Nuclear Renaissance in Space - Miller-McCune
As the U.S. prepares to relaunch domestic production of plutonium-238, the space community wishes to assure the public of its safety. Are they right?
In this, the 50th year of using nuclear energy for space missions, the U.S. is preparing to restart domestic production of a plutonium isotope that fuels space vehicles — a topic that was front and center at the recent Nuclear and Emerging Technologies for Space conference, held in The Woodlands, Texas.
Despite the utility and the necessity of using radioisotopes to power missions ranging from the Mars Rovers to the Voyager 2 probe now exploring the furthest edge of our solar system, the assembled experts said the public has a poor grasp of the safeguards in place for nuclear power in space.
“It’s widely misunderstood,” says Cornell University professor and Mars Rover principal investigator Steve Squyres. “People hear nuclear and radiation, and they immediately get nervous — with good reason. The problem is the devil is in the details, and the details in this case point a certain direction about what’s safe and what’s not.”
“I am utterly convinced there is no credible risk to human health and safety from launching,” Squyres said in an interview. “I really believe that, and I’ve looked at it hard.”
Plutonium-238 is used because its rate of radioactive decay generates sufficient heat, and hence power generation, to finish missions that span years or decades. (Its rate of decay, or half-life, is 87.7 years, compared to the 24,100 years of P-239, the stuff used in nuclear power plants and weapons.) Also, P-238 only emits alpha particles as it decays, rather than the more penetrating gamma or X-rays emitted by other radioisotopes.
Ralph McNutt, space scientist at the Applied Physics Laboratory at Johns Hopkins University and project scientist for the MESSENGER Mercury space probe, described the technology’s history and current use in an opening plenary session at the conference. “Radioisotope power systems are an enabling technology that we use on space missions to be able to go out in regions of the solar systems and do things we simply could not do any other way,” he explained.
“If you’re sending astronauts to Mars, I wouldn’t want to drive a solar-powered vehicle,” Squyres said during his public talk, covering future nuclear-powered missions in space well beyond programs in the next decade’s space plans.