25: The Sun Snarers

What if Project Orion were taken out of mothballs? Could an Orion ship be built? Would it work?

As I tracked down the original Orion crew—interrupting their retirement with questions about asymmetric explosions, shock absorbers, pusher plates, and anti-ablation grease—I was struck by how much undocumented knowledge is about to disappear. I kept imagining the opening scene of a film: Ted Taylor having coffee after picking up the mail in Wellsville, New York; Harris Mayer dismantling a camera in Los Alamos; Jerry Astl fixing his fence in Solana Beach; Bud Pyatt doing some weapons-effects calculations at Maxwell Technologies; Burt Freeman modeling magnetohydrodynamics; Brian Dunne in his study on Mount Soledad; Freeman Dyson in his office at the Institute in Princeton. One by one, their telephones ring.

The message: Orion is being built. This time, no political obstacles, and the entire United States and Russian stockpile is at your disposal, as well as the latest codes, supercomputers, and complete data on certain directed-energy devices, that, since you now have a need to know, exist. Your Q clearance has been reactivated, and your family may join you once the existence of this project is revealed. One by one, the old-timers arrive back at Los Alamos and are ushered through maximum security into a conference room filled with colleagues they have not seen for forty years. The initial briefings to the Joint Chiefs of Staff and their Chinese and Russian counterparts begin. The chairman of the International Astronomical Union' working group on near-Earth objects is introduced....

In the screenplay, the Orion ship would take a crew of Armageddon or Deep Impact heroes to wrestle with some Manhattan-sized piece of space debris. In reality, the emergency Orion fleet would be a cluster of small, unmanned vehicles, spawned by the realization, once the incoming hazard was identified, that the defense must be launched as quickly and as redundantly as possible, getting out there with enough time to nudge the assailant away from Earth!

Sending a chemical rocket out to meet a threatening object, armed with a large nuclear warhead to blast it out of the way, is backwards, Johndale Solem of Los Alamos thinks. Multiple smaller bombs should be used to propel the interceptor, whose kinetic energy, if it gets there fast enough, can divert the threat. "The Orion aspect of it is," he tells me, in a conspicuously public part of the Los Alamos library, because the security mania is on and meeting privately might be misconstrued, "that when you look at the tactics for intercepting something that is on a terminal course with Earth, specific impulse comes very much into play. It gets you going faster, which has two parts to it. One is you get to it while it is still farther away, and the other part is that the kinetic energy you apply to it is going to be the mass times the square of that velocity."

In a three-page paper titled Nuclear Explosive Propelled Interceptor for Deflecting Objects on Collision Course with Earth, Solem goes back to Ulam's original idea and proposes an unmanned vehicle without either shock absorbers or shielding, driven by state-of-the-art 25 kg bombs of 2.5 kiloton yield. "Arming, fusing, and firing systems of artillery shells are routinely designed to withstand—1,000 g, he explains. An interceptor with similarly sturdy components can attain high velocities with only a few explosives and small shock absorbers, or no shock absorbers at all." Solem chooses as a sample target a "typical" chondritic asteroid 100 meters in diameter, weighing 14 million tons, with a closing speed of 25 km/sec, threatening us with an impact yield of 1,000 megatons if it hits Earth. The interceptor would be launched when the assailant is at a distance of 15 million km, or one week from impact, and would attempt to cause a deflection of 10,000 km to safely miss the earth. Solem estimates that a minimal Orion-type interceptor, weighing a mere 3.3 tons and without any warhead, could do the job. "The 115 nuclear explosives would have a total yield of 288 kilotons.... The time from launch to intercept is about five hours. Thus, there would be ample time to launch a second interceptor, should the first malfunction."[388] The interceptors would be launched into deep orbit by chemical boosters, and start their engines from there. It would take a 6,000-ton chemically propelled interceptor to do the same job, and it would travel so slowly that it would have only one chance.

Solem envisions a Deep-Space Protection Force of unmanned vehicles, permanently stationed at stable Earth-Moon Lagrange points, under international control. We are unlikely to act on this suggestion in advance. A last-minute Project Orion might be our only viable response to the impending apocalypse of something large enough to give us a year or so of warning, but requiring something big, fast, and, if all else fails, surface-launched, to give it a kick. That's when NASA officials would suddenly start asking, "Who were those guys who were talking about that 4,000-ton Orion, and does anyone remember what we did with those plans?"

"With good enough detection systems we'll find the Earth-crossing asteroids and know their orbits ahead of time," says Harris Mayer. "But what we don't know is whether the extinctions that have occurred in the past, and may occur in the future, are not due to comets. A comet has only one chance to hit Earth, but we have only one chance to stop it. I have a terrible feeling that we'll solve one part of the problem, the Earth-crossing asteroids, and we won't solve the other one."

In the mountains north of Los Alamos, over sourdough pancakes with Don Prickett, I discuss this with retired Air Force General Ed Giller, who forty years ago was searching for a mission to justify Orion in terms of national defense. He answers that no one at the Pentagon gave this much thought in 1958—or today. "I don't know that any agency is in charge of defending the earth from an incoming asteroid," he says. "Is that Department of Defense? NASA? How about EPA? They tackle air pollution! It's only until somebody's given the mission, and nobody will get the mission until it is taken a little more seriously than it is today."

