How safe is safe enough?
by Jeff Foust
|“We need to be sure that any decision being contemplated by the White House or by the Congress are informed by our best understanding of the fundamental crew safety issues our human spaceflight program,” Giffords said.|
Much of the hearing was devoted to the projected safety of Ares 1. Joseph Fragola, vice president of Valador, described what he called the “four simple laws for safe space launcher design”: make the design as inherently safe as possible, separate the crew from the source of failure, create a “credible abort trigger set”, and include a tested, robust abort system for the crew. On the first point, he noted that it’s not enough to make the vehicle reliable: it must also be survivable, that is, if the vehicle does suffer a failure, there is still a “benign environment” for crew escape.
“From my experience, the Ares 1 vehicle is the singular vehicle that has been designed from the very moment of its inception with safety in mind,” he said. Other vehicles, he said, emphasize only launch reliability and not the conditions at the time of failure, since unlike a crewed vehicle there is no effort to rescue a satellite payload in the event of a launch accident. Fragola backed this up with a chart that showed that the Ares 1 was two to three times safer than alternative vehicles, including the Ares 5, Shuttle C, and EELV derivatives.
The safety of Ares 1 was questioned by one committee member, Rep. Suzanne Kosmas of Florida. She noted an Orlando Sentinel article published that morning that stated that according to the 2005 Exploration Systems Architecture Study (ESAS), it would take seven flights of the Ares 1/Orion system for it to achieve the 1-in-100 safety levels of the shuttle, let alone Constellation’s goal of 1-in-1,000, while current plans call for crewed flights after just one test flight. Fragola, who worked on that section of ESAS, said that safety assessment was based on the use of a new LOX/methane engine on the Orion service module that has since been dropped. “Now the immaturity is based primarily on the second stage of the Ares system,” he said, saying that “one or two test flights” are all that’s needed now to reach shuttle safety levels. (The Sentinel followed up and countered that Fragola misspoke: the safety levels in the original article were not based on the LOX/methane engine, which would have required an even larger number of missions to achieve safety levels.)
Despite the committee’s interest in commercial vehicle safety, only one of the six witnesses testifying Wednesday represented commercial providers: Brett Alexander, president of the Commercial Spaceflight Federation, an industry group, leading some observers to argue that the hearing was stacked against such providers. “Safety is paramount to everyone in this industry,” he said, citing a Wall Street Journal op-ed in October by 13 former astronauts, including Buzz Aldrin, in which they stated that they were “fully confident” that commercial providers could provide a level of safety at least equal to that by the Russian Soyuz spacecraft, and better than the shuttle.
The dichotomy among the witnesses was made clear when Giffords asked them two questions: whether they believed that commercial crew providers would be ready on the timescales indicated in the Augustine committee report (about a year before Constellation), and if there would be other markets that such vehicles could serve in addition to ferrying astronauts to the ISS. Alexander was the only one of the six to answer yes to both, saying that some companies thought it would take at least as long as what the committee indicated, while others thought it would take less time. “I do know it will take longer if we do not start now,” he said.
Other witnesses were skeptical. “I think it would be a very tough go” to be ready by 2016, former astronaut Tom Stafford said. Fragola said it was “very uncertain” commercial providers could meet that date. John Marshall, a member of NASA’s Aerospace Safety Advisory Panel (ASAP), said he stood by the group’s 2008 report, which stated that commercial providers could not “significantly” close the gap in human spaceflight after the shuttle is retired.
|“I don’t believe that Ares 1/Orion and commercial crew are competitive,” Alexander said. “You need to do both.”|
Regarding additional customers, Stafford said, “I know of no other ones.” Marshall said that ASAP recently met with officials at Orbital Sciences about their work on their commercial ISS resupply program, and asked them if they had performed a market study on additional commercial markets. The Orbital officials, he said, replied that they hadn’t because they see “no viable commercial market at this time.” (Ironically, a representative of one such potential commercial customer, Bigelow Aerospace, was sitting in the first row of the audience in the hearing room.)
While the hearing had something of a competitive undertone of commercial versus Constellation—based in large part because of the apparent preference by the Augustine committee for commercial crew options over Ares 1/Orion—Alexander tried to defuse that. “I don’t believe that Ares 1/Orion and commercial crew are competitive,” he said. “You need to do both. It’s not about which one gets there first, necessarily.”
Those comments were echoed by Giffords late in the hearing: “I hope that people don’t think that this is a competition of commercial versus NASA; it is simply not that.” However, she added that nothing she had heard had changed her mind about the safety of Ares 1. “Based on what we heard today, I see no justification for a change in direction on safety-related grounds.”
She also hinted that, at some point, a choice might need to be made between them. “If we had a sufficient budget to do everything, I’m sure that all of us on this committee would agree that this is where we would want to invest our money,” she said, referring to supporting commercial crew ventures. “But given the fact that we have finite resources,” she added, it was important to scrutinize how effective commercial providers could be.
|After all, the safest launch vehicle is the one that never flies.|
It’s easy to see how those finite resources could become more finite, with discussion about potential cuts in the NASA 2011 budget proposal—and those of other discretionary spending programs—to reduce the deficit. (That concern was clear to anyone who traveled to the hearing on Metro, Washington’s subway system: the station nearest the hearing was blanketed in ads for an initiative called “Defeat the Debt” about the national debt, complete with images of Uncle Sam as a panhandler.) If NASA’s budget does get squeezed, it may have to choose between Ares 1/Orion and commercial alternatives for access to low Earth orbit.
If that’s the case, it raises an issue not addressed at the hearing: is safety the best metric for choosing a human launch system? Is the “safer” system—at least on paper—better for the agency and the country? Some worry about what might happen to NASA should there be another accident that claims the lives of astronauts. “Safety is, and must be, on the minds of the men and women of NASA all the time,” said Rep. Pete Olson, ranking member of the subcommittee. “An accident could end NASA as we know it.”
However, exploration is inherently risky, something Giffords acknowledged in her opening remarks. “I’m not under any illusion that human spaceflight can ever be risk-free; nothing in life, of course, is,” she said. How much risk is deemed acceptable, by both those who would fly the vehicles and those who would fund them? Given that, which system, or systems, provide the most benefits—technical, economic, and otherwise—for the country? That’s a far more challenging analysis, but one that is more realistic than simply choosing the safest system. After all, the safest launch vehicle is the one that never flies.