aviators died in tragic circumstances, test flights, mistakes, mysterious disappearances. Commercial flight, when it began, was risky too, and it stayed risky for decades.

The relative safety of today's commercial travel, where the worst you're likely to experience is a long wait on the tarmac or a little turbulence in the air — this is a historical anomaly, and it was hard won.

It is natural for us to simply accept the casual miracle of air travel. Nobody wants to dwell on the engines that failed, the mistakes of tired pilots, the faulty radar. Perhaps we should remember them more, and appreciate the lessons learned from each successive tragedy.

Older readers might recall that passengers used to applaud the pilot on a safe landing; it wouldn't hurt to reinstate that habit.

Branson has surrounded Virgin Galactic with the kind of marketing that comes naturally to him. He has welcomed celebrities such as Katy Perry and Justin Bieber to the 700-strong list of people who've already bought $250,000 tickets. "Let's shoot a music video in space!" Bieber enthused the day he joined the list.

Lulled into a false sense of security by jet travel, we have come to assume space tourism will be much the same — just a shorter flight, a pricier ticket, and more in the way of weightlessness. We'll press our smartphones up to the glass; we'll chase M&Ms through the air; we'll take selfies and shoot music videos, and brag about it all back on Earth.

But it's about time we dropped that illusion. Even the name "space tourism" is a misnomer. Everyone who boards a Virgin Galactic flight, whenever such a thing happens, will be a space pioneer — and they'll assume all the risks that all pioneers in previous centuries did. Even a short flight up to the border of space, officially defined as 62 miles up, will subject passengers to all sorts of dangers we don't fully understand yet, such as ionizing radiation. This is exploration, not a safari. Nobody's a tourist yet.

Like it or not, everyone who buys a ticket for this kind of endeavor is something of a lab rat. That's not to say they shouldn't go — it is to say they, and the marketing departments that encouraged them, should understand why they're going.

"The frontier of space is far from tamed," wrote the National Space Society in an open letter to Virgin Galactic Friday. "America was always built on the courage of those who dared to explore new frontiers." Indeed it was. But Lewis and Clark didn't head west to take selfies. Neil Armstrong didn't think of shooting a music video on the moon. Pioneers assume enormous risks so that future generations don't have to; the thrill of going somewhere brand new in the human experience is tempered by the duty, the potential sacrifice.

So yes, of course, there should be a thorough investigation of the crash, a review of safety procedures, and the institution of new ones. But one of the biggest lessons we have to learn from this tragedy is that space isn't a resort. Visitors will not be tourists; not yet, and probably not for generations. We will only achieve that goal after a litany of mistakes, experiments and accidental discoveries, because that's how progress happens.

I still remember watching the X-Prize winning flight of SpaceShipOne in Mojave, back in 2004. White Knight lazily described circles in the air, delivering its cargo to the right height, and I found myself caught up in the airy notion that space flight was going to be quite civilized. You could serve cocktails on a flight like that, I thought.

Then SpaceShipOne shot from White Knight's back like a bullet, straight up and out of sight within seconds. Looking at the plume of smoke it left behind gave me a strong sense of vertigo, and for the first time in my life I understood the real ramifications of this all-important, much-misunderstood question: Do you really want to go to space?

One day in the distant future, hopefully in our lifetimes, space flight will become as routine as commercial air travel. But we will only reach that point if everyone who straps themselves into an explosive chemical rocket understands they are a potential Thomas Selfridge. They must be alive to the danger, and climb aboard anyway.