Tuesday’s announcement of the plans by startup Stratolaunch Systems to develop an air launch system attracted considerable attention and excitement, and understandably so. The world’s biggest airplane! A “dream team” that reunited Paul Allen and Burt Rutan for the first time since SpaceShipOne! An industry team that includes Scaled Composites and SpaceX! A board that includes not just Rutan and SpaceX president Gwynne Shotwell, but also former NASA administrator Mike Griffin! And did I mention the world’s biggest airplane?
However, the more I thought about it later Tuesday and into yesterday, the more questions developed in my mind about this venture. From a technical standpoint, I don’t doubt that the Stratolaunch team has the ability to develop what they’re proposing, particularly given the experience of Scaled and SpaceX. Yes, there will be complications along the way, but these companies are as well positioned as any to deal with them.
Instead, I’ve been pondering this question: what problem does this system solve? That’s the key question for any business venture, not just a launch vehicle company. What can Stratolaunch do that others can’t do, or do as well or as cheaply? Air launch has its advantages, but also carries with it some disadvantages and other issues. That, coupled with what the company has released about its technical capabilities, leads me to wonder if the Stratolaunch system will really be that competitive over more conventional launch systems in service or under active development today.
Here are a few issues to consider:
Big plane, bigger pricetag. It’s likely the single most expensive element of the Stratolaunch system will be the aircraft. The rocket will be derived from the Falcon 9, with only four or five engines and a shorter first stage (perhaps equipped with some kind of delta wing, like on the Pegasus, according to the animation), which will reduce its development costs compared to a clean-sheet design. Developing the plane the size of what they’re planning will likely cost much more, even with their plans make use of existing 747 components, from the landing gear to its jet engines.
How expensive? The company hasn’t disclosed its development costs, beyond a statement by Paul Allen at Tuesday’s press conference where he said he expected to spent “an order of magnitude more” on this than he did on SpaceShipOne. Given that he spent $28 million on SS1, according to his memoir published earlier this year, that suggests spending around $300 million or more on Stratolaunch. And that may be still too low, as $300 million is in the ballpark for what it has cost to develop WhiteKnightTwo and SpaceShipTwo, a much smaller carrier aircraft and suborbital vehicle, respectively.
The Stratolaunch aircraft will be on a scale similar to the largest jetliners, like the 787 and A380, whose development each cost over $10 billion. Of course, those are passenger jetliners with significant certification costs, as well as upfront costs for construction of potentially thousands of such planes, while only one or two Stratolaunch planes, not intended (presumably) for passenger service, might ever be built.
The Airframe Cost Model provides an extremely basic cost model for aircraft development based on empty weight and speed. Those details aren’t available for this plane (only the gross takeoff weight, 1.2 million pounds or 540,000 kilograms, is given), but assuming a modest empty weight of 250,000 pounds—about the same as the considerably smaller 787—and a top speed of 300 knots, the model yields, for one test aircraft and one production model, a total cost of $4.7 billion (in 2004 dollars). That is almost certainly far too high: the model is based on the production of older military aircraft, including the giant C-5 cargo plane, and Scaled is likely more efficient and able to make use of more advanced technologies to reduce costs. The question, though, is the model is off by a factor of ten, or only a factor of five or less?
How flexible is air launch? One of the advantages touted by air launch proponents is the flexibility to launch from a wide range of locations. You don’t need the fixed infrastructure of a launch pad; instead, just take off from your desired airport, point the plane in the right direction, and fire off the rocket. No worries about coordinating range availability with other rockets or maintaining expensive launch pad equipment. Orbital Sciences Corporation’s Pegasus, the most successful orbital air launch system, has demonstrated that flexibility by flying from several airports from the US and overseas.
However, the sheer size of Stratolaunch—far larger than Pegasus, which uses a converted L-1011 jumbo jet—will limit that flexibility. The aircraft requires a 12,000-foot (3,650-meter) runway, sharply limiting the number of airports in the US or elsewhere it can take off from. In addition, unless the first stage is reusable and designed to fly back (which it does not appear to be from the animation), the launch will have to take place over open water or very remote unpopulated areas, further limiting the airports to those in range of those drop zones. It’s no wonder, then, that the press release identified Kennedy Space Center as one possible launch site, given its five-kilometer-long Shuttle Landing Facility runway and access to the Eastern Range.
Moreover, any airport that Stratolaunch operates from will need some infrastructure that may be unique to that system. That will include a hangar large enough to accommodate the plane’s 385-foot (117-meter) wingspan, as well as propellant storage (RP-1 and LOX for the rocket) and equipment to integrate the payload onto the launch vehicle, and the launch vehicle onto the aircraft. That suggests that the plane will likely operate from only a handful of sites unless the company can find a way to scale back those equipment requirements.
A limited market. Stratolaunch advertises that the rocket can place up to 13,500 pounds (6,100 kilograms) into orbit. The specific orbit isn’t mentioned, but it’s most likely a favorable low-inclination due-east orbit, with decreased capacities for polar and sun-synchronous orbits as well as geosynchronous orbit. That makes it comparable to the Delta 2 Heavy, the most powerful versions of that vehicle that is on the verge of retirement. While Allen and others at Tuesday’s press conference brought up the idea of eventually flying crewed spacecraft, initially their focus is on launching satellites.
The problem is that this may well be a limited market. “There is a thriving communications satellite market for small to medium-class communications satellites,” Mike Griffin said at the press conference. However, a vehicle with this stated LEO capacity can likely carry satellites weighing no more than about 2 tons to GEO; the communications satellite market today is dominated by much larger satellites, with virtually nothing that small being built today. See, for example, the FAA Commercial Space Transportation Forecasts report for more data, in particular Figure 5 and Table 5, which shows only about 1 commercial GEO satellite a year with a mass less than 2,500 kilograms projected for launch through 2020.
A more likely market is for civil and military government satellites, of which Griffin estimates that there are about a half-dozen a year that previously flew on Delta 2. However, by the time Stratolaunch enters service, no earlier than 2016, Orbital’s Antares (née Taurus 2) rocket will have been in service for some time, serving that market; even SpaceX’s Falcon 9, while more capable, may attract customers with such satellites at its currently-advertised launch costs. There are also international options for non-US Government customers, like the Soyuz (now launching from French Guiana in addition to Russia and Kazakhstan), Land Launch’s Zenit-3SLB, and the Angara that is still under development in Russia.
It may turn out that Stratolaunch can beat out those other vehicles on price when it is introduced. (Company officials haven’t disclosed a target launch price for the vehicle.) However, given the inelastic nature of many of these existing markets, a lower-priced alternative may not stimulate much, if any, additional demand. This would force Stratolaunch to compete head-to-head with other companies (including potentially SpaceX) for the limited number of launch opportunities in this portion of the market.
This analysis is incomplete, primarily because it’s based on the limited technical and business information provided by Stratolaunch so far—a luxury it has thanks to the financial backing of Allen. There may be missing pieces to its business plan that make this system far less expensive to develop and operate and far more competitive in the global launch market than this analysis suggests, particularly if it can move into human spaceflight markets. Otherwise, despite being an interesting technical concept backed by an impressive team, Stratolaunch may not be that compelling in the long run.