Rocket renaissance

ALMOST two years ago, SpaceShipOne became the first privately-built vehicle to travel into space. Although the X-15 did something similar four decades earlier, the simple, safe design and low cost of SpaceShipOne was significant—for the first time the cost of a spacecraft fell within the price range of companies and wealthy individuals, rather than just governments. That’s one reason why today at least half a dozen private spaceships at various stages of design and construction. Today, rocketry is going through a renaissance.

Stalking through the corridors of the International Space Development Conference (ISDC) in Los Angeles this year, are the men who are going to build a new generation of spaceships. While promises about cheap space travel for the masses have been made before, this time things seem different. Besides the birth of SpaceShipOne, there has been a recent shift in US legislation to encourage personal spaceflight by simplifying government licensing requirements, straightening uncertainties over liability issues and allowing paying customers to fly at their own risk in novel craft that might be dangerous.

Most importantly, though, there is money. Lots of it. More than $1 billion has been committed on ships and infrastructure. The state of New Mexico, for example, has recently started work on a purpose-built $225m spaceport, of which the state has committed $135m to funding, even though it has nothing yet to fly. The spaceport is intended to provide a launch pad for commercial operations of the second-generation suborbital vehicle SpaceShipTwo—currently being designed in Mojave, California and which may start test flights as early as next year. The commercial development of this vehicle, in itself, is costing its financial backers, Virgin Galactic based in London, $240m. One study suggests that after five years of operation, New Mexico spaceports will have led to $1 billion of spending within the state.

Meanwhile, in Dubai, another new spaceport costing $265m was recently announced by space tourism company Space Adventures, based in Arlington, Virginia. Of this sum, $30m has been committed. (Space Adventures itself, in the last five years, has made $120m in orbital spaceflight sales—taking wealthy businessmen such as Dennis Tito, to the International Space Station with the help of the Russians.) Many other spaceports, too, are being planned around the world for an anticipated new generation of tourist vehicles, some of which are still on the drawing board or have only recently come off it. But overall, the signs lead many to suspect that a lot of money is being spent on rocketry and infrastructure that has not yet been revealed.

All this enthusiasm is being generated by plans by individuals and private companies to build a variety of suborbital spaceships--craft that travel just to the edge of space and back again. Which one, though, is best and who will succeed? This is the topic of a two-page article in this week's Economist. There is also a useful chart comparing all of the main designs.

I've been researching this piece for some time and a large array of overmatter has accumulated. I'd like to thank Charles Lurio, a space consultant, and Roger Launius, a curator at the Smithsonian Air and Space Museum, for their help as their comments were left on the cutting room floor. Charles is particularly knowledgeable about hybrids and solids. He also reckons that the Space Adventures vehicle, still in design, is a solid-based rocket.


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Rocket renaissance
The Economist
May 11th 2006 | LOS ANGELES
The era of private spaceflight is about to dawn

TWO years ago next month space travel underwent its Wright-brothers moment with the first flight of SpaceShipOne. The roles of Orville and Wilbur were played by Burt Rutan, who designed the craft, and Mike Melvill, who flew it—although they were ably assisted by Paul Allen, one of the founders of Microsoft, who paid for it. Of course, history never repeats itself exactly. Unlike the brothers Wright, who were heirs to a series of heroic failures when it came to powered heavier-than-air flight, Messrs Rutan and Melvill knew that manned spaceflight was possible. What they showed was that it is not just a game for governments. Private individuals can play, too. (more...)

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Overmatter:

XCOR on why it chose an air-launched suborbital
Jeff Greason, president of XCOR Aerospace, a small aerospace company based in Mojave, California, is developing a two-person, ground-launched suborbital rocketplane. Ground launch, he says, is technically more difficult but has significantly lower unit operating costs. “We are doing it this way because our engineering tradeoffs lead us to believe it is optimum for us for our market, resources, for the skills we have. Does that mean everybody else’s idea is bad? Of course not.” The XCOR vehicle, which will be a derivative of a previous design called the Xerus. As of last October, the company has money from private investors to start work.

Space Adventures on its vehicle plans
Of the six most prominent vehicles being developed (see chart), two are launched from the air. SpaceShipTwo will launch on a purpose-built high altitude aircraft known as Eve, built by aviation designer Burt Rutan. And although plans for the Explorer have not been fully disclosed, Eric Anderson, president and CEO of Space Adventures, says it will launch from the top of a high-altitude Russian research plane the M-55X. The project, he says, will be fully funded by a venture capital group belonging to wealthy, space-enthusiast and entrepreneurial Ansari family. The Myasishchev Design Bureau, an experienced Russian aerospace organization based near Moscow, with oversight from the Russian Space agency, will build it.