Don and Mary Prickett have kept their sourdough culture alive for fifty-four years. "Uninterrupted?" I ask. Not quite. One winter, a caretaker inadvertently threw it out—an extinction-scale event to the Pricketts. Fortunately, Ray Gilbert, an AFSWC colleague, had been maintaining a backup, and the culture was brought back to life. We have no backup copy of life on Earth."

In late spring of 1999, out of the blue, Freeman Dyson reported that "NASA officials have booked a conference room at the Institute for Advanced Study in Princeton for Monday morning next week and are flying up from Huntsville with twelve scientists who want to talk about Orion. Do they know something we don't?"

"The invasion from Huntsville is over," Freeman wrote after the visit. "They talked as if they are seriously intending to revive Orion as a long-range option for NASA. Only a few of them knew anything about the technical details, so I spent most of the time explaining the basics. I did not argue with them about whether anything of this sort is possible in the real world. I said the most useful thing they could do is a computer simulation of the entire Orion system, using modern radiation-hydrodynamics codes for the propellant-pusher interaction, modern neutron-transport codes for the internal radiation doses, and modern finite-element codes for the mechanical structures. With the enormous improvement of machines and codes since the 1960s, they could answer a lot of the questions that we could not answer in the old days. Especially if they could do three-dimensional hydrodynamics to find out how much the turbulent mixing of propellant with ablated pusher material would increase the ablation. This was the great unknown quantity that we needed a nuclear test to measure. Nowadays they could measure it pretty well with a computer simulation. So the basic questions of technical feasibility could now be answered without a nuclear test."

NASA is dusting off the old idea, both as a prospect for future interplanetary missions and as a near-term contingency plan for asteroid and comet defense. The Nuclear Pulse Propulsion of Orion times has been renamed "External Pulsed Plasma Propulsion"—removing most references to "nuclear" and all references to "bombs." "This is a brand-new propulsion research center, and it's supposed to do all the advanced propulsion," Joseph Bonometti, an engineer at NASA MSFC in Huntsville, explains to me shortly after his visit to Princeton. "They have hired a number of outside folks, which is unusual for NASA. So I started looking into Orion. Actually, I started looking into a few other things, nuclear gas core reactors and things like that, and I said, 'Well, this is not going anywhere. There is no way the engineering is going to make this feasible,' and they said, 'Well, how about looking into this Orion thing. It's kind of crazy but think about it.' So I did and I started saying, 'Well, gee, there's some very big inherent potential here.' All the other systems, as soon as you start building hardware, you start losing the maximum Isp you thought you were going to have and you end up with half or a third of what your maximum is. Orion is just the opposite. You say: 'Well, I know I can get three thousand, and if you do it right, you can go higher.' "

I make contact with Huntsville, thinking that NASA must surely have excavated the original Orion technical reports, and will by now have found Wernher von Braun's 1964 paper arguing the merits of Orion, which repeated Freedom of Information Act requests have failed to unearth. Unfortunately, NASA has had difficulty obtaining even the basic Orion literature, and wants to obtain copies—as soon as possible—from me! After reviewing a list of the documents I have collected they select 1,759 pages of old Orion reports. A message arrives from Huntsville: "It is very sad to say that the government is unable to get me even some of the references you have and it is somewhat convoluted to say that the government (i.e., NASA) is interested in buying copies of all the references you have obtained from the government! But I am seriously saying it." I make the copies, and ship them out by two-day UPS. After filling out a seven-page Request for Quotation form, followed by an eight-page purchase order, followed by three pages of ACH Payment Vendor System enrollment forms, requiring signature by an officer of a bank, I am officially a NASA vendor/contractor and reimbursement at $.07 per page is in the works.

Several months later, I receive a draft NASA report. External Pulsed Plasma Propulsion and Its Potential for the Near Future, by J. A. Bonometti, P. J. Morton, and G. R. Schmidt. It takes the reader straight back to 1958:

For spacecraft applications, a momentum transfer mechanism translates the intense plasma wave energy into a vehicle acceleration that is tolerable to the rest of the spacecraft and its crew. This propulsion concept offers extremely high performance in terms of both specific impulse (Isp) and thrust-to-weight ratio, something that other concepts based on available technology cannot do. The political concerns that suspended work on this type of system (i.e. termination of Project ORION) may now not be as insurmountable as they were in 1965. The appeal of EPPP stems from its relatively low cost and reusability, fast interplanetary transit times, safety and reliability, and independence from major technological breakthroughs. In fact, a first generation EPPP system based on modem-day technology may very well be the only form of propulsion that could realistically be developed to perform ambitious human exploration beyond Mars in the 21st century. It could also provide the most effective approach for defense against collision between earth and small planetary objects—a growing concern over recent years.

