When is an astronaut not an astronaut?

Gareth - No.

Eleanor - I don't know. To me it felt like space based tourists, which is also really awesome.

Harry - That's a good answer that we might come to shortly. Andrew, what about you? Yes or no?

Andrew - I think no. And I think the worst part of it was that Jeff Bezos seemed to insist on being referred to as 'astronaut Jeff Bezos' thereafter. Even if they are called astronauts, it's not a title.

Harry - Chris Riley, your our space junkie for today. What are your views on this?

Chris - You have got to examine a bit of the backstory on this. Where does space begin? It's a thing called the Karman line, which is defined by the amount of air density that you need to give lift to a wing to give you powered flight. And if you go higher and higher, the density of the air gets lower and lower until you can't actually get any lift from a wing.You can't steer a vehicle using a wing because it doesn't interact with the fewer atoms and molecules in the air to give you any sort of force. That's the Karman line. It sits at around about a hundred kilometres or 60 miles. Back in the 1960s, the US airforce had a few pilots flying these rocket planes called the X-15 planes. And they said it'd be really nice if our brave X-15 pilots and my God, they were brave. If any of you have seen the film first, man you'll know how terrifying it was to fly those aircrafts. They said, they are only going up to about 80 kilometres, 50 miles up, and we want to give them national wings. So the air force started saying space begins at 50 miles, not 60. Now, let's spin forward a few decades and suddenly we've got tourists doing these flights. So Virgin gets up about 86 kilometres. So it goes over the US airforce defined line for the edge of space and hence in their marketing, they call it the edge of space because it's not really at the Karman line. Blue Origin well clears the Karman line at hundred kilometres, it goes up another 10 above that roughly. And of course, space X is orbital. It's staggering. The crew of inspiration4 flew pretty much higher than most space shuttle flights and space station flights have been making over the decades, up to 575 kilometers incredibly. It's really only a couple of Hubble servicing missions and the Apollo missions that have gone higher than that. So are all these people astronauts? Well, Andrew points out a good point because it's not so much a title, Astronaut Jeff Bezos. It's not a title like doctor or professor. It's a job. It's an actual job so the question is, what is that job? Well, if you look at the early outer space treaties that were drawn up to make laws about space, that would keep us all safe as human activity pushed beyond the biosphere, they define astronauts using another phrase called envoys of humankind written back in the sixties. Other laws that have been drawn up since then calling them space flight participants. But the bottom line is actually there are laws associated with these titles and those laws, hence it being a treaty, are about protecting astronauts. If they come down in another part of the Earth, in foreign lands that might do harm to them. So the term astronauts, isn't just someone who's crossed the Karman line, but a person who's owed protections in international law. And that should follow whether you're a tourist or not, of course. However, what's an interesting distinction, is that the US domestic law has been changed recently so that they have three categories of astronaut. There's crew. They're the people operating the vehicle during launch, re-entry and landing. There's a space flight participant, this phrase again, which is a person carried in a launch or a re-entry, which is more in keeping with what we're seeing here now. And then there's a government astronaut which they class probably to distinguish them from tourists. When they say mission specialists, they're not career astronauts. And this is where I have a problem, because I don't think any of these people should be called astronauts, frankly, because it requires a mindset shift. We don't call everyone who flies the Atlantic everyday, an aviator. We call them passengers. They're going somewhere to do something. There's hundreds of thousands of people at any moment of the day and night that are working in the stratosphere, but they're usually on laptops, filling in spreadsheets or doing their other jobs. Or watching a film, or eating some food up there. They're just living. And they just happened to be in the stratosphere.

Harry - That ties quite nicely in with those Russian filmmakers that have gone up to carry out a job in space, right? Their job isn't to be an astronaut. Their job is to go and direct a film.

Chris - There are a great example. Of course they are because they were no more astronauts than I'm a pilot when I fly to New York. They were just filmmakers that were up there making a film, as you say exactly. So my passionate argument here is to abolish the word astronaut unless you are a pilot.

Harry - That's right. And you can find Chris on Twitter if you've got an issue with it. I'll give that to you later on in the show. We'll try and keep it quite quick. Andrew, what would you say?

Andrew - I just thought it was wonderfully ironic that the Karman line is defined as the point above which your wing doesn't work. And yet this badge you get when you become an astronaut, it's called the astronaut wings. They clearly haven't thought this through.

Chris - I have no answer. No one's ever actually pointed that out to me, but I can't disagree with you.

Harry - You're fuelling the fire, Andrew. Eleanor, what about you?

Eleanor - I have a very important question. So talking about these space flight participants or space tourists or whatever label they're going to get, the important question is how long is it until there's going to be budget space travel, like do you see that there's going to be a FlyBe version of space?

Chris - That is a good question. I mean, I suppose it depends on what's being sold. We're ready for Branson and Bezos' ticket prices that are around the $200,000 mark. There still high price tags, but they're up there with a big adventure holiday where you've got to pay tens of thousands of pounds to climb Everest these days, for example. So they're not out of kilter with that. The question you asked is is it going to become more affordable with budget? And the short answer is, the more early adopters there are, the more people that queue up to do this sort of activity, the more affordable it gets. I mean, Musk thinks he can bring the kind of price down to something that's in the low tens of thousands of dollars for something that's even orbital.

Chris - He was talking about the price of a flight to Mars, which is comparable to the costs that the pilgrims had pay to sell to the new world, which is essentially the price of your house. You'd sell your house and go and live on Mars. That seems staggering because, in relative terms, it was hundreds of billions to get to the moon in today's money. And it would be trillions to get to Mars. The thought of doing that for the price of a house and however you look at this, and there are negatives and positives to this in terms of the expenditure, it's a revolution that these people have pioneered simply by hacking the rocket equation to make space vehicles re-usable. That's the revolution, it's a material science and a chemistry revolution.