Climbing the steep learning curve to space
by Jeff Foust
|A one-team event might not seem much like a contest, but the real competition was not between teams, but between vehicles and the constraints of the race.|
Last year’s event was a one-day exposition that was primarily a demonstration of some small-scale rocket-powered vehicles, like XCOR Aerospace’s EZ-Rocket (see “A day at the space show”, The Space Review, October 11, 2005). The 2006 Wirefly X Prize Cup, a two-day affair on October 20–21, held again at the Las Cruces International Airport in New Mexico, featured many similar demonstrations, from high-powered amateur rocket flights to a rocket man, a rocket bike, and a rocket truck. However, unlike last year’s event, this year’s event did have a competitive flavor, provided to some degree by the Space Elevator Games (tether strength and ribbon climber competitions) and to a greater degree by the Northrop Grumman Lunar Lander Challenge. That event proved to be the centerpiece of the Cup, despite the fact that it was a contest with only one competitor. Besides being exciting and photogenic, the competition demonstrated the technical difficulties involved with these efforts, but also the rate of innovation by and the resiliency of those trying to open the door to space ever wider.
For this year’s inaugural Lunar Lander Challenge, four teams registered to compete for $2 million in prize money offered by NASA’s Centennial Challenges program: Acuity Technologies, Armadillo Aerospace, Masten Space Systems, and Micro-Space. However, by the week of the Cup, there was going to be, at most, one competitor: Armadillo Aerospace. Acuity and Masten had decided in the weeks preceding the event that their vehicles would not be ready to fly, and even if Micro-Space’s vehicle would be technically ready to fly, they had considerable paperwork to complete before getting an experimental permit from the FAA’s Office of Commercial Space Transportation, a requirement to be able to fly at the Cup. That left only Armadillo, who did not win final approval from the FAA to participate until Thursday.
A one-team event might not seem much like a contest, but the real competition was not between teams, but between vehicles and the constraints of the race. Level one of the Challenge required vehicles to fly to an altitude of 50 meters, travel 100 meters downrange, and land on a pad just a few meters across, while remaining in the air for at least 90 seconds. Then, after refueling, the vehicle had to make the return trip, with the same altitude and time requirements, while overall taking no more than two and a half hours from the time the team left a staging area on the airport tarmac until they returned. A more difficult level two increased the hover time to 180 seconds and replaced the flat landing pad with a rough surface intended to more accurately simulate lunar terrain.
Armadillo brought two identical vehicles, Pixel and Texel, to compete for both levels of the Challenge. Their plan was straightforward: fly Pixel on Friday to win the level one challenge, they try flying Texel on Saturday for level two. If all went well, Armadillo would go home with $350,000 for winning level one and $1 million for level two. However, Murphy’s Law threw more than a few complications into those plans.
|“It was very durable: we were able to drop it in the dirt several times in the last few days here and it kept getting up and flying again,” Carmack said of his vehicle, Pixel. “But it’s probably down for the count now.”|
Armadillo’s first attempt at the level one prize came on Friday afternoon. After icing in their liquid oxygen (LOX) lines (caused, apparently, by having to store their vehicles outside overnight rather than in a hangar as expected) caused a brief delay, Pixel lifted off on the first leg of its journey. The flight appeared to go well all the way through landing, but a few minutes after landing Cup officials reported that at least one of the lander’s legs broke on landing; that caused the engine exhaust to impinge on and burn some wires. Pixel would not be able to fly back and win the level one prize.
The problem, Carmack said in a post-flight interview, was with the descent speed. “The flight was completely nominal, we landed on the pad, but we came down a little bit hard and broke some of the legs off of the vehicle,” he explained. They had planned for the vehicle to descend at 1.5 meters per second, but instead it came down at 2 m/s. Had it not been for the damaged wires, he said they would have tried to make the return flight. “I was fully prepared to fly the vehicle back on essentially bloody stumps, but we wound up cooking a couple wires also.”
Friday ended with the question of whether Armadillo would be able to repair Pixel or instead decide to fly its other vehicle, Texel. At sunrise on Saturday that question was answered when a trailer carrying Pixel arrived at the staging area. Overnight the Armadillo team had replaced the broken legs on Pixel by taking them from Texel, replaced the damaged wires and added additional insulation to them to prevent them from being burned again, and tweaked the flight software to lower the vehicle’s descent rate. Pixel was ready for another shot at the level one prize. If its Saturday morning flights were successful, Armadillo was still considering flying Texel for the level two prize, or else fly a long-duration demonstration flight.
Like the Friday flight, all seemed to go well Saturday morning until the landing. This time around, the issue wasn’t descent speed but landing accuracy. The vehicle landed right on the edge of the concrete pad, with two legs on the pad and two in the dirt. The uneven footing caused Pixel to tip over onto its side.