NASA is currently conducting research on advanced propulsion technologies capable of supporting ambitious human exploration of the solar system in the early part of the 21st century. The need for high power densities eliminates all but nuclear energy sources. The emphasis on known physics and affordability limits the scope still further to fission processes. Of the fission-based concepts that have been considered in the past (e.g., solid-core nuclear thermal, gas-core, internal and external nuclear pulse), only external nuclear pulse circumvents the Isp constraints imposed by containment of a heated gas, and provides the very high power densities needed for ambitious space transportation. The physics behind creating a highly efficient fission burst is well understood, and in a vacuum, it produces a shell of ionized particles with an extremely high radial velocity. Thus, this concept of "riding on a plasma wave" is appropriately termed External Pulsed Plasma Propulsion or EPPP.

EPPP provides a technology that would allow us to seriously consider missions to the outer planets. It would also enable dramatically shorter trip times to Mars and other nearer-term destinations. The other and perhaps most compelling application for EPPP is its use in asteroid or comet defense. There is a low, but not negligible, probability of a collision with objects of sufficient size to cause catastrophic damage or an extinction-scale event. Good risk management would dictate that some effort be placed on devising countermeasures, if possible.

The ultimate hurdle in developing EPPP would be political in nature. However, there have been some important changes in the political landscape that may afford EPPP a chance where ORION failed. The Cold War is over and the fears of a large-scale nuclear conflict have abated somewhat. Unlike physics, the sociopolitical environment does change, and a propulsion system with this tremendous capability may be needed—possibly on rather short notice. Timing for development of EPPP may also be better than during the days of ORION. In many ways, international cooperation is more prevalent, and could conceivably be extended to the peaceful application of unused nuclear material. Stockpiles of fissionable material can be permanently disposed of and environmental contamination is negligible if used outside the earth's magnetosphere. Finally, the human race is at the threshold of truly exploring, developing resources and permanently inhabiting space.[389]

Did someone in Huntsville find the lost paper on nuclear pulse propulsion by Wernher von Braun? Whether anything comes of this proposal in this century or not, having fresh copies of Orion documents in NASA files increases the chances that knowledge of Orion will be preserved. But what of the rest of Project Orion's documents, and the unwritten knowledge accumulated by those who almost built Orion, the first time around? Is there any reason that the original plans for interplanetary Orion vehicles should be kept removed from public view?

Two Mars exploration vehicles in convoy: note the "space taxis" for making transfers between separate ships. Upon return to Earth orbit the crew will transfer to reentry capsules, leaving the Orion vehicles in orbit to be refitted and refueled.

At the end of this book is a list of known Project Orion technical reports. Many documents on this list are still classified "Secret—Restricted Data," whether or not they contain data that meet current standards for continued classification as S-RD. Besides preserving a detailed record of a cold war project and a review of the political arguments for and against the militarization of space, these reports constitute a collective scientific work that might be useful some day, even if, as Burt Freeman points out, "they might inhibit fresh thinking" if development was to proceed. As long as they remain secret, the whereabouts of copies, if any, will remain uncertain. Declassification is the way to ensure that copies are distributed and preserved. It is also the only way that the original authors can freely review and discuss their work.

Edward Teller wrote a short essay on secrecy titled "The Road to Nowhere," based on a tale from his Hungarian childhood about a band of runaway puppets who reach a fork in the road. One signpost points to "Nowhere" and one signpost points to "Everywhere." The puppets choose "Everywhere," get into all kinds of trouble, but eventually find their way home. "Science thrives on openness," Teller explains, "but during World War II we were obliged to put secrecy practices into effect. After the war, the question of secrecy was reconsidered, but the practice of classification continued; it was our 'security,' whether it worked or failed. We now have millions of classified technical documents. The limitations we impose on ourselves by restricting information are far greater than any advantage others could gain by copying our ideas. I do not claim that openness will never lead to trouble, but I am sure that it offers us the best possibility of getting safely home."[390]

"There really are no important secrets anymore," says my father—making one exception: information that might enable terrorists to explode a small amount of fissionable material on the first try. The records of Project Orion could be opened without revealing these details, or becoming bogged down in deciding whether Orion is a technology worth developing or not. The theoretical question of whether it is technically possible to build Orion—now or in 1958—is separate from the political question of why. Proliferation of secrecy has not stopped the proliferation of bombs. Nuclear weapons, like mushrooms, grow best in the dark. Yes, there are active military implications associated with the low-yield, directed-energy devices that could be used to propel Orion, but it may be safer to have the potential for such threats in the open than to assume that others, to whom the same knowledge of physics is available, will not figure this out for themselves. The rabbit is out of the hat. No one can put it back.

Orion was too ambitious a leap in 1958. Both sides in the debate were right. Nuclear pulse propulsion had to wait, but nuclear pulse propulsion will be back. We are the sun snarers. "That first glimmering of speculation, that first story of achievement, that story-teller, bright-eyed and Hushed under his matted hair, gesticulating to his gaping, incredulous listener, gripping his wrist to keep him attentive, was the most marvelous beginning this world has ever seen," wrote H. G. Wells, as the prospect of atomic energy began to dawn on us in 1914. "It doomed the mammoths, and it began the setting of that snare that shall catch the sun."[391]