The US government and some of its major aerospace contractors have tried to tackle the problem of reusable rockets and spacecraft for several decades, from the DC-X to the space shuttle, with mixed success. Even after spending hundreds of billions of dollars on these technologies in development and flight costs, neither the government nor its traditional aerospace contractors have mastered the art of flying vehicles to space, recovering them, and turning them around for new missions quickly and at low cost.
During the last half year, however, both SpaceX and Blue Origin have begun to demonstrate these capabilities. Although much work remains to be done, Blue Origin has already flown a suborbital rocket four times, in relatively short order, with low turnaround costs. And SpaceX has recovered five orbital rockets at land and sea and expects to refly at least one of them later this year.
Monday evening in Salt Lake City, some aerospace industry officials sat down to discuss this new development. The panel at an American Institute of Aeronautics and Astronautics forum on propulsion had a provocative title, “Launch Vehicle Reusability: Holy Grail, Chasing Our Tail, or Somewhere in Between?"
Moderator Dan Dumbacher said of the panel, “We purposefully tried to get a good cross-section of those who have been working on it." However, the panel included no one actually building reusable rockets and relied heavily on the old-guard perspective. Dumbacher himself, now a professor at Purdue University, previously managed development of the Space Launch System rocket for NASA, and he expressed doubt about the viability of reusable launch vehicles in 2014 by essentially saying that because NASA couldn’t do it, it was difficult to see how others could.
The view from traditional aerospace
The panel featured three men tied to the reusable but costly space shuttle in one way or another. Gary Payton, a visiting professor at the United States Air Force Academy, is a former shuttle astronaut. Doug Bradley is chief engineer of advanced space & launch at Aerojet Rocketdyne, which built the shuttle’s reusable engines. And Ben Goldberg is director of technology at Orbital ATK, which manufactured the shuttle's solid rocket boosters.
Goldberg expressed the most skepticism about the business case for reusable rockets. During his presentation Goldberg said Orbital ATK had studied the potential for reusability and found only a limited benefit to developing these systems and using them for missions to low-Earth orbit, geostationary transfer orbit, and exploration into deep space. “We ran a study, and a whole bunch of interesting things jumped out of this study,” he said. "One really interesting thing is the best you’re going to get is suborbital.”
Suborbital launches have the most benefit, he said, because the launch vehicle can easily return to the landing site, and this return has the lowest thermal loads during the descent. This allows for higher flight rates, and, according to the Orbital ATK study, up to a 55-percent reduction in per-mission launch costs.
Goldberg was much more dubious about the potential cost savings for orbital and deep-space missions. He took issue with claims made by SpaceX founder Elon Musk, who has said that because fuel costs account for just a fraction of one percent of launch costs, the potential exists to reduce launch costs by a factor of 100. At most, according to Goldberg, missions to low-Earth orbit can expect a 30-percent cost savings, with less for even higher-energy launches. “You’re not going to get 100-fold,” Goldberg said. “These numbers aren’t going to change by an order of magnitude. They’re just not. That’s the state of where we are today.”
The former astronaut, Payton, spent much of his presentation reviewing past efforts by the government to achieve reusable flight, including the DC-X in the 1990s as well as today’s small, uncrewed X-37, flown by the US Air Force. He said today’s market doesn’t justify the need for reusable launch vehicles, because the only way to cover the “high expenses” associated with reusability is to have a high flight rate. Several new constellations of communications satellites or space tourism might provide such a market, Payton said.
(The ethos of new space companies like SpaceX and Blue Origin has been more of a build-it-and-they-will-come idea—that existing launch costs are so high there is a hard limit on economic activity in space. By significantly lowering those costs, those companies believe, all manner of profitable activities in space will open up. This ethos is one of the critical differences between traditional space, which generally waits for a government contract to act, and new space companies betting on market forces.)
Of the panel’s traditional aerospace representatives, Bradley, from engine-maker Aerojet Rocketdyne, offered the sunniest outlook for reusable systems. “Really it seems to me we are at a crossroads,” he said. “In a few decades people are going to look back at what we’re doing today, throwing billion-dollar machines away, and think 'why did we do that?' There are good reasons for it now, but looking ahead decades, it’s going to be just commonplace that rockets and spacecraft are going to be reusable. So I say let’s get to it.”
It was an interesting perspective from the company that built reusable engines for the space shuttle but recently won a $1.16 billion contract from NASA to convert the shuttle’s main engines into expendable versions for the Space Launch System.
NASA’s big, entirely expendable rocket didn’t come up much during the panel discussion, although one might have expected it to when Dumbacher posed this question: “The US government doesn’t appear to be heavily investing in reusable launch vehicle technology. Why is that?” It’s likely the questioner meant NASA, which has indeed moved away from reusable rockets. While the panelists correctly noted that other US government agencies, such as DARPA with its XS-1 space plane, are interested in reusable launch vehicles, none brought up the SLS, which has large contracts with both Orbital ATK and Aerojet Rocketdyne.
Where’s new space?
The panel did include one person from the new space industry, Tom Markusic, chief executive of Firefly Space Systems. However Firefly’s business is centered around building small, inexpensive expendable rockets rather than trying to master reusability. “What the other guys are doing in new space is miraculous to me,” he said. “Technically, it’s just unbelievable what they’ve been able to do. Having said that I think there might be easier ways to do it.”
So where were the representatives of the new space companies actually building reusable launch systems in 2016 and flying them into space? Dumbacher addressed that question more than halfway through the two-hour discussion: SpaceX, Blue Origin, and Virgin Galactic were all invited, but “unfortunately were unable to attend due to other commitments.” Perhaps instead of debating the question, they're just getting on with the job.
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