Perhaps within a matter of a months, a handful of customers will board a spacecraft and fly above Earth's atmosphere to float for a few minutes, where they will presumably gawk at our planet's graceful curvature. Shortly after this, dozens, and soon hundreds, will follow. Space enthusiasts have made such promises about space tourism for nearly a decade, but in 2019 it's finally coming true.

In the last three months, Virgin Galactic has completed two crewed test flights above 80km. And with its flight-tested New Shepard launch system, Blue Origin remains on track to blast its own people into space later this year. Both spacecraft can carry up to six passengers. Neither company has begun commercial operations, but these flights appear imminent. Later this year, suborbital space tourism should finally transition from long-promised to something you can do if you're rich enough. Next year, we will likely see dozens of commercial flights.

These welcome successes have raised a question, however: just what do we call these people?

Until now, it has been fairly easy to call men and women who have gone to space astronauts (or cosmonauts in Russia, and taikonauts in China). About 560 humans have gone to space, nearly all of them into orbit, and a lucky two dozen have gone beyond. Twelve have walked on the Moon.

In 2004, the private SpaceShipOne venture clouded the picture a little bit by making a private suborbital flight. The pilots, Mike Melvill and Brian Binnie, had not trained as government astronauts, so the US Federal Aviation Administration created a new designation for them—commercial astronauts. Since then, the five crew members of Virgin Galactic's VSS Unity flights in December and February have also earned that designation. But the FAA will only recognize "crew," not passengers.

For now, there remains no official word on what to call non-crew members. Are they astronauts, too? Space passengers? Astro-nots? In the hopes of finding a consensus, we put that precise question to the companies, some bonafide NASA astronauts, and some experts in the aerospace community.

Defining space

This is not a story about the definition of space. For a long time, the generally accepted boundary of space was 100km, the so-called the Kármán line. This artificial barrier is recognized by the Fédération Aéronautique Internationale, the international record-keeping organization for aerospace. But this view is not unanimous, as the US Air Force delineated 80km as "space" for its participants in the X-15 rocket plane program.

For Virgin Galactic, this is a salient issue, because its tourist flights are likely to reach a peak altitude above 80km, but below 100km. In all of its promotional materials, the company has referred to anything above 80km as space. Harvard University astrophysicist Jonathan McDowell, has argued that orbiting objects can survive multiple perigees at altitudes around 80 to 90km and that this altitude range is consistent with the highest physical boundary of the atmosphere, the mesopause. An altitude of 80km, McDowell says, is consistent with the lower boundary of space.

Virgin's primary competitor in suborbital space tourism, Blue Origin, sees its guarantee of a flight above 100km as a valuable marketing point. The company will fly that high, founder Jeff Bezos said, because it does not want there to be any "asterisks" next to its customers' names when it comes to astronaut designation.

"One of the issues that Virgin Galactic will have to address, eventually, is that they are not flying above the Kármán line," Bezos said at a Wings Club luncheon in February. "The vehicle isn't quite capable. So for most of the world, the edge of space is defined as 100 kilometers. In the US, it's different. But I think that one of the things that they will have to figure out is how to get above the Kármán line."

The purpose of this story is not to litigate the boundary of space, however. Rather, it is to discuss what to call people who buy tickets on suborbital vehicles. They're not trained astronauts. (Many of NASA's best and brightest recruits train for five years, or more, before launching). They're not crew. Mostly, they simply had the disposable funds to buy a ticket, a free weekend, and the fortitude to strap themselves to a rocket.

The marketers

Not surprisingly, Virgin Galactic and Blue Origin both believe people who buy their tickets—$250,000 for Virgin, and an as-yet undisclosed amount for Blue—should justifiably call themselves astronauts. We asked each company for its rationale why.

Here was Virgin Galactic's response:

As you know, at Virgin Galactic our customers pre-flight are Future Astronauts and post-flight they will be Astronauts. Why? Because throughout history, any human who has flown above a certain altitude, regardless of whether it's orbital or sub-orbital, [has] been called astronauts—or cosmonauts or taikonauts. Nonetheless, as a proud US and European brand, we're delighted to stick with astronaut and follow the tradition set.

And here is what we received from Blue Origin:

Those who fly with Blue Origin will be called astronauts. They’ll be trained for spaceflight and will travel above the Kármán line, the internationally recognized boundary of space, joining the rank of other astronauts who have done the same.

There are few surprises in these responses, so now let us turn to some other stakeholders in the aerospace community.