WASHINGTON — The billionaire-backed Stratolaunch project, which promises to be the largest air-launch system in the world once completed, left some launch experts scratching their heads about the aspiring commercial launch company’s prospects and purpose.

Stratolaunch was unveiled Dec. 13 by Paul Allen, the Microsoft co-founder turned venture capitalist and philanthropist. The system will combine a massive airplane with a 117-meter wingspan and a rocket capable of delivering 6,100 kilograms to low Earth orbit and 2,300 kilograms to geosynchronous orbit.

Stratolaunch maintains a small corporate office in Huntsville, Ala., and is run full time by NASA Marshall Space Flight Center alumnus Gary Wentz. The company says it aims to bring “airport-like operations” to the launch of commercial and government payloads and eventual conduct human missions.

The importance of the latter sort of mission is paramount, according to Wentz.

“Paul’s made it clear that his long-term vision is actually to fly crew on this, and so that’s our focus forward,” Wentz told Space News in a Jan. 12 phone interview.

For now, however, the company is pacing itself. Wentz said Stratolaunch has awarded deals to all three of its primary subcontractors — Scaled Composites, Space Exploration Technologies Corp. and Dynetics Corp. — but has yet to hire a sales force to line up customers.

Wentz said that the company has called on a few potential customers, all of which are in the commercial sector. He declined to identify whose business Stratolaunch is courting. He did say that prospective payloads include small commercial satellites currently hitching rides to orbit as secondary payloads.

Stratolaunch’s first orbital demonstration mission, for which there is currently no payload, is targeted for December 2016, Wentz said.

Takeoff of the massive Stratolaunch carrier plane requires a runway at least 3,600 meters long and 46 meters wide, the company says. The aircraft’s ability to fly 2,400 kilometers before dropping its liquid-fueled booster would allow Stratolaunch to fly around bad weather to enable payloads to reach orbit on any given day.

But with the emergence of yet another commercial launch services provider, one former commercial launch executive questioned whether Stratolaunch would be able to capture sufficient business to recoup the costs of its massive carrier aircraft and exploit the reusability of the mother ship to turn a profit.


No Shortage of Launchers

Jim Maser, now the president of propulsion contractor Pratt & Whitney Rocketdyne, is the former president of Sea Launch — a commercial launch services provider that lofts satellites to orbit from a floating platform in the equatorial Pacific. He took the reins at Sea Launch in 2001 amid a price war among the world’s commercial launch providers.

From the mid-1990s through the early 2000s, Maser said, competition reduced by more than half the per-kilogram price of a commercial launch to geosynchronous orbit, the destination of most commercial satellites.

“Prior to all that competition, it was about $100 million to launch 4,000 kilograms to [geostationary transfer orbit], which is generally where commercial communications satellites want to go,” Maser said. “So that’s $25,000 a kilogram. And in the height of competition, the prices were $60 million for 6,000 kilograms. Everything was moving in the right direction, and it was down to $10,000 per kilogram. And we saw no increase in demand, whatsoever.”

Major players at the time included  Arianespace of France, International Launch Services, Lockheed Martin, Boeing and Sea Launch — then a Boeing-backed company that since has been reconstituted post-bankruptcy as a Switzerland-based joint venture with majority Russian backing.

Today, the launch services landscape is no less crowded, despite the fact that Lockheed Martin and Boeing now build and operate the Atlas 5 and Delta 4 rockets under the United Launch Alliance joint venture and the medium-lift Delta 2 is no longer in production.

Arianespace, for example, introduced a Europeanized Soyuz in 2011 and Space Exploration Technologies Corp., the Hawthorne, Calif.-based rocket maker that is subcontracting a five-engine variant of its ground-launched Falcon 9 rocket to Stratolaunch, landed its first big commercial comsat launch contracts.

“There aren’t too many people exiting, but we see an increase in the worldwide capacity for launch,” Maser said.

Commercial communications satellites are among the payloads Stratolaunch is gunning for.

“There is a thriving communications satellite market for small- to medium-class communications satellites,” Stratolaunch board member and former NASA Administrator Mike Griffin said at the company’s Dec. 13 press conference. “This would make a very effective launcher for such things.”

Griffin also said that Stratolaunch had its eye on a government market that produces “unmanned scientific satellites of one kind or another … at least half a dozen or so a year.” Most of these, he said, would be NASA payloads; a few would be military.

