By Martin Redfern
BBC Radio science unit
Is it an air show or a circus? A commercial trade fair or simple entertainment?
There was one team entry for the lunar lander competition
The X-Prize Cup held on a desert airfield at Las Cruces in New Mexico last weekend was all of these.
Now in its second year, it is the premier event for space enthusiasts, attracting tens of thousands of visitors of all ages and a chance for very rich boys to show off some very big toys.
Two years ago, above the Californian desert, SpaceShip One became the first privately funded, reusable craft to fly people into space, winning the $10 million Ansari X-Prize.
Richard Branson ordered a small fleet of SpaceShip Two vehicles for Virgin Galactic, to give thrill-seeking tourists the ride of their lives into space for an opening fare of $200,000.
But that was not the end of the story. Many of the other teams that entered are still working on their own route to space and the X-Prize Foundation realised that, for comparatively little sponsorship prize-money, they could stimulate a whole new industry in personal space flight. The X-Prize Cup was born.
The X-Prize Cup is unlike any race meeting you've ever attended. There are commercial stands and displays but it is not like any trade show.
There are exhibits of rocket technology, past present and future, but it is certainly not like a museum. And there are real rocket launches, but unlike the formality of a Nasa launch, with thousands of kids joining in for the count down.
"I have a belief that we have to make space a personal experience," says Peter Diamandis, founder and chairman of the X-Prize Foundation.
Not like many other trade shows
"For too long it's just been something you've seen on TV. You may have heard about someone who knows an astronaut. Kids have to believe that it is something they can do, something they can aspire to and dream about, just as we did when we were kids."
And nothing stimulates the dreams more than a race for big prize-money. The Lunar Lander Challenge, sponsored by Northrop Grumman has a potential prize from Nasa of $350,000.
The challenge is for a craft with at least 25 kg of payload to take off vertically, hover for 90 seconds, travel a hundred metres horizontally and land precisely on a small concrete pad, then refuel and make the return journey.
There was only one entry this year, from team Armadillo, under videogames inventor John Carmack. But it was still a nail biting race to see if it could complete the course in the time limit or at all.
The vehicle, called Pixel, is essentially four big spherical fuel tanks - two of alcohol and two of liquid oxygen - with a single rocket engine in the middle and a box of electronics on top. Visitors got a chance to see it up close before it was taken a safe distance into the desert for the count down.
Controlling it must be a bit like trying to ride a unicycle. But, with his videogames experience, John Carmack was the best person to work the remote control. On the first flight, the rocket jet kicked up so much dust that he couldn't see what he was doing.
Next time, he had a downward pointing camera on the craft. But one leg missed the landing pad and Pixel tipped over at 45 degrees.
"The actual flight went perfectly" said Carmack. "This was the first time we'd gone to 50m altitude. When I got to 50m I did a little bit of positioning to see if the camera was over the pad and the trouble was I set it down where I thought the pad was supposed to be and it was 10ft off to one side."
On the next attempt, the outward flight worked perfectly, but a weight had fallen off and, after refuelling the craft was unbalanced and crashed on takeoff.
But the Armadillo team say they will be back next year after putting in a bit more practice. Then, they hope to go on to the second phase of the challenge, landing on a rocky terrain that simulates the lunar surface. And perhaps they will have other teams to compete against.
And it's not just about winning, says John Carmack. "There is a lot to be said for the inspiration factor here. We do look like this sort of garage operation and people have called us the cowboy space people and stuff like that.
"But I think the biggest benefit of what we do is to do it from the point of view where people can say 'I could probably put this together. I can turn a wrench, I could learn how to weld'. That brings it into the realm of the sort of thing where people can go ahead and do it."
Meanwhile, at the other end of the Las Cruces airfield, the Space Elevator Challenge was under way.
The idea of the space elevator was immortalised in science fiction by Arthur C Clarke.
In principle, because a satellite 36,000km above the equator orbits at the same rate as the Earth turns, if you had a strong enough material, you could lower a tether all the way to the ground and use it to climb into space with much less energy then you need for a rocket.
Such a tether is still a long way off, but with ultra strong carbon nano fibres, it is theoretically possible. For the X-Prize cup this year, 50m of nylon conveyor belt was suspended from a giant crane and robot crawlers had to reach the top against the clock. The snag was they could carry no fuel.
Space elevators were immortalised by Arthur C Clarke
The answer, according to Mathew Marcuchi of the University of Michigan team, is to ride a beam of light. "We have a set of large searchlights down at the bottom underneath the solar arrays.
We going to be shooting up as much light as we can. We have to climb about 50m high, average about a metre of second and carry as much payload as possible."
A father and son team from Kansas used a huge bank of mirrors on the ground to concentrate sunlight on their craft, risking frying their expensive solar cells.
Other teams planned to use lasers or microwave beams, but could not sort out safety issues in time. But four crawlers got to the top of the tether, though none within the time limit to win the prize. Two of the successful teams were from high schools, with members aged 17 or 18, one team from California and one from Germany.
Higher and faster
Next year, the word is that the tether will be twice as high and the crawlers will have to go twice as fast.
Also next year there should be rocket races with real rockets. This year, the technology was demonstrated by a Learjet flying a horizontal course. Next year, says Peter Diamandis, the course will be vertical and the rockets spectacular.
"We wanted to create a real visceral experience" he told the BBC. "We're building a new generation of rocket powered aeroplanes. We put a 1500-pound liquid oxygen and kerosene engine in the back that produces a 12ft-long flame.
SpaceShipOne made the first privately-funded spaceflight
"And 10 of them will be racing in this three-dimensional racetrack. The pilot will see this head-up display of rings and you on the ground will see superimposed on the giant screens augmented reality, the Raceway painted in the sky. It's Formula 1 racing in the sky, the Rocket Race League."
But the real challenge is to go all the way to space and several teams were at the X-Prize Cup displaying their plans and their technology to do just that.
Anousheh Ansari, who sponsored the original X-Prize, has just become the first female private space explorer with a 10-day trip by Soyuz rocket to the International Space Station (ISS). In spite of a post flight party in Moscow the night before, she flew in to the X-Prize Cup for an exhaustive series of celebrity appearances.
"Today, when I walked around here, seeing all these children running around with all these pictures and bags in their hands, all excited, it was really worth the long trip that I had" she told our reporter. "I'd like to see more and more prizes.
"We'll have the rocket racing next year. And I think all of that shows that the face of the space industry is changing. It's not just government's flying to space, there are a lot more people doing work in this area and it's very encouraging to see that."