Rocketplane on the stability of its XP
At first sight, the notion of converting a Learjet to a suborbital vehicle fills some with horror. However, as Charles Lauer explains, there is actually very little left of it except the fuselage. “Starting with the existing Lear gave us a frame of reference to be able to build from and saved us a year in terms of schedule,” he says. It has a new delta wing, a new v-tail, and wind tunnel studies show it has “natural stability” on re-entering the atmosphere says Mr Lauer. SpaceShipOne solved the problem of stability on re-entry with a revolutionary technique of flipping its wings in half—something called the feather. Mr Lauer says the XP has this but “without having to reconfigure our airplane twice in the course of a flight profile and that’s a more sensible way to fly”.

George Whittinghill, chief technologist for Virgin Galactic, responds, "SpaceShipTwo can re-enter in any attitude, even upside down. The feather acts like a shuttlecock, and will right the ship as soon as it hits air, without any action from the pilot. I seriously doubt that the Rocketplane can re-enter in any attitude, hands-off, righting itself. Its attitude control jets will have to position the ship just right, or it will get into trouble later on during the entry.

Dennis Tito on liquid fuels
Dennis Tito, an entrepreneur and the world’s first space tourist, says ultimately liquid fuel will make a suborbital more reusable because it is possible to “gas and go”. In other words, operations can be more aeroplane-like and this will lower costs. XCOR’s ship seems quite likely to be the smallest, and cheapest, of all the new suborbital ships. Although no timeline has been announced, one potential customer reckons that they could fly within a year and a half. The ship is also intended to fly four flights per day.

Charles Lurio on rocket design
With their premixed fuel and oxidizer, solid propellant systems have always raised safety questions. They’re tricky systems to master, as evidenced by the literally explosive difficulties that the then-Soviets had in developing them for ICBMs. As a result the USSR retained primarily liquid fueled missiles long after they were minimal parts of the US arsenal. NASA, driven by the desire to get the Space Shuttle program funded, convinced itself that solid boosters (with a lower upfront development price) were acceptable despite long-standing anxiety about the safety of putting people atop them. Of course, ‘turning off’ a solid in an abort condition - let alone restarting it in flight - is essentially impossible. Hybrids do appear to have a higher safety potential, not merely by separating fuel from oxidizer but because they can be shut off by cutting off the flow of oxidizer. As with solids, however, they have much larger combustion chambers than do liquid motors. That volume effectively ‘stores’ combustion energy, which, as one person dryly put it, “can go somewhere inappropriate in a failure [condition].” But the greatest unease that I and others have with the hybrid results from the relatively miniscule amount of existing experience in building and operating them compared to either solids or liquids. As I’ve noted, Brian Binnie had to cope with significant accelerations and vibrations while SpaceShipOne’s motor was firing (see page 60 of the February 6th Aviation Week). There are design and flight adjustments that likely would ameliorate those effects for commercial passengers. By contrast, while a solid’s acceleration can also be moderated (though not in real-time) it essentially unavoidably produces what’s not-so-fondly referred to as the ‘paint shaker effect.’ Of course, reentry forces (Mr. Binnie experienced 5.5g’s) are not directly dependent on the ascent propulsion system, and are malleable with aerodynamic design and chosen flight paths.Some of the initial passengers on the suborbital flights will want to primarily liquid fueled missiles long after they were minimal parts of the US arsenal. NASA, driven by the desire to get the Space Shuttle program funded, convinced itself that solid boosters (with a lower upfront development price) were acceptable despite long-standing anxiety about the safety of putting people atop them. Of course, ‘turning off’ a solid in an abort condition - let alone restarting it in flight - is essentially impossible.

Hybrids do appear to have a higher safety potential, not merely by separating fuel from oxidizer but because they can be shut off by cutting off the flow of oxidizer. As with solids, however, they have much larger combustion chambers than do liquid motors. That volume effectively ‘stores’ combustion energy, which, as one person dryly put it, “can go somewhere inappropriate in a failure.” But the greatest unease that I and others have with the hybrid results from the relatively miniscule amount of existing experience in building and operating them compared to either solids or liquids.