In fact, even as some questioned the merits of Stratolaunch’s business and technical approach, others debated whether Allen’s project might be a cover for, or at least squarely aimed at, military space operations.

In the days following the Stratolaunch announcement, bloggers and Internet commentators — conservative space analyst Rand Simberg principal among these — pointed out that the Stratolaunch system possesses not only the power to send an experimental U.S. Air Force space plane into low Earth orbit, but also the ability to fly hundreds of miles out over the open ocean before launching it.


The X-37 Connection

Much of the chatter about Stratolaunch’s military applications centered around using the carrier plane and rocket to launch the X-37B, a reusable Boeing-built space drone currently in the hands of the U.S. Air Force. On March 5, the service sent an X-37B on its second mission into space from the Cape Canaveral Air Force Station aboard a United Launch Alliance Atlas 5. The 5,000-kilogram spaceplane, which can stay in space for about nine months, is light enough to launch aboard the Stratolaunch booster.

The appointment of Susan Turner as Stratolaunch’s chief operating officer further fueled speculation that the air-launch system is being designed — at least in part — to deploy the X-37B. Now one of Stratolaunch’s two fulltime employees, Turner worked at NASA under Wentz in the late 1990s as the deputy manager of the X-37 project, which was a joint NASA-Air Force undertaking at the time.

Wentz said that Stratolaunch had not approached the military about conducting any launches.

As far as launching the X-37B or any follow ons, “we would consider it, sure,” Wentz said. But “until we prove reliability, trying to carry a payload of that magnitude is probably not in the cards for us.”

An air-launch expert not affiliated with Stratolaunch said launching X-37B from a mobile platform offers some operational advantages since classified satellites can be tracked fairly easily if launch locations and times are known.

“From a national security perspective, once one is more than about 200 nautical miles [370.4 kilometers] offshore, the launch isn’t visible by land-based observers so there is a degree of stealthiness that can be provided,” said Gary Hudson, an aerospace engineer who co-founded AirLaunch LLC, a company whose Pentagon-funded venture concluded in 2008 with the test firing of a booster designed to be dropped out the back of a military cargo plane.

Besides launching out of sight of land-based observers, an air launch also makes same-day on-orbit rendezvous with other space-going objects simpler. Orbital mechanics affect how quickly, or not, an object launched from the ground can reach an object in space. Depending on the location of the object in space, a ground-launched spacecraft might need days to synch up its orbit with its target’s. An air-launched payload, on the other hand, can be carried prelaunch to a location that allows for quicker access to the desired orbit.

“First-orbit rendezvous has advantages for satellite inspection and interception as well, obviously,” Hudson said.

An orbital analyst formerly with the U.S. Air Force offered a counterpoint.

“Broadly put, I think air-launch systems in general can provide some covert benefits, but the value is limited and has drawbacks,” said Brian Weeden, technical adviser at the Secure World Foundation, a think tank based here.

“Looking specifically at Stratolaunch and the X-37B, I don’t think it is a good fit,” Weeden said. “Airplanes still have to file flight plans, especially massive aircraft like Stratolaunch, and it is unlikely they would be able to take off and land unobserved.”

Spacefaring nations, and nations with good space observational capabilities, also have options when it comes to tracking a launch over open waters, Weeden told Space News.

“There are two main ways to detect a space launch. The primary way is using infrared [IR] imaging satellites, which can detect the heat from a rocket plume,” Weeden said. “Given that air-launch systems still need a pretty beefy rocket to get the payload to orbital altitude and velocity, the rocket will almost certainly be detected by these types of IR-sensing systems, although at the moment only the U.S. has any sort of global coverage.”

Other nations with infrared sensing capabilities include France and Russia, Weeden said.

Nations without such a satellite constellation can still track orbital objects from ground- or space-based observatories. By creating a catalog of objects on orbit, observers can tell when a new object appears.

Again, Weeden said, the United States has the best such network — but Europe, Russia and China all have catalogs, and amateur astronomers are building up their own database through the Internet grapevine.

Dan Leone is a SpaceNews staff writer, covering NASA, NOAA and a growing number of entrepreneurial space companies. He earned a bachelor’s degree in public communications from the American University in Washington.