Buzz Blog | PhysicalCentral
By: Hannah Pell
Considering how much space waste is in orbit, the need to maintain and monitor cislunar space (the region between the Earth and the Moon) is becoming an increasingly important issue. To do so effectively may require spacecraft capable of propelling longer than those currently available, and nuclear reactors may offer a solution.
Recent news progress using nuclear technology to propel extended spaceflight – from the Rocket for Agile Demonstration Program Cislunar Operations (DRACO), SpaceNukes, among others – is an opportunity to reexamine the history of this technology and identify the origins of the nuclear propulsion: the Orion project.
The beginnings of nuclear propulsion
Soon after, Ted Taylor, America’s leading atomic bomb designer at the time (though fiercely opposed to nuclear weapons), sold the idea of a nuclear-powered spacecraft to General Atomic (also jokingly referred to as “Generous Atomics” by some physicists because of their vast financial resources), and the Orion project has started. Taylor knew Ulam through collaborative work at Los Alamos and described some of their conversations about fissile explosives in a 1995 oral history interview. Taylor recruited theoretical physicist and mathematician Freeman Dyson, who effectively joined him to bolster Orion’s credibility. “If you just talked about the project, said that you were going to propel a ship with nuclear bombs, the immediate reaction was that it was crazy. … They needed people with a solid reputation to have a chance to get it approved, ”Dyson explained in the BBC documentary. Towards Mars by A Bomb. Dyson, who dreamed of interstellar travel, handled rigorous calculations, proof of concept published in Physics Today showing that nuclear propulsion was indeed a viable option for deriving potential levels of radiation exposure per launch. (His son, science historian George Dyson, is the author of a detailed account of the Orion project).
What kind of science fiction is this? (In fact, Stanley Kubrick considered using nuclear propulsion technology in the making of 2001: A Space Odyssey). Let’s see if we can convince ourselves otherwise. Or, for fun, just go try Kerbal Space Program. I’ll wait.
Orion Physics 101 Project
The propulsion of an Orion vehicle required the systematic and controlled triggering of successive nuclear explosions. You can imagine the “nuclear pulse units” being ejected one by one like on an assembly line; in fact, Project Orion scientists consulted with the Coca-Cola Company, believing that the soft drink company’s machines could be easily scaled to handle the unit, which resembled a soda can (pictured) below).
|Diagram of an Orion nuclear pulse unit. Image credit: NASA.|
Diagram of an Orion nuclear pulse unit. Image credit: NASA.
You might be wondering (quite reasonably): if explosions happened so close to the ship, wouldn’t they cause damage? The Orion design incorporated a 1,000-ton steel thrust plate mounted on dampers smoothing acceleration to levels humans could withstand, between 2 and 4g. However, there were two critical issues with the thrust plate: Calculations predicted that the plate would deteriorate (erode) if it was not shielded from repeated nuclear exposure, and that the shock waves from the explosions could. cause splinters or splinters of metal.
Declassified images of Project Orion tests. Video credit: United States National Archives.
Secrecy and militarization
The Air Force, however, agreed to help fund it, but with another price. “Officially, this had to be justified to budget officials as a military program, so they had to invent bogus military requirements for it,” Dyson explained. The Air Force’s involvement in Project Orion, initially “a translation of a sword into a plowshare” and inspired by the hope of disentangling nuclear technology from its reliance on militarization, may have marked the beginning of its fall. “Military influences were inevitably at work there. ”
Eventually, a car-sized model of the Orion spacecraft was built, and then-President John F. Kennedy visited the California site to see it in person. Managers had hoped the presidential visit would help garner additional funding and political support, but Kennedy felt the last thing the world needed was a nuclear arms race in space, especially after the Missile Crisis in Cuba. In August 1963, the International Limited Nuclear-Test-Ban Treaty was signed, thus ending the Orion program.
“Death of a project”
Despite the strength of the science, Project Orion was morally difficult for many to support. “The idea is not crazy; the idea that we can do that is crazy, ”physicist and author Arthur C. Clarke said of Project Orion. It’s a confluence of closed secrecy against a backdrop of growing anti-nuclear sentiment that hasn’t exactly garnered broad support.
Johndale Solem, the former theoretical physicist from Los Alamos, offered a succinct summary: “In general, people shy away from the idea of using nuclear explosives. I do; I recoil from this notion. Because I know we don’t have that kind of world. And I know that having nukes in space invites someone to abuse them. Indeed, Project Orion is an important reminder that scientific justifications may not inherently prove sufficient plausibility; what can be done may not be done. Nonetheless, physicists dreamed of extending humanity’s reach into the cosmos and sought out worlds beyond our own, limited and seemingly darkened by destruction. In a few ways, that feeling still rings true today.
|Artist’s conception of a spacecraft from the Orion project. Image credit: NASA|