When then Marine Lieutenant Colone

Roosevelt Lafontant first started pushing the idea of a space plane for the U.S. Marine Corps in 2002, skeptics didn't even bother to suppress their laughter. But now, with a Concept of Operations (CONOPS)—a formal military document that lays out how a particular weapon system would be used—and a completed, but not yet released Pentagon road map for the technology, people are beginning to take note of the Small Unit Space Transport and Insertion, or SUSTAIN, the notional concept of a Marine space plane.

"Then the laughing subsided," says Lafontant, who now works at Schafer Corporation. "People were really talking about it, and then it got serious. Then we finally got a CONOPS; the laughter stopped completely, and people started jumping on the technology bandwagon."

After decades of unsuccessful development, military space planes are finally getting some respect. On April 19 the U.S. Air Force plans to launch the X-37B, an unmanned space plane that will circle the planet a classified number of times before making an autonomous landing. (Popular Mechanics profiled the effort as the magazine's cover story in April.) The idea of a pop-up reconnaissance platform, to be used if a satellite is not available or is disabled, is an importantrationale for the Air Force's project.

The Marines' space plane takes the Corps' slogan of "first to fight" to the extreme: It could transport a squad of Marine riflemen to anyplace on earth within 2 hours, and then extract them after their mission is complete. Though the goal is appealing—imagine delivering well-armed Marines at hypersonic speed to a suspected Osama bin Laden hideout or besieged embassy—the concept seemed outlandish to many when it was first proposed.

But as strange as sending Marines into space might sound, it would not be the first time that the Marine Corps has succeeded in pushing a seemingly impossible aircraft. It was, after all, the Marine Corps that pushed the V-22, a tilt-rotor aircraft that takes off like a helicopter and lands like an airplane, over the objections of skeptics, even keeping it alive when then defense secretary Dick Cheney tried to kill it.

Similar to the V-22, the concept of the Marine space plane has been driven by ardent supporters, and not always with the full support of their superiors. Along with Lafontant, Franz Gayl, the Marine Corps science and technology advisor, has been another driving force behind the concept. Though it's not part of his official portfolio, Gayl has dedicated his spare time to shepherding the concept to completion. The Pentagon's National Security Space Office is now putting the finishing touches on a road map for the space plane.

Though SUSTAIN shares some commonalities with the X-37B space plane, built by Boeing, it has also focused on drawing in the "new space" companies. At a 2009 meeting sponsored by the National Security Space Office (NSSO) and Air Force Security Forces Center at Lackland Air Force Base in Texas, government officials and private industry presented the technologies that could contribute to SUSTAIN. "We've batted ideas back and forth," says XCOR Aerospace CEO Jeff Greason, who was at the meeting. "It's an interesting challenge and I've been thinking about technologically how it might be done."

The idea, says Greason, is not to think of SUSTAIN as a single vehicle that will do everything. That would hold well beyond the ability of XCOR's Lynx suborbital aircraft, or any other private space vehicle. "But if you break it down, so it's not one vehicle that does a suite of capabilities, but a set of capabilities that might be done by a suite of different vehicles all working together, it begins to look more practical," he says.

The current generation of private space planes might be able to fill a suborbital mission, but at least for the time being, reaching low Earth orbit—another goal of SUSTAIN—would be out of reach, even for the most ambitious companies. Burt Rutan, the founder of Scaled Composites, notes that SpaceShipOne and SpaceShipTwo don't go anywhere near the Mach 25 needed to get to orbit. They could be placed atop a booster, but they are not designed to withstand the thermal loads of re-entry. "They would not be very good at placing satellites in orbit," Rutan wrote in an e-mail when asked about the possibility. "A designer would do better to start from scratch."

The concept also faces major bureaucratic hurdles. The Pentagon has committed no funding to the concept, nor even developed a formal requirement for such a space plane, a critical prerequisite for getting it funded. And the National Security Space Office, which created the technology road map, still hasn't signed off and released on the formal document.

But for Lafontant, even getting the concept this far is a major accomplishment. And the plan might serve as a springboard for other space planes to join the Air Force's X-37B. SUSTAIN, Gayl says, isn't primarily about a Marine space plane, it's about developing reusable launch vehicles. "The Marines just happened to be the first to document the need formally," he says. "SOCOM and Air Force Security Forces have indicated interest; each has different applications and uses in mind."

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