The Space Reviewin association with SpaceNews

ISDC 2024

Twenty years after the first flight of the DC-X, some are pushing for a new wave of X-vehicles to develop RLV technologies. (credit: NASA)

Can lightning strike twice for RLVs?

Bookmark and Share

One of the key memories in the history of the DC-X program was the storm the night before the vehicle’s first flight. The summer monsoon hit the DC-X launch site at White Sands Missile Range in New Mexico, flooding parts of it. The team came together, bailing water out of trenches to get the launch site ready for the flight. And that effort paid off: on the afternoon of August 18, 1993, the DC-X lifted off the ground for the first time, demonstrating how a rocket-powered vehicle could take off vertically, hover, move horizontally, and land vertically.

“DC-X was government R&D at its finest,” said Griffin.

It was fitting, then, that on Saturday night, exactly 20 years after that storm the night before the DC-X launch, thunderstorms popped up over Alamogordo, New Mexico, as members of the DC-X team gathered for induction into the International Space Hall of Fame, run by the New Mexico Museum of Space History. As the ceremonies wound down at the induction dinner, peals of thunder echoed through the building on the campus of New Mexico State University Alamogordo, and, outside, lightning illuminated the night, as if nature was also recognizing, and celebrating, the anniversary.

The 20th anniversary of the DC-X is, for many, a bittersweet milestone. It’s an opportunity to remember the technical and programmatic accomplishments of that experimental vehicle, developed as a first step towards what’s long been the ultimate goal for many space enthusiasts: a single stage to orbit (SSTO) reusable launch vehicle (RLV). However, there have been very few steps—and plenty of missteps—along the way since then, illustrated by the lack of RLVs, SSTO or otherwise, flying today. Is it possible, and desirable, to do something like DC-X again today? Can lightning strike twice?

Many attending the anniversary event, which included conference sessions on the DC-X and the future of RLVs, certainly hoped so, singing the praises of the program and expressing a desire to do more such experimental vehicles. “DC-X was government R&D at its finest,” said former NASA administrator Michael Griffin in a speech at the induction dinner. Griffin, who previously served as deputy director of technology for the Strategic Defense Initiative Organization (SDIO), the Defense Department office that funded the development of DC-X, cited several reasons for DC-X’s excellence, from a balance of control and delegation by SDIO to the selection of the right requirements for the program.

In a speech the following day at the conference, Griffin said that X-vehicles in general can do several key things essential in aerospace development, including proving out technologies before getting locked into vehicle configurations, determining what the requirements should be for future vehicles, and demonstrating systems engineering. He lamented, though, the lack of X-vehicle development today. “It is a lapse of government science and technology policy at the very top levels that has caused our aggressive pursuit of X-vehicle programs to lapse,” he said. “I would do anything to bring it back to the forefront of public thinking.”

Government acquisition regulations also make it harder to do X-vehicles today. “Why can’t we do another vehicle like this, or another set of vehicles, that could pave the way for future launch systems?” asked Gary Payton, the former deputy undersecretary of the Air Force for space who also was at SDIO during the DC-X program. His answer was a single-page viewchart that crammed the entire defense acquisitions process onto the screen, a “horse blanket” of multicolored boxes and lines that was unintelligible to the audience—and deliberately so.

“This stuff consumes more money than we had, and takes more time than we had,” Payton said. “So that’s why nobody in the Defense Department is doing something like DC-X again.” The situation was fundamentally the same at NASA, he added.

“You’re not going to get billions of dollars for X-planes,” said Sponable, “so figure out what you can do for an affordable sum, which to me is $100–200 million.”

Constrained federal budgets would seem to make this problem even worse, but Griffin suggested it also provided an opportunity. “I would like us to be going back to the Moon and establishing a lunar base. I would like us to be seriously going to Mars, not just talking about going to Mars,” he said. “But if our fiscal constraints don’t allow us to do some of the things I would like to do, then I think the opportunity is there to put in place much lower cost, high leverage value future X-vehicle programs.”

“An X-plane can answer a lot of things if it is set up and managed properly,” said Jess Sponable, a program manager at DARPA who, as an Air Force major 20 years ago, was the SDIO program manager for DC-X. That means developing a focused set of requirements that can be achieved within a modest budget. “You’re not going to get billions of dollars for X-planes, so figure out what you can do for an affordable sum, which to me is $100–200 million.”

What specific technological and operational challenges X-vehicles should be answering, though, is up for debate. Discussions about the “right” approach to RLV development have, in the space community, had the fervor of arguments over religion, politics, and sports rivalries. That’s included debates over single-stage versus two-stage approaches, horizontal versus vertical takeoff and landing, and selection of engines and propellants for those vehicles; all issues that remain open today.

At the DC-X conference Sunday, attendees broke up into several working groups for a couple hours to examine what a new generation of X-vehicles could do to support development of RLVs. Five groups examines various engineering issues, from propulsion to structures, while a sixth examined policy issues involved in winning political support for an X-vehicle program. The results, briefed Sunday afternoon at the end of the conference, offered suggestions ranging from goals for technology development to advice to how to run a program and manage a team of engineers.

