Space science gets big at NASA
The benefits of Project Prometheus touted by NASA will not come easily. The project actually requires the development of three core technologies: improved RTGs, electric propulsion systems, and nuclear reactors. The first two will be relatively straightforward to accomplish, said Jerry Grey, director of science and technology policy for the American Institute of Aeronautics and Astronautics, because NASA and the US aerospace industry already have considerable experience designing such systems.
Designing nuclear reactors, though, will be a far harder challenge, Grey warns. “This is something in which our history is not very good,” he said. “The last we effort we made, something called SP-100, was a disaster in terms of cost, development time, and everything else. A lot of good technology was there, but the system never even got halfway through ground testing, much less flight testing.”
Nuclear reactors have a number of unique operations problems, Grey said, including high “nuclear-safe” orbits, the heavy mass of required shielding, and a “very serious” problem of eliminating waste heat from the spacecraft. “It’s hard to dump heat into space, and when you build a reactor that’s running at 100 kilowatts, you have to dump an awful lot of heat into space,” he said. “The radiator turns out to be 20 times bigger than the rest of the system.”
Besides the in-space challenges of developing nuclear power, there are a number of issues with simply developing and testing such technologies on Earth. “Facilities for development and testing for new nuclear systems, based on what we’ve done for old nuclear systems, are going to be horrendous: costly, going to take a long time, risky, and requiring a high level of safety precautions,” Grey said. “Until we do the proper testing, we’re not going to fly any Prometheus systems.”
Despite these considerable challenges, though, Grey is still a proponent of Prometheus. “Facilities for development are difficult to build, difficult to make safe, difficult to operate, and will take time and effort. That doesn’t mean we shouldn’t build them,” he said. “We built facilities for testing nuclear thermal rockets in this country 40 years ago.” He also noted that there were good designs for compact nuclear reactors when he was director of a nuclear propulsion research lab at Princeton University—in 1953. “It can be done; the only reason I gave you that list is to say that it’s not going to be easy.”
Technology is not the only challenge Prometheus faces. By invoking the “n-word”—nuclear—Prometheus faces a number of political and regulatory issues, ranging from extensive environmental reviews to concerns by anti-nuclear activists and the wider public about the dangers of a nuclear-powered spacecraft. Activists, for example, tried to block the launch of Cassini, which carried a relatively small amount of plutonium in heavily-shielded RTGs; one can imagine their reaction to the launch of a spacecraft carrying a nuclear reactor with a larger amount of uranium. In the wilder imaginations of some, Prometheus is seen as a stalking horse for military space nuclear power applications and the “weaponization” of space.
However, the political hurdles for Prometheus, at least in Congress, may not be as high as some fear. Kristin Svinicki, senior policy advisor to Senator Larry Craig, a proponent of nuclear power in general, said she noticed broad bipartisan support for Prometheus at a hearing about the program earlier this year. “There were senators who showed up who I didn’t even know were on that subcommittee because they never came to hearings,” she said, “who came for the specific purpose of telling the [NASA] administrator, ‘This is a good business for you to be in, and we want to support you.’”
Beyond Congress, though, is the larger, and more confusing, issue of public opinion. “Most of what the public perceives about nuclear systems is wrong,” said Grey, “but they perceive it that way, so you have to deal with it. Dealing with those public perceptions is going to have to be considered by a lot of people in a lot of different ways.”
“There are strange perceptions about public views on nuclear energy,” said Svinicki. She noted, for example, a poll that showed that about 60 percent of the American public approved of nuclear power, but thought that only 30 percent of other people, including their friends and neighbors, supported it. She believes, as does NASA, that Prometheus requires a “real educational component” to talk about the realities of nuclear power, and agrees with NASA’s plans to make the project as open a process as possible.
Ultimately, said Hartman, it will come down to whether the public is interested enough in exploration to fund Prometheus. “The laws of physics cannot be broken: if you want to go to the outer planets, if you want to be an explorer of this solar system, if you want to understand comparative planetary biology and where we came from, you’re going to have to fund this,” she said. “It’s an American question. We have the capability to do it, we have people who are interested in doing it, but the American public pays for it, so ultimately it’s their choice.”