NASA agrees to work with SpaceX on orbital refueling technology
NASA concept for an in-space propellant depot.
On Tuesday afternoon, NASA announced 19 new partnerships with 10 US companies to help bring more cutting-edge technologies closer to production use in spaceflight. There were a lot of useful engineering ideas here, such as precision landing systems and robotic plant farms, but perhaps the most intriguing one involved the rocket company SpaceX and two of NASA's field centers—the Glenn Research Center in Ohio and the Marshall Space Flight Center in Alabama.
"SpaceX will work with Glenn and Marshall to advance technology needed to transfer propellant in orbit, an important step in the development of the company’s Starship space vehicle," the NASA
states. This is a significant announcement for reasons both technical and political.
For its part, SpaceX welcomed the opportunity to help advance NASA's
, which NASA hopes will send humans to the Moon by 2024 (and, later on, to Mars). “We believe SpaceX’s fleet of advanced rockets and spacecraft, including Falcon Heavy and Starship, are integral to accelerating NASA’s lunar and Mars plans," a company spokesperson told Ars.
One of SpaceX's principal engineers behind the Starship project, Paul Wooster,
orbital refueling as one of most difficult technology challenges the company will have to overcome in order to realize its Mars ambitions.
Under some scenarios by which the company aims to send humans to Mars, a Super Heavy rocket would launch a Mars-bound Starship to low-Earth orbit. At that point, the spacecraft would need to top its fuel tanks back up in order to get its payload all the way to the Red Planet. It's estimated that five Starship launches' worth of fuel (as payload) would be required to refuel a single Mars-bound Starship in low-Earth orbit, and this would involve the transfer of hundreds of tons of methane and liquid oxygen.
Such refueling technology would also be useful for others besides NASA. "I’ve got a stack of studies that go from the floor to the ceiling that list the critical technologies needed for humans to become long-term explorers in deep space, and in-space refueling is always on the list," said Bobby Braun, a former chief technologist at NASA who is now dean of the College of Engineering and Applied Sciences at the University of Colorado Boulder. "It's the key for sustainability."
The new partnership recognizes SpaceX's maturity as a leading space transportation company, Braun said. And Glenn and Marshall are the right centers for SpaceX to partner with, even if there simultaneously exists a strong rivalry between SpaceX's low-cost rockets and Marshall's lead development of NASA's Space Launch System rocket.
NASA has previously done considerable work studying the handling, transfer of, and storage of rocket fuels such as liquid oxygen, hydrogen, and methane in space—they are difficult to work with and susceptible to boil off in the space environment (hydrogen atoms can even migrate directly through metal fuel tanks). Under the new Space Act Agreement, NASA's Space Technology program will fund the time the agency's people spend working on these problems and any agency test facilities used. In effect, teams from the company and agency will work together to solve the problem, each paying for its own part of the effort.
"The civil servants at Marshall and at Glenn are very talented in this area," Braun said. "The people at SpaceX clearly know their system, both the capabilities and the needs of the Starship architecture. The fact that they’re all going to get together in the same room, and work on the same problem, that’s tremendous."
Braun served as chief technologist in 2010, back when the Obama administration created NASA's Space Technology program to foster just this kind of innovation in America's private space industry. It was a contentious time in space policy, as the White House was pushing for more funding for new space companies—and new space ideas such as fuel-storage depots—while Congress wanted to keep NASA in the rocket-building business.
Eventually, Congress got the upper hand, putting NASA on track to build the large SLS rocket at a development cost of more than $2 billion a year. The rocket program mostly benefited the Alabama space center and was championed by Alabama State Senator Richard Shelby. The potential of in-space fuel storage and transfer threatened the SLS rocket because it would allow NASA to do some exploration missions with smaller and cheaper rockets. As one source explained at the time, "
Senator Shelby called NASA and said if he hears one more word about propellant depots he’s going to cancel the Space Technology program."
The line from other NASA officials was that as a technology, propellant depots were not ready for prime time. In 2011, former NASA Administrator Mike Griffin and current Executive Secretary of the National Space Council Scott Pace—both SLS advocates—wrote
a withering criticism
of the technology for Space News.
"Fuel depots as an element of
-term space architecture are an example of magical thinking at its best, a wasteful distraction supported by the kinds of poorly vetted assumptions that can cause a concept to appear deceptively attractive," Griffin and Pace wrote. Ironically, their chosen heavy-lift rocket for use in NASA's "near-term" architecture, the SLS rocket, remains badly behind schedule and over budget. It is unlikely to fly meaningful exploration missions for at least three or four more years and is holding up the Trump administration's Artemis plan.
Some engineers at NASA still wanted to solve the fuel storage and transfer issue in 2011 and put together a $400 million depot development plan. This would have included an in-space demonstration of the technology. They argued that both orbital refueling and large rockets were vital for a sustainable exploration plan. However, Congress never adequately funded the effort, and it fizzled into a series of lesser ground tests.
A consultant to NASA at the time, Charles Miller, was among those performing studies to show that the use of propellant depots could significantly lower exploration costs for NASA. On Tuesday, he praised the Trump administration and NASA chief Jim Bridenstine for putting the Space Technology program to good use.
"Administrator Bridenstine is clearly executing on President’s Trump’s guidance to increase commercial public-private-partnerships at NASA," Miller, now chief executive of UbiquitiLink, told Ars. "The game-changing technology that NASA has discovered is capitalism. This program proves NASA leadership has figured out the future is reusability mixed with commercial public-private-partnerships."