Fortunately, the vehicle wasn’t damaged, and was soon towed back to the staging area to be dusted off and checked out for one final attempt in the afternoon to win the level one prize. The off-center landing, Carmack said, was because of a lag in the controls: he was flying Pixel manually using a downward-looking camera on the vehicle to determine his position. “It’s got this very long control response,” he said shortly after the flight attempt. Exacerbating the situation is that at a set time the vehicle goes into an “auto-land” mode where it nulls out any horizontal motion, making it impossible to further maneuver the vehicle. “I’m probably going to be changing things in the future to make it more responsive now that I’m more comfortable” with steering the vehicle manually, he said.
Carmack and his team had one final chance to win the level one competition Saturday afternoon. Again Pixel lifted off and flew perfectly to the landing site, this time landing completely on the pad (albeit only 15–20 centimeters from the edge). This cleared the way for a return trip that, if successful, would net Armadillo $350,000. There was only one problem: one of the lander legs had broken off on landing. The Armadillo crew propped the vehicle back onto the broken leg and refueled it for liftoff, hoping for the best.
However, Murphy struck again. As the engine ignited and throttled up to full thrust, the exhaust kicked out the broken leg. Unable to support its weight yet under engine thrust alone, the vehicle started to tip to one side. The tilt triggered a safety abort that shut down the engine. The result: Pixel rose a couple meters into the air, then fell back to earth, landing on its side. Armadillo’s bid to win the Lunar Lander Challenge had come to an unfortunate end.
It also meant the end of the line for Pixel, which suffered a cracked seam in one of its LOX tanks after the latest crash. “It’s probably not going to fly again,” Carmack said in a post-flight interview. “It was very durable: we were able to drop it in the dirt several times in the last few days here and it kept getting up and flying again. But it’s probably down for the count now.”
Pixel wasn’t the only thing flying at the X Prize Cup, nor was it the only one to suffer from some technical problems. A few of the high-powered amateur rocket launches during the two-day event were scrubbed, and Orion Propulsion’s rocket-powered bike and truck each suffered some engine problems. At the Space Elevator Games, tucked away in a far corner of the tarmac, some of the teams were unable to get their climbers to crawl up the 60-meter ribbon.
|The 2006 X Prize Cup was clearly improved over the 2005 edition. There was more going on, things were in general better organized, and there was the spirit of competition missing from the 2005 event.|
Those glitches were indicative of the event itself, which had a number of rough edges not unexpected of an event only in its second year, and the first year of a two-day format. While the organizers created a schedule filled with events, there were at times long gaps between marquee attractions, while at other times activities were happening almost one on top of the other. While the Lunar Lander Challenge was played up, along with some crowed favorites like Dan Schlund (a stuntman who flew a rocket belt right in front of the crowd), other events got less attention. Few people who stayed through Saturday afternoon were probably aware that the Space Elevator Games were not finished when the Cup closed for the day Saturday: the tether strength competition was held late Saturday night at the county fairgrounds a few kilometers away, while the final set of climber contestants had to wait until Sunday.
However, the 2006 X Prize Cup was clearly improved over the 2005 edition. There was more going on, things were in general better organized, and there was the spirit of competition missing from the 2005 event. Even the weather was better: while the 2005 event suffered from heavy rains the night before and high winds the afternoon of the event, both days of the 2006 Cup featured cloudless skies, light winds, and seasonal temperatures.
Both the overall Cup and Armadillo’s efforts in the Lunar Lander Challenge illustrated one thing: the entrepreneurial “NewSpace” industry is in a particularly demanding phase of its development. The public’s expectations—and those of some in the industry—have risen because of past successes, like SpaceShipOne. Yes, most companies are still in the earliest phases of developing vehicles and related technologies, a phase prone to failures as new technologies and approaches are tried and often discarded. It’s a steep part of the learning curve, and even more difficult when it’s on public display.
“It’s easier than the professionals think it is, but it’s harder than the amateurs think it is,” Carmack said between flights of Pixel at the X Prize Cup. “You just can’t expect everything to work the first time.”
The approach Armadillo has taken is to develop its technologies rapidly and test them, finding out what works at what doesn’t. That allowed Carmack and his team to put together their vehicle even though final rules for the Lunar Lander Challenge weren’t released until less than six months before this year’s competition. “It was almost exactly six months from sketching this vehicle on the back of a little piece of hotel paper,” Carmack said. “In that six months we designed, built, and tested two complete vehicles that can then go through this flight. It was put together for $200,000 plus volunteer labor.”
Still, Armadillo would have appreciated a little extra time. “We really could have used an extra 30 or 60 days of testing to get ready for this,” Carmack said Friday. “The first time we moved this thing sideways more than a few feet was yesterday.”
|“It’s easier than the professionals think it is, but it’s harder than the amateurs think it is,” Carmack said of the difficulty developing his vehicle.|
One would think that Armadillo’s small group of largely volunteer workers would be depressed about coming so close to winning the level one prize but falling short. If they were, though, they weren’t showing it: as the Cup came to an end Saturday afternoon members of the Armadillo team, clad in matching blue jumpsuits, happily chatted with people who had gathered at the staging area, signing autographs and speaking optimistically about next year, when Armadillo plans to participate in the Lunar Lander Challenge again, although likely having competition from one or more other teams.
“This is not a failure year for us,” said Armadillo’s Phil Eaton. “It’s a successful year.”