Those working group sessions were designed “to try and bring the thinking towards focusing on what can we do next in X-planes to recreate a DC-X-type of atmosphere,” William Gaubatz, the former McDonnell Douglas DC-X manager, said at the end of the conference. He added he and other organizers would examine how to summarize the work done on Sunday to move the effort ahead.

One major difference between 2013 and 1993, though, is that today there are a number of companies pursuing RLVs commercially. Most of these efforts are suborbital: Blue Origin, Masten Space Systems, Virgin Galactic, and XCOR Aerospace are all actively developing such reusable vehicles, but have concepts for orbital versions as well. SpaceX, meanwhile, is testing technologies for a reusable version of its Falcon 9 rocket with its Grasshopper demonstrator.

“Most technology demonstration efforts aimed for orbit are, in my opinion, pushing on a string,” Greason said. “If the government is going to do something, it should focus first and foremost on lowering perceived market risk.”

At the conference, some pinned their hopes on the future RLV development on those companies. “Our future in space launch, our future in space, is not so much based on what the federal government is going to do,” said Payton. “Rather, it’s the entrepreneurs and the innovators, working with local governments where needed, pushing forward to increase our capacity and improve our capabilities while reducing our costs.”

Sponable, though, argued that commercial RLVs, while promising, are not pushing the limits of technology enough. “They’re doing great things, but when I look at the technologies most of them are employing today, they are inferior to the technologies that we flew 20 years ago on DC-X,” he said. “The more technology that we can transition to them, the better off the whole industry’s going to be.”

XCOR Aerospace CEO Jeff Greason argued that the lack of cutting-edge technologies on his company’s and others’ vehicles was, in essence, a feature, not a bug. “When you’re in the commercial sector, it’s not about proving your technological manhood. It’s about making money,” he said. “Being told that this system is or is not technologically superior isn’t relevant.”

Greason argued that a focus on technology may be ill-advised for government-funded programs. “Most technology demonstration efforts aimed for orbit are, in my opinion, pushing on a string. You’re trying to lower the perceived technical risk of something most people believe we can build,” he said. “If the government is going to do something, it should focus first and foremost on lowering perceived market risk.” That can be done by stimulating demand for launch services, he suggested, like NASA has done for commercial cargo and crew transportation to the International Space Station.

Relying on the commercial sector for RLV develop carries risks, as well. The 1990s saw the rise of a number of companies that sought to develop RLVs to serve what was then forecasted to be a burgeoning market for low Earth orbit satellites for companies like Globalstar, Iridium, and Teledesic. Those RLV companies sputtered out for technical and financial reasons, the latter linked to the bankruptcy of multiple satellite companies. A visitor to Mojave Air and Space Port, home to several current RLV companies, is greeted by a monument of sorts to that previous generation: the conical Roton ATV vehicle, developed by Rotary Rocket Company in the late 1990s before it went under.

Sponable said he and Gaubatz sent a short email to Elon Musk, congratulating him on the successful Grasshopper flight. Musk’s response: “Thanks. Just continuing the great work of the DC-X project!”

That message was brought home earlier this month when John Carmack, the founder of Armadillo Aerospace, announced the company was in “hibernation” for the time being because of a lack of money after its latest reusable sounding rocket crashed at Spaceport America in New Mexico in January. “The situation that we’re at right now is that things are turned down to sort of a hibernation mode,” he said. “I did spin down most of the development work for this year” after the crash.

Carmack, discussing Armadillo briefly during a much longer talk at the QuakeCon computer gaming conference in Dallas on August 1, said work had gone slower than he expected at Armadillo, and blamed it, among other things, on a failure to build multiple versions of each of its STIG rockets and “creeping professionalism” that sought to optimize designs rather than a more rapid cycle of development and test that the company used earlier in its history. “This is chapter and verse some of the errors that NASA has done over the years, and it’s heartbreaking for me to see my own team following some of these problems,” he said.

Armadillo could come back to life, Carmack said, if he finds an outside investor. He had been funding Armadillo at a rate of “something north of a million dollars a year” out his own pocket, using “crazy money” he had set aside from his primary work as a computer games developer. “But I’ve basically expended my crazy money on Armadillo, so I don’t expect to see any rockets in the real near future unless we do wind up raising some investment money on it.”

But even if Armadillo doesn’t revive from its current hibernation, and efforts to restore X-vehicle development by government agencies falter, there’s still some promise for the future of RLVs. Just a few days before the anniversary, SpaceX flew its Grasshopper vehicle—a vertical takeoff and landing vehicle, like the DC-X—to an altitude of 250 meters, and, for the first tine, moving it to the side 100 meters before making a precision landing.

At the conference, Sponable said he and Gaubatz sent a short email to SpaceX CEO and CTO Elon Musk, congratulating him on the successful flight. Musk’s response: “Thanks. Just continuing the great work of the DC-X project!” Perhaps the DC-X lightning will